This special issue collects articles by colleagues and friends of Wim Ubachs that were submitted on the occasion of his official retirement from the Vrije Universiteit Amsterdam. The topics covered by the special issue span a broad range of scientific activities at the intersection of molecular physics, molecular spectroscopy, atmospheric chemistry, astrophysics, and fundamental physics. These topics were at the heart of Wim’s extraordinary career over the past 40 years, reflected by over 350 publications and numerous scientific breakthroughs. The special issue is a tribute to Wim’s scientific achievements and to the important role he has played and still plays in these fields. It follows a symposium organised in his honour at the Vrije Universiteit at the occasion of his formal and mandatory retirement.
Wim’s scientific career is devoted to precision molecular spectroscopy, with contributions covering all main aspects of this discipline: the development of new instruments, of new spectroscopic methods and their applications to fundamental investigations of molecular structure and dynamics, to atmospheric chemistry and astrophysics, and even to problems related to physics beyond the standard model. Those who have worked closely with Wim were profoundly influenced by his approach to science, and his ability to recognise emerging fields and how to make original contributions in these fields by combining his experience with the experience of those he sought and found as collaborators. Wim’s passion and enthusiasm for molecular spectroscopy in particular, and for science in general, his pragmatic approach to new problems, and his ability to work with others inspired numerous collaborations. Through a rare combination of great personal charm, generosity, persuasion and scientific excellence, he inspired generations of PhD students and postdocs and brought numerous national and international collaborations to a success.
Those who visited Wim and his group in Amsterdam or enjoyed his visits to their own institutions were taken by his personal warmth, and with time could share with him more than just science. Wim and his wife Ghislaine offered their generous hospitality to many scientists who came to Amsterdam. Every year they organised a Christmas get-together for the research group, often including ex-members. Their home – a house on a canal in earlier years and a spacious apartment in the very centre of the city more recently – has been arranged with superb taste by Ghislaine and Wim, with the help of their son Jef. On these occasions their friends could discover more facets of the family life (of the Ubachs): their love for concerts and opera performances, sports activities such as bicycle riding in the Dutch plains around Amsterdam, or hiking in the somewhat steeper Alps during their visits abroad. Social exchanges and discussions with Wim, Ghislaine, Jef, and many of their friends coming from a non-scientific background have always been, and still are, inspiring and enriching.
The introductory part of this special issue includes Wim’s curriculum vitae and lists of his PhD students, postdocs, and main collaborators. It also includes Wim’s full publications list, offering the opportunity of discovering or rediscovering individual items of his incredibly rich and diverse scientific output.
Wim Ubachs received his education from Nijmegen University (now Radboud University), with a Doctorandus degree (equivalent to a Masters degree) in 1982 on a project in solid-state physics carried out at the High-Magnetic-Field Laboratory in Nijmegen. For his PhD-project, which he completed in 1986 under the supervision of Antony Dymanus and Hans ter Meulen, also at Nijmegen, he performed high-resolution spectroscopy of diatomic hydrides (OH, SH, CH, NH) using a narrow-band tunable ultraviolet laser. Immediately after his PhD, he visited the Dalian Institute of Chemical Physics for four months in 1986 as one of the first Dutch physicists visiting China and working in Mainland China, based on a bilateral agreement between the Netherlands Ministry of Science and Education and the Chinese Academy of Sciences. After a postdoctoral fellowship at Stanford University with Richard N. Zare, learning about extreme-ultraviolet (XUV) lasers, he returned to the Netherlands in 1988 to join the Atomic Physics research group led by Wim Hogervorst at the Vrije Universiteit Amsterdam, first as a Lecturer, then a Senior Lecturer, before becoming Full Professor in 2003. In Amsterdam, he started a line of research on broadly tunable, narrowband XUV laser radiation and its application in precision molecular spectroscopy, as one of the first in Europe. This subject remained a central theme throughout his career. Particular highlights were the first laser excitation of helium at 58 nm and the determination of the Lamb shift in the ground state of helium with one of his first PhD students and later colleague Kjeld Eikema, initially using a narrow-band Fourier-transform-limited XUV laser source, and later employing XUV Ramsey spectroscopy using pulses from a frequency-comb laser.
The research program on precision spectroscopy with XUV lasers developed in various directions. The narrow bandwidth XUV radiation sources allowed for detailed measurements of perturbation and predissociation phenomena in the carbon monoxide and nitrogen molecules, in connection to astrophysics and atmospheric physics. This line of research was strengthened when the vacuum-ultraviolet Fourier-transform spectrometer was opened at the DESIRS beamline of the synchrotron ‘Soleil’ in Paris in 2007. Wim and his group became frequent users of this advanced facility, investigating pre-dissociation in electronically excited states of N2 and CO. He also measured the lifetimes of excited states in these molecules by time-domain pump-probe spectroscopy using VUV picosecond lasers during multiple visits and collaborating with scientists from the Lund Laser Centre.
An important focus of his work in XUV laser spectroscopy concerned measurements in molecular hydrogen, starting with a first publication in 1994 and eventually leading to over 100 papers on the subject, with activities still on-going. XUV-laser sources were combined in multiple-laser resonance techniques, demonstrating the excitation of long-lived outer-well states above the ionisation limit, that are resistant to autoionisation. He opened the subject of ‘heavy Rydberg states’, first probing such states in the time domain via coherent spectroscopy, and later also in the frequency domain through a spectroscopic measurement of a Rydberg series in the H+H− system, analogous to a ‘heavy Bohr atom’. The application of double-resonance techniques in the hydrogen molecule also involved measurements of inter-Rydberg transitions in H2 as a possible carrier of the diffuse interstellar bands.
In a separate activity, Wim and his group exploited cavity ring-down (CRD) spectroscopy to determine the absorption cross sections of water vapour in the visible range for the retrieval of the water–vapour column density from satellite data (from the GOME and SCIAMACHY satellites). With this technique, he established the first direct measurement of Rayleigh-scattering cross sections of gases, which had previously always been extracted from refractive indices since Rayleigh’s first derivation. In a collaboration with Harold Linnartz from the Leiden Laboratory of Astrophysics, the CRD setup was combined with a slit-jet plasma-expansion source for the spectroscopic investigation of carbon-chain molecules, with the goal of identifying possible carriers of the Diffuse Interstellar Bands. Several ultraviolet bands of C3 could be detected in a translucent interstellar cloud, a Renner-Teller analysis was performed for C6H in its electronically excited manifold, and the structures of C9H3 and C11H3 were determined from isotopic substitution in the plasma. Wim also applied CRD spectroscopy to the study of collision-induced resonances in the O2–O2 system, of relevance for the analysis of clouds in the atmosphere from satellite data. As a further application of molecular spectroscopy in atmospheric physics, Wim and his group developed a powerful approach for measuring Rayleigh–Brillouin scattering spectral profiles of molecular gases including air, in connection to the ADM-Aeolus satellite mission of the European Space Agency to observe the Earth’s wind profile based on LIDAR. Besides obtaining pressure- and temperature-dependent scattering profiles, this work also led to methods of determining bulk viscosities and thermodynamic properties of gases.
In the past two decades, the main focus of Wim’s work has been on precision spectroscopy of hydrogen molecules for testing fundamental physics theories. Through laboratory laser spectroscopy, the transition frequencies of over 160 lines in the Lyman and Werner bands were measured at a relative frequency accuracy (Δν/ν) of 5 × 10−8. The same lines could be detected in astronomical spectra of absorbing galaxies in the line of sight of distant quasars. Wim and his team, in collaboration with Michael Murphy (Melbourne), performed observations at the ESO Very Large Telescope on various quasars. From a detailed analysis of the 10 best H2/HD high-redshift absorbers and a quantitative comparison of the laboratory with the quasar data, an upper limit for a possible space-time variation of the proton-to-electron mass ratio was derived: this constant of nature varied by less than 5 × 10−6 over the past 10–12 billion years, if at all. The team also put a constraint on a dependence of this constant on gravitational fields by analysing H2 absorption in the photosphere of white dwarf stars in our galaxy using data from the Hubble Space Telescope. In a parallel effort, his team, in particular involving colleague Hendrick Bethlem, had discovered, from calculations, that the methanol molecule is the most sensitive probe to detect a possible variation of the proton-to-electron mass ratio. This finding ignited a program in radio astronomy (collaborating with Karl Menten of the Max Planck Institute at Bonn), using the Effelsberg, IRAM and ALMA radio telescopes detecting methanol, all in one single absorbing galaxy at redshift z = 0.88, which led to a constraint on a varying proton-to-electron mass ratio of less than 10−7 at half the age of the Universe.
The precision measurements of hydrogen molecules in Wim’s team were extended to all six isotopomers H2, HD, D2, HT, DT and T2, with the goal of testing quantum-electrodynamics (QED) calculations in molecules. In particular, the dissociation and ionisation energies of H2, D2 and HD were determined in a collaboration involving Amsterdam, Zurich (group of Frédéric Merkt) and Orsay (Christian Jungen). The results were compared with the results of full theoretical calculations including nonadiabatic, relativistic and QED corrections performed by Krzysztof Pachucki (Warsaw) and his co-workers, finding excellent agreement so far. Wim also demonstrated spectroscopy of the highest vibrational states (up to v = 14) in hydrogen by the innovative method of photodissociation of H2S to test molecular quantum mechanics at large internuclear separations. Besides testing QED calculations in molecules, the extensive range of results on molecular hydrogen also led to constraints on the existence of potential ‘fifth’ forces and higher dimensions in the realm of physics beyond the Standard Model of Particle Physics.
Wim was involved in other spectroscopic studies of molecules for fundamental physics. In Amsterdam, he collaborated with his colleague Jeroen Koelemeij to perform a precision measurement of vibrational transitions in the HD+ ion, which has led to the determination of the value for the proton-to-electron mass ratio at the parts-per-trillion level, currently the most precise determination of this fundamental property of nature. He is also involved in a Netherlands collaboration (NL-eEDM), with scientists from Groningen University, aimed at measuring the electric dipole moment of the electron (eEDM), using the BaF molecule. His recent work in precision metrology of neutral hydrogen is devoted to investigations of ro-vibrational transitions in the ground state. Using a novel approach based on NICE-OHMS (noise-immune cavity-enhanced optical-heterodyne molecular spectroscopy), his group performed saturation spectroscopy on the very weak (2-0) overtone transitions in HD. Very recently, this work was extended to measure a Lamb dip in a quadrupole transition of a molecule, in this case H2, opening a new territory of precision metrology for testing fundamental physics.
Wim’s activity had impact beyond the scientific activities listed above. Based on his unique experience in XUV-laser radiation, Wim played a key role in setting up the LaserLaB in Amsterdam with Wim Hogervorst, which rapidly became a central facility of the Vrije Universiteit, gathering groups workings in areas as diverse as chemistry, biophysics and metrology. He was also strategically and scientifically involved in establishing the Advanced Research Center for NanoLithography (ARCNL) on the Amsterdam Science Campus, which is funded by the company ASML (world market leader in wafer stepper equipment for the production of computer chips), the Dutch Research Council (NWO) and the two Amsterdam universities, the Vrije Universiteit Amsterdam and the University of Amsterdam. In 2014, he set up a ‘second’ group at ARCNL, with Oscar Versolato and Ronnie Hoekstra, devoted to the investigation of laser-produced plasma of tin microdroplets for the generation of Extreme Ultraviolet light (at 13.5 nm) used in the advanced lithography machines of ASML.
The vigour of Wim’s activities at the Vrije Universiteit on hydrogen metrology, and his activities within the NL-eEDM collaboration, and at ARCNL, have not been affected by his official retirement. It is a great joy for all his colleagues and friends to see these activities flourishing.
Wim, on behalf of all your friends and colleagues, we thank you and wish you much success in your numerous post-retirement projects!
Appendix 1: Curriculum Vitae of Wim Ubachs
Affiliations
Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Emeritus professor
Advanced Research Center for NanoLithography, Amsterdam
Research ID: F-5649-2011
URL for web sites: www.few.vu.nl/~wimu and https://arcnl.nl/research-groups/euv-plasma-processes
Email: [email protected]; [email protected]
EDUCATION
1986 1986 PhD, Department of Physics and Astronomy, Radboud University of Nijmegen, Netherlands; Thesis entitled “High-resolution laser spectroscopy of diatomic hydrides”, with advisors Prof. Antony Dymanus and Prof. Hans ter Meulen.
1982 1982 Master of Physics, Department of Physics and Astronomy, Solid State Physics and High-Magnetic Field Laboratory, Radboud University of Nijmegen, Netherlands
PREVIOUS POSITIONS
1986 1986 Visiting Scientist (KNAW scholarship) at the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
1987--1988 1987–1988 PostDoctoral Fellow, Department of Chemistry, Stanford University, USA
1988--2003 1988–2003 Lecturer and Senior Lecturer at Department of Physics, Vrije Universiteit Amsterdam
2001--2004 2001–2004 Endowed Professor, Technical University Eindhoven, The Netherlands
2003-- 2003– Full Professor of Atomic, Molecular and Laser Physics, Vrije Universiteit Amsterdam
INSTITUTIONAL RESPONSIBILITIES
2000–2010 Director of Laser Centre Vrije Universiteit Amsterdam
2010–2014 Head of Department of Physics, Vrije Universiteit Amsterdam
FELLOWSHIPS AND AWARDS
2002 Guest Professorship, ETH Zürich, Switzerland
2006 Guest Professorship at the Tokyo University of Science
2012 Prize, Templeton Foundation, New Frontiers in Astronomy and Cosmology
2015 ERC Advanced grant
2017 Appointed Fellow of the American Physical Society
COMMISSIONS OF TRUST
2010–2014 Scientific Advisory Board, FOM Institute AMOLF, Amsterdam
2008–2012 Scientific Advisory Board, National Laser Centre of South Africa, Pretoria
2012– Review panel member, German Excellence Initiative for University Research (various)
2007– Editorial Board Molecular Physics
Editorial Board: Journal of Molecular Spectroscopy
2003–2013 International Scientific Committees: HRMS Dijon; ICOLS
2005–2011 Board of “Stichting Physica”, Dutch funding organization supporting outreach activities
2005–2009 Board of EPS-AMO Division
2003–2010 Member of Participants Council of LaserLaB-Europe
2009–2011 Member of the Strategic and Technical Advisory Committee of the VIRGO gravitational wave detector
2021– Scientific Advisory Committee, HFML-FELIX infrastructure at Radboud University Nijmegen
MEMBERSHIPS OF SCIENTIFIC SOCIETIES
>25 years Member of Netherlands Physical Society (NNV), European Physical Society (EPS) and
American Physical Society (APS)
REFEREEING
Ubachs has been a regular referee for a large number of journals, most notably Phys. Rev. Lett., Phys. Rev. A, J. Phys. B, Optics Letters, Optics Express, Science. In addition, he was referee panel member for DPG (Germany) and Alexander von Humboldt Foundation (Germany), NSF (USA), EPSRC (UK), as well as Australian, South-African, French, Swiss, and Canadian national funding agencies.
Highlights and awards for refereeing:
- Outstanding reviewer for the Journal of Molecular Spectroscopy
- Outstanding reviewer for the Journal of Quantitative Spectroscopy and Radiative Transfer
- Top reviewer for The Journal of Chemical Physics (2015)
SCIENTIFIC COLLABORATIONS
Wim Ubachs has collaborated with many scientists from all over the world:
The team of Quantum Metrology and Laser Applications (formerly Atomic Physics) at LaserLab VU Amsterdam: Wim Hogervorst, Kjeld Eikema, Wim Vassen, Edcel Salumbides, Hendrick Bethlem, Jeroen Koelemeij, Max Beyer and Laura Dreissen;
The colleagues at ARCNL: Oscar Versolato and Ronnie Hoekstra from the EUV Plasma Physics Processes and EUV Source group, Stefan Witte from the EUV Generation and Imaging group, and John Sheil from the Plasma Theory and Modelling group;
The eEDM-NL team: Steven Hoekstra, Hendrick Bethlem, Anastasia Borschevsky, Klaus Jungmann, Rob Timmermans, Lorenz Willmann, Groningen (Netherlands) – Measurement of the electric dipole moment of the electron;
Frédéric Merkt, ETH Zürich (Switzerland) – Precision spectroscopy of molecular hydrogen;
Krzysztof Pachucki, University of Warsaw, and Jacek Komasa and Mariusz Puchalski, University of Poznan (Poland) – QED tests of hydrogen molecules;
Harold Linnartz, Leiden University (Netherlands) and DongFeng Zhao, USTC Hefei (China) – Cavity-ring-down spectroscopy and laboratory astrophysics;
Michael Murphy, Swinburne University, and John Webb, UNSW Sydney (Australia) – Astronomical observation, quasar absorption spectra and varying constants;
Christian Jungen, Laboratoire Aimé Cotton, Orsay (France) – Excited states of molecular hydrogen;
Lutoslaw Wolniewicz – Double well states in hydrogen;
Shuiming Hu and Cunfeng Cheng, USTC Hefei (China) – Precision spectroscopy of molecular hydrogen;
Karl Menten and Christian Henkel, Max Planck Institut für Radioastronomie Bonn (Germany), Dr. Sebastien Muller, Onsala Space Observatory (Sweden), Nissim Kanekar, Tata Institute, Pune (India) and Sergei Levshakov, Ioffe Institute, St. Petersburg (Russia) – Radio astronomy for varying constants;
Nelson de Oliveira and Laurent Nahon, Synchrotron Soleil Paris (France) – synchrotron FT-VUV studies of molecules;
Isabelle Kleiner, LISA and Université Diderot Paris (France) – Polyatomic molecules and varying constants;
Anne L’Huillier and Claes-Göran Wahlström, Lund Laser Centre (Sweden) – Lifetime studies in CO and nitrogen molecules with picosecond VUV-lasers;
Patrice Cacciani, Université de Lille (France) – Predissociation in carbon monoxide;
Rafal Hakalla, University Rzeszow (Poland) and Bob Field, MIT (USA) – Spectroscopy of carbon monoxide;
Peter Sorokin and Jim Glownia, IBM New York – Diffuse Interstellar bands
Brenton Lewis and Ken Baldwin, ANU Canberra (Australia) – Predissociation studies of nitrogen;
Lydia Tchang-Brillet and Evelyne Roueff, Observatoire de Paris, Meudon (France) – VUV spectroscopy of molecules, and theory of varying constants in hydrogen molecules;
Alan Heays and Ewine van Dishoeck, Leiden University (Netherlands) – Astrochemistry studies;
Steven Stolte and Kees de Lange, VU Amsterdam (Netherlands) – Molecular photoionisation and photodissociation studies;
Attila G. Császár and Roland Tobias, Budapest (Hungary), and Cristina Puzzarini (Bologna) – Saturation spectroscopy of water;
Kun Liang, Huazhong University, Wuhan (China), Benjamin Witschas, DLR Oberpfaffenhofen (Germany), Willem van de Water, TU Delft (Netherlands), and Wilson Marques Jr, Curitiba (Brasil) – Rayleigh-Brillouin scattering in gases;
Magnus Schlösser, Karlsruhe Institute of Technology (Germany) – Spectroscopy of tritiated hydrogen molecules;
Jean-Philippe Karr and Laurent Hilico, Laboratoire Kastler Brossel, ENS, Paris (France) and Vladimir Korobov, Bogoliubov Laboratory, Dubna (Russia) – Spectroscopy of HD+;
Taco Visser, VU Amsterdam and Institute of Optics, Rochester (USA) – Plasmonics;
José Crespo, Max Planck Institute for Nuclear Physics, Heidelberg (Germany) – EBIT spectroscopy of Sn ions.
Bert Schellekens and Beatriz Gato-Rivera (Nikhef, Amsterdam) – Extra dimensions
PhD STUDENTS OF WIM UBACHS
Wim Ubachs supervised a large number of PhD students and acted as Promotor or Co-Promotor at their Thesis defence. Below a full list of PhD students is given with name, country of origin, Thesis title and date of defence:
Kin Fung Lai (HongKong)
Laser precision spectroscopy on hydrogen isotopologues:
Tritiated molecules and vibrationally excited H2
Defense: 28 June 2022
Joel Hussels (Netherlands)
Improved determination of the dissociation energy of H2, HD, and D2
Defense: 6 Dec 2021
Ruben Schupp (Germany)
Spectral characterization of solid-state laser-driven plasma sources of EUV light
Defense: 17 Mar 2021
Ruud van der Beek (Netherlands)
Bloch oscillations of meta-stable helium in an optical lattice
Defense: 17 Mar 2021
Joris Scheers (Netherlands)
Charge-state-resolved spectroscopy of multiply-charged tin ions
Defense: 10 Nov 2020
Xia Zhang (China)
Theoretical study of rotationally inelastic scattering of molecules
Defense: 5 March 2020
Francesco Torretti (Italy)
Spectroscopy of highly-charged Sn ions for extreme ultraviolet nanolithography
Defense: 19 December 2019
Yuanqing Wang (China)
Spontaneous Rayleigh-Brillouin Scattering in Molecular Gases
Defense: 4 December 2019
Xavier Bacalla (Philippines)
Electronic Spectroscopy of Molecules of Astrophysical Interest;
Towards improving our knowledge of the DIB carriers
Defense: 2 July 2019 (Leiden)
Mart-Johan Deuzeman (Netherlands)
Generation and interaction of energetic tin ions
Defense: 21 June 2019 (Groningen)
Sayan Patra (India)
Towards Doppler-free two-photon spectroscopy of trapped and cooled HD+ ions
Defense: 9 May 2019
Dmitry Kurilovich (Belarus)
Laser-induced dynamics of liquid tin microdroplets
Defense: 4 April 2019
Madhu Talluri Trivikram (India)
High-Precision REMPI and CARS studies on molecular hydrogen and tritium
Defense: 7 February 2019
Bob Rengelink (Netherlands)
A magic wavelength optical dipole trap for high-precision spectroscopy of ultracold metastable helium
Defense: 10 December 2018
Robert Altman (Netherlands)
Ramsey-comb spectroscopy in the deep ultraviolet for tests of molecular quantum theory
Defense: 13 November 2018
Aernout van der Poel (Netherlands)
Cold Collisions in a Molecular Synchrotron
Defense: 13 March 2018
Mario Dapra (Italy)
Search for drifting constants of nature via optical and radio astronomy
Defense: 20 November 2017
Adonis Silva Flores (Philippines)
An ultracold, optically trapped mixture of 87Rb and metastable 4He atoms
Defense: 30 May 2017
Remy Notermans (Netherlands)
High-Precision spectroscopy of Forbidden Transitions in Ultracold 4He and 3He
Defense: 15 March 2017
Jurriaan Biesheuvel (Netherlands)
Probing QED and fundamental constants through vibrational spectroscopy of HD+
Defense: 28 June 2016
Mingli Niu (China)
High Resolution Laser and Synchrotron Spectroscopic Studies on H2 and CO
Defense: 30 November 2015
Mohammad Rafiee Fanood (Iran)
Molecular chirality under the reaction microscope:
Mass-selective photoelectron circular dichroism of pure and multi-component enantiomeric mixtures
Defense: 22 October 2015
Congsen Meng (China)
Femtosecond laser detection of xenon and Stark decelerated polyatomic molecules
Defense: 30 June 2015
Julija Bagdonaite (Lithuania)
Search for a variation of the proton-electron mass ratio from molecular hydrogen and methanol
Defense: 7 April 2015
Ziyu Gu (China)
Spontaneous Rayleigh-Brillouin Scattering on Atmospheric Gases
Defense: 23 March 2015
Adrian J. de Nijs (Netherlands)
Molecular radicals in the search for drifting constants
Defense: 2 October 2014
Marina Quintero Perez (Spain)
Preparation of an ultra-cold sample of ammonia molecules for precision measurements
Defense: 8 September 2014
Mohammad Ali Haddad (Iran)
Cavity Ring-Down Laser Spectroscopy of Carbon-Chain Molecules
Defense: 24 March 2014
Paul Jansen (Netherlands)
Polyatomic molecules for probing a possible variation of the proton-to-electron mass ratio
Defense: 1 July 2013
Gareth Dickenson (South Africa)
Laser and Synchrotron Spectroscopic Studies of Molecular Hydrogen
Defense: 8 May 2013
Shreyas Raghunathan (India)
Studies in Physical optics; Coherence Theory and Surface Plasmons
Defense: 3 May 2013 (TU Delft)
Rob van Rooij (Netherlands)
Frequency Metrology in Quantum Degenerate Helium
Defense: 8 June 2012
Dominik Kandula (Poland)
XUV Frequency Comb Metrology and the Ground State of Helium
Defense: 1 December 2011
Anne Lisa Wolf (Netherlands)
Frequency comb spectroscopy on trapped calcium ions
Defense: 7 July 2011
Thomas van Dijk (Netherlands)
Experimental and Theoretical studies in Optical Coherence Theory
Defense: 4 April 2011
Maria Ofelia Vieitez Hornos (Uruguay)
XUV laser studies of Rydberg-valence states in N2 and H + H- heavy Rydberg states
Defense: 2 June 2010
Toncho Ivanov (Bulgaria)
XUV spectroscopy of highly excited states in H2, HD and D2
Defense: 7 December 2010
Dmitry Ityaksov (Russia)
Cavity Ring-Down Optical Extinction Measurements of Atmospheric Molecules
Defense: 30 November 2009
Edcel John Salumbides (Philippines)
Laser metrology studies for probing variation of fundamental constants
Defense: 26 May 2009
Lineke van der Sneppen (Netherlands)
Liquid-phase cavity ring-down spectroscopy for improved analytical detection sensitivity
Defense: 10 November 2008
Sandro Hannemann (Germany)
Deep-ultraviolet frequency metrology with a narrowband titanium: sapphire laser
Defense: 24 May 2007
Arjan Sprengers (Netherlands)
Extreme ultraviolet laser excitation of molecular nitrogen; perturbations and predissociation
Defense: 29 June 2006
Marc Smits (Netherlands)
Multi active electron effects in the strong field ionization of transition metal atoms and clusters
Defense: 22 February 2005
Maarten Sneep (Netherlands)
The atmosphere in the laboratory: cavity ring-down measurements on scattering and absorption
Defense: 23 November 2004
Fernando Brandi (Italy)
Table-top tunable narrow-band extreme ultraviolet sources: from low to high-order optical harmonic generation
Defense: 1 July 2004
Ruediger Lang (Germany)
Spectral Sampling Techniques for Atmospheric modeling
Defense: 31 October 2002
Arno de Lange (Netherlands)
XUV Multi-resonance spectroscopy of hydrogen and nitrogen
Defense: 14 February 2002
Iavor Velchev (Bulgaria)
Stimulated Brillouin Scattering Pulse Compression and Harmonic Generation
Defense: 7 June 2001
Hans Naus (Netherlands)
Cavity Ring-Down Spectroscopy on Atmospheric Molecules
Defense: 13 February 2001
Elmar Reinhold (Germany)
Extreme Ultraviolet Laser Spectroscopy of the hydrogen molecule: excited states with large internuclear separation
Defense: 18 May 2000
Paul Hinnen (Netherlands)
XUV-laser spectroscopy of H2 and the mystery of the diffuse interstellar bands
Defense: 15 September 1997
Kjeld Eikema (Netherlands)
QED and the ground state of helium; precision extreme ultraviolet laser spectroscopy
Defense: 24 June 1996
Robert van Leeuwen (Netherlands)
Electron correlation in autoionizing states of barium
Defense: 11 December 1995
Pieternel Levelt (Netherlands)
A coherent XUV-source for high resolution spectroscopy: application to diatomic molecules
Defense: 11 November 1992
Ilse Aben (Netherlands)
Resonance CARS in I2 and Br2
Defense: 29 September 1992
Robert de Graaf (Netherlands)
Dielectronic states in barium
Defense: 17 October 1991
PhD students currently working with Wim Ubachs as (Co)-Supervisor:
Frank Cozijn (Netherlands), Meissa Diouf (Senegal), Lars Behnke (Germany)
Zoi Bouza (Greece), Charlaine Roth (Switzerland), Maarten Mooij (Netherlands)
Elmer Gründeman (Netherlands), Wander van der Meer (Netherlands)
Yahia Mostafa (Egypt)
Post-Docs having worked with Wim Ubachs:
Stephan Schiemann, Wojtek Majewski, Dragomir Neshev, Urs Hollenstein, Josselin Philip, Eric-Jan van Duijn,
Alan Heays, DongFeng Zhao, CunFeng Cheng, Chris Medcraft, Matthias Germann
Appendix 2: Publication list of Wim Ubachs
[387] F.M.J. Cozijn, M.L. Diouf, W. Ubachs,
Lamb dip of a quadrupole transition in H2
arXiv: 2303.17818 (2023).
[386] A. Boeschoten, V.R. Marshall, T.B. Meijknecht, A. Touwen, H.L. Bethlem, A. Borschevsky, S. Hoekstra, J.W.F. van Hofslot, K. Jungmann, M.C. Mooij, R.G.E. Timmermans, W. Ubachs, L. Willmann,
Novel spin-precession method for sensitive EDM searches
arXiv: 2303.06402 (2003).
[385] K.-F. Lai, M. Beyer, W. Ubachs,
Spectroscopic study of the F1Σg+ outer well state in H2, HD and D2
J. Mol. Spectr. 393, 111778 (2023).
[384] M.L. Diouf, R. Tobias, F.M.J. Cozijn, E.J. Salumbides, C. Fabri, C. Puzzarini, A.G. Csaszar, W. Ubachs,
Parity-pair-mixing effects in nonlinear spectroscopy of HDO
Opt. Express 30, 46040-46059 (2022).
[383] F.M.J. Cozijn, M.L. Diouf, W. Ubachs,
Saturation spectroscopy of R(0), R(2) and P(2) lines in the (2-0) band of HD
Eur. J. Phys. D 76, 220 (2022).
[382] K. Liang, J. Xu, Y. Wang, H.-F. Lu, W. Ubachs,
Grüneisen approach for universal scaling of the Brillouin shift in gases
New. J. Phys. 24, 103005 (2022).
[381] M.L. Diouf, R. Tobias, T.S. van der Schaaf, F.M.J. Cozijn, E.J. Salumbides, A.G. Csaszar, W. Ubachs,
Ultraprecise relative energies in the (2, 0, 0) vibrational band of H216O
Mol. Phys. 120, e2050430 (2022).
[380] K.-F. Lai, E.J. Salumbides, M. Beyer, W. Ubachs,
Precision measurement of quasi-bound resonances in H2 and the H + H scattering length
Mol. Phys. 120, e2018063 (2022).
[379] M.L. Diouf, F.M.J. Cozijn, V. Hermann, E.J. Salumbides, M. Schloesser, W. Ubachs,
Rotational level spacings in HD from vibrational saturation spectroscopy
Phys. Rev. A 105, 062823 (2022).
[378] K.-F. Lai, D. Manalili, W. Ubachs, R. Cooke, M. Pettini, N. de Oliveira, E.J. Salumbides,
Vacuum UV Fourier-transform spectroscopy of 16O and 18O
Astroph. J. Suppl. Series 260, 37 (2022).
[377] M. Denis, P.A.B. Haase, M.C. Mooij, Y. Cha morro, P. Aggarwal, H.L. Bethlem, A. Boeschoten, A. Borschevsky, K. Esajas, Y. Hao, S. Hoekstra, J.W.F. van Hofslot, V.R. Marshall, T.B. Meijknecht, R.G.E. Timmermans, A. Touwen, W. Ubachs, L. Willmann, Y. Yin,
Benchmarking of the Fock space coupled cluster method and uncertainty estimation: Magnetic hyperfine interaction in the excited state of BaF
Phys. Rev. A 105, 052811 (2022).
[376] S. Ryzner, M. I. Malicka, A.N. Heays, R.W. Field, N. de Oliveira, W. Szajna, W. Ubachs, R. Hakalla,
VUV-VIS FT spectroscopy of the 13C18O less abundant isotopologue of carbon monoxide: Analysis of the A1Π(v = 1) multiply-perturbed level
Spectrochim. Acta A 279, 121367 (2022).
[375] O.O. Versolato, J. Sheil, S.M. Witte, W. Ubachs, R. Hoekstra,
Microdroplet-tin plasma sources of EUV radiation driven by solid-state-lasers
J. of Optics 24, 054014 (2022).
[374] J. Hussels, N. Hoelsch, C.-F. Cheng, E. J. Salumbides, H. L. Bethlem, K. S. E. Eikema, Ch. Jungen, M. Beyer, F. Merkt, W. Ubachs,
Improved ionization and dissociation energies of the deuterium molecule
Phys. Rev. A 105, 022820 (2022).
[373] L. Poirier, A. Bayerle, A. Lassise, F. Torretti, R. Schupp, L. Behnke, Y. Mostafa, W. Ubachs, O. Versolato, R. Hoekstra,
Absolute cross-calibration of a combined electrostatic and time-of-flight analyzer for energy- and charge-state-resolved spectrometry of tin laser-pro duced plasma
Appl. Phys. B 128, 39 (2022).
[372] K.-F. Lai, E.J. Salumbides, W. Ubachs, M. Beyer,
Shape resonances in H2 as photolysis reaction intermediates
Phys. Rev. Lett. 127, 183001 (2021).
[371] Z. Bouza, J. Byers, J. Scheers, R. Schupp, Y. Mostafa, L. Behnke, Z. Mazzotta, J. Sheil, W. Ubachs, R. Hoekstra, M. Bayraktar, O.O. Versolato,
The spectrum of a 1-mum-wavelength-driven tin microdroplet laser-produced plasma source in the 5.5-265.5 nm wavelength range
AIP Advances 11, 125003 (2021).
[370] P. Aggarwal, Y. Yin, K. Esajas, H.L. Bethlem, A. Boeschoten, A. Borschevsky, S. Hoekstra, K. Jungmann, V.R. Marshall, T.B. Meijknecht, M.C. Mooij, R.G.E. Timmermans, A. Touwen, W. Ubachs, L. Willmann,
Deceleration and trapping of SrF molecules
Phys. Rev. Lett. 127, 173201 (2021).
[369] D. Hemminga, L. Poirier, M.M. Basko, R. Hoekstra, W. Ubachs, O.O. Versolato, J. Sheil,
High-energy ions from Nd:YAG laser ablation of tin microdroplets: Comparison between experiment and a single-fluid hydrodynamic model
Plasma Sources Science Techn. 30, 105006 (2021).
[368] M. Melosso, M.L. Diouf, L. Bizzocchi, M. Harding, F.M.J. Cozijn, C. Puzzarini, W. Ubachs,
Hyperfine-Resolved Near-Infrared Spectra of H217O
J. Phys. Chem. A 125, 7884-7890 (2021).
[367] M. I. Malicka, S. Ryzner, A.N. Heays, N. de Oliveira, R.W. Field, W. Ubachs, R. Hakalla,
Deperturbation analysis of the A1Π(v = 2) level in the 12C18O isotopologue
J. Quant. Spectr. Rad. Transfer 273, 107837 (2021).
[366] P.A.B. Haase, D.J. Doeglas, A. Boeschoten, E. Eliav, M. Ilias, P. Aggarwal, H.L. Bethlem, A. Borschevsky, K. Esajas, Y. Hao, S. Hoekstra, V.R. Marshall, Th. Meijknecht, M. Mooij, K. Steinebach, R.G.E. Timmermans, A. Touwen, W. Ubachs, L. Willmann, Y. Yin
Systematic study and uncertainty evaluation of P,T-odd relativistic enhancement factors in BaF
J. Chem. Phys. 155, 034309 (2021).
[365] M. Germann, S. Patra, J.-Ph. Karr, L. Hilico, V. I. Korobov, E. J. Salumbides, K. S. E. Eikema, W. Ubachs, and J. C. J. Koelemeij,
Three-body QED test and fifth-force constraint from vibrations and rotations of HD+
Phys. Rev. Res. 3, L022028 (2021).
[364] R. Schupp, L. Behnke, Z. Bouza, Z. Mazzotta, Y. Mostafa, A. Lassise, L. Poirier, M. Bayraktar, J. Sheil, W. Ubachs, R. Hoekstra, O.O. Versolato,
Characterization of angularly resolved EUV emission from 2-µm-wavelength laser-driven Sn plasmas using preformed liquid disk targets
J. Phys. D: Applied Physics 54, 365103 (2021).
[363] S. Muller, W. Ubachs, K.M. Menten, C. Henkel, N. Kanekar,
A study of submillimeter methanol absorption toward PKS1830; Excitation, invariance of the proton-electron mass ratio, and systematics
Astron. Astroph. 652, A5 (2021).
[362] M.L. Diouf, R. Tobias, I. Simko, F.M.J. Cozijn, E.J. Salumbides, W. Ubachs, A. Csaszar,
Network-based design of near-infrared Lamb-dip experiments and determination of pure rotational energies of H218O at kHz accuracy
J. Phys. Chem. Ref. Data 50, 023106 (2021).
[361] R. Schupp, L. Behnke, J. Sheil, Z. Bouza, W. Ubachs, R. Hoekstra, O.O. Versolato,
Characterization of 1- and 2-µm-wavelength laser-produced microdroplet-tin plasma for generating extreme-ultraviolet light
Phys. Rev. Res. 3, 013294 (2021).
[360] P. Aggarwal, H.L. Bethlem, A. Boeschoten, A. Borschevsky, K. Esajas, Y. Hao, S. Hoekstra, K. Jungmann, V.R. Marshall, T.B. Meijknecht, M.C. Mooij, R.G.E. Timmermans, A. Touwen, W. Ubachs, S.M. Vermeulen, L. Willmann, Y. Yin, A. Zapara,
A supersonic laser ablation beam source with narrow velocity spreads
Rev. Scient. Instrum. 92, 033202 (2021).
[359] K.-F. Lai, M. Beyer, E.J.Salumbides, W. Ubachs,
Photolysis production and spectroscopic investigation of the highest vibrational states in H2 (X1Σg+ v=13,14)
J. Phys. Chem. A 125, 1221-1228 (2021).
[358] L. Behnke, R. Schupp, Z. Bouza, M. Bayraktar, Z. Mazzotta, R. Meijer, J. Sheil, S. Witte, W. Ubachs, R. Hoekstra, O. Versolato ,
Extreme ultraviolet light from a tin plasma driven by a 2-micron-wavelength laser
Opt. Express 29, 4475-4487 (2021).
[357] Y. Wang, Z. Gu, K. Liang, W. Ubachs,
Rayleigh-Brillouin light scattering spectroscopy of air; experiment, predictive model and dimensionsless scaling
Mol. Phys. 119, e1804635 (2021).
[356] Y. Wang, W. Ubachs, C.A.M. de Moraes, W. Marques Jr,
Rayleigh-Brillouin scattering in binary mixtures of disparate-mass constituents: SF6-He, SF6-D2 and SF6-H2
Phys. Rev. E 103, 013102 (2021).
[355] W. Ubachs,
Crisis and Catharsis in atomic physics
Science 370, 6520 (2020).
[354] J. Hussels, C. Cheng, E.J. Salumbides, W. Ubachs,
Chirp-compensated pulsed Titanium-Sapphire laser system for precision spectroscopy
Opt. Letters 45, 5909 (2020).
[353] Sayan Patra, M. Germann, J.-Ph. Karr, M. Haidar, L. Hilico, V.I. Korobov, F.M.J. Cozijn, K.S.E. Eikema, W. Ubachs, J.C.J. Koelemeij,
Proton-electron mass ratio from laser spectroscopy of HD+ at the part-per-trillion level
Science 369, 1238-1241 (2020).
[352] K.F. Lai, W. Ubachs, N. de Oliveira, E.J. Salumbides,
Fourier-transform VUV spectroscopy of 14,15N and 12,13C
Atoms 8, 62 (2020).
[351] L. Wu, Q. Li, H. Liu, W. Ubachs,
Extraction of the translational Eucken factor from light scattering by molecular gas
J. Fluid. Mechanics 901, A23 (2020).
[350] M. I. Malicka, S. Ryzner, A.N. Heays, N. de Oliveira, R.W. Field, W. Ubachs, R. Hakalla,
High-resolution Fourier-transform spectroscopy and deperturbation analysis of the A1Π (v = 1) level in 12C18O
J. Quant. Spectr. Rad. Transfer 255, 107243 (2020).
[349] Z. Bouza, J. Scheers, A. Ryabtsev, R. Schupp, L. Behnke, C. Shah, J. Sheil, M. Bayraktar, J.R. Crespo Lopez-Urrutia, W. Ubachs, R. Hoekstra, O.O. Versolato,
EUV spectroscopy of Sn5+ - Sn10+ ions in an electron beam ion trap and laser-produced plasmas
J. Phys. B 53, 195001 (2020).
[348] J. Scheers, R. Schupp, R. Meijer, W. Ubachs, R. Hoekstra, O. O. Versolato,
Time- and space-resolved optical Stark spectro scopy in the afterglow of laser-produced tin-droplet plasma
Phys. Rev. E 102, 013204 (2020).
[347] K.F. Lai, E.J. Salumbides, W. Ubachs,
Two-photon Doppler-free ultraviolet laser spectroscopy on sulphur atoms
J. Phys. B 53, 175002 (2020).
[346] O. Versolato, A. Bayerle, M. Bayraktar, L. Behnke, H. Bekker, Z. Bouza, J. Colgan, J.R. Crespo Lopez-Urrutia, M.J. Deuzeman, R. Hoekstra, D. Kurilovich, B. Liu, R. Meijer, A. Neukirch, L. Poirier, S. Rai, A. Ryabtsev, J. Scheers, R. Schupp, J. Sheil, F. Torretti, W. Ubachs, S. Witte,
Spectroscopic investigations of YAG-laser-driven microdroplet-tin plasma sources of extreme ultraviolet radiation for nanolithography
J. Phys. Conf. Series 1412, 192006 (2020).
[345] J. Scheers, C. Shah, A. Ryabtsev, H. Bekker, F. Torretti, J. Sheil, D. A. Czapski, J. Berengut, W. Ubachs, J. R. Crespo Lopez-Urrutia, R. Hoekstra, O. O. Versolato,
EUV spectroscopy of highly-charged Sn13+ - Sn15+ ions in an electron beam ion trap
Phys. Rev. A 101, 062511 (2020).
[344] M.L. Diouf, F.M.J. Cozijn, K.F. Lai, E.J. Salum bides, W. Ubachs,
Lamb-peak spectrum of the HD (2-0) P(1) line
Phys. Rev. Res 2, 023209 (2020).
[343] F. Torretti, J. Sheil, R. Schupp, M.M. Basko, M. Bayraktar, R.A. Meijer, S. Witte, W. Ubachs, R. Hoekstra, O.O. Versolato, A.J. Neukirch, J. Colgan,
Prominent radiative contributions from multiply-excited states in laser-produced tin plasma for nanolithography
Nature Comm. 11, 2334 (2020).
[342] K.F. Lai, V. Hermann, T.M. Trivikram, M.L. Diouf, M. Schloesser, W. Ubachs, E.J. Salumbides,
Precision measurement of the fundamental vibrational frequencies of tritium-bearing hydrogen mole cules: T2, DT, HT
Phys. Chem. Chem. Phys. 22, 8973-8987 (2020).
[341] R. Tobias, T. Furtenbacher, I. Simko, A.G. Csaszar, M.L. Diouf, F.M.J. Cozijn, J.M.A. Staa, E.J. Salumbides, W. Ubachs,
Spectroscopic-network-assisted precision spectroscopy and its application to water
Nature Comm. 11, 1708 (2020).
[340] F. Torretti, F. Liu, M. Bayraktar, J. Scheers, Z. Bouza, W. Ubachs, R. Hoekstra, O.O. Versolato,
Spectral characterization of an industrial EUV light source for nanolithography
J. Phys. D: Appl. Phys. 53, 055204 (2020).
[339] J. Xu, B. Witschas, K. Liang, Y. Wang, W. Ubachs,
Characterization of a novel temperature LIDAR receiver by means of laboratory Rayleigh-Brillouin scattering measurements
Eur. Phys. J. Web Conf. 237, 07004 (2020).
[338] A.N. Heays, B.R. Lewis, N. de Oliveira, W. Ubachs,
The spin-forbidden vacuum-ultraviolet absorption spectrum of 14N15N
J. Chem. Phys. 151, 224305 (2019).
[337] K.-F. Lai, P. Czachorowski, M. Schloesser, M. Puchalski, J. Komasa, K. Pachucki, W. Ubachs, E. J. Salumbides,
Precision tests of nonadiabatic perturbation theory with measurements on the DT molecule
Phys. Rev. Res. 1, 033124 (2019).
[336] P. Aggarwal, V.R. Marshall, H.L. Bethlem, A. Boeschoten, A. Borschevsky, M. Denis, K. Esajas, Y. Hao, S. Hoekstra, K. Jungmann, T.B. Meijknecht, M.C. Mooij, R.G.E. Timmermans, A. Touwen, W. Ubachs, S.M. Vermeulen, L. Willmann, Y. Yin, A. Zapara,
Lifetime Measurements of the A2Π1/2 and A2Π3/2 States in BaF
Phys. Rev. A 100, 052503 (2019).
[335] M. Beyer, N. Holsch, J. Hussels, C.-F. Cheng, E.J. Salumbides, K.S.E. Eikema, W. Ubachs, C. Jungen, F. Merkt,
Determination of the interval between the ground states of para- and ortho-H2
Phys. Rev. Lett. 123, 163002 (2019).
[334] M.L. Diouf, F.M.J. Cozijn, B. Darquie, E.J. Salumbides, W. Ubachs,
Lamb-dips and Lamb-peaks in the saturation spectrum of HD
Opt. Lett. 44, 4733 (2019).
[333] R. Schupp, F. Torretti, R. Meijer, M. Baryaktar, J. Sheil, J. Scheers, D. Kurilovich, A. Bayerle, A. Schafgans, M. Purvis, K.S.E. Eikema, S. Witte, W. Ubachs, R. Hoekstra, O.O. Versolato,
Radiation transport and scaling of optical depth in Nd:YAG laser-produced microdroplet-tin plasma
Appl. Phys. Lett. 115, 124101 (2019).
[332] S.H. Jamali, M. de Groen, O.A. Moultos, R. Hartkamp, Th.J.H. Vlugt, W. Ubachs, W. van de Water,
Rayleigh-Brillouin light scattering spectra of CO2 from molecular dynamics
J. Chem. Phys. 151, 064201 (2019).
[331] Y. Hao, L.F. Pasteka, L. Visscher, and the NL-eEDM collaboration: P. Aggarwal, H.L. Bethlem, A. Boeschoten, A. Borschevsky, M. Denis, K. Esajas, S. Hoekstra, K. Jungmann, V.R. Marshall, Th.B. Meijknecht, M.C. Mooij, R.G.E. Timmermans, A. Touwen, W. Ubachs, L. Willmann, Y. Yin, A. Zapara,
High accuracy theoretical investigations of CaF, SrF, and BaF and implications for laser-cooling
J. Chem. Phys. 151, 034302 (2019).
[330] R. Schupp, F. Torretti, R. Meijer, M. Bayraktar, J. Scheers, D. Kurilovich, A. Bayerle, K.S.E. Eikema, S. Witte, W. Ubachs, R. Hoekstra, O.O. Versolato,
Efficient generation of extreme ultraviolet light from Nd:YAG-driven microdroplet-tin plasma
Phys. Rev. Appl. 12, 014010 (2019).
[329] C. Medcraft, H. Linnartz, W. Ubachs,
Cavity Ring-down UV spectroscopy of the C2Σ+-X2Π electronic transition of CH
J. Mol. Spectr. 360, 15-23 (2019).
[328] Y. Wang, W. Ubachs, W. van de Water,
Bulk viscosity of CO2 from Rayleigh-Brillouin light scattering spectroscopy at 532 nm
J. Chem. Phys. 150, 154502 (2019).
[327] M.T. Trivikram, E.J. Salumbides, C. Jungen, W. Ubachs,
Excitation of H2 at large internuclear separation: F1Σg+ outer well states and continuum resonances
Mol. Phys. 117, 2961-2971 (2019).
[326] N. Hoelsch, M. Beyer, E.J. Salumbides, K.S.E. Eikema, W. Ubachs, C. Jungen, F. Merkt,
Benchmarking theory with an improved measurement of the ionization and dissociation energies of H2
Phys. Rev. Lett. 122, 103002 (2019).
[325] W. Ubachs, E.J. Salumbides, M.T. Murphy, H. Abgrall, E. Roueff,
H2/HD molecular data for analysis of quasar spectra in search of varying constants
Astron. Astroph. 622, A127 (2019).
[324] R. Hakalla, T.M. Trivikram, A.N. Heays, E.J. Salumbides, N. de Oliveira, R.W. Field, W. Ubachs,
Precision spectroscopy and comprehensive analysis of perturbations in the A1Π(v = 0) state of 13C18O
Mol. Phys. 117, 79-96 (2019).
[323] L.S. Dreissen, H.F. Schouten, W. Ubachs, S.B. Raghunathan, T.D. Visser,
Active two-dimensional steering of radiation from a nano-aperture
Nano Letters 18, 7207-7210 (2018).
[322] J. Scheers, R. Ryabtsev, A. Borschevsky, J.C. Berengut, K. Haris, R. Schupp, D. Kurilovich, F. Torretti, A. Bayerle, E. Eliav, W. Ubachs, O.O. Versolato, R. Hoekstra,
Energy level structure of Sn3+ ions
Phys. Rev. A98, 062503 (2018).
[321] P. Aggarwal, H.L. Bethlem, A. Borschevsky, M. Denis, K. Esajas, P.A.B. Haase, Y. Hao, S. Hoekstra, K. Jungmann, T.B. Meijknecht, M.C. Mooij, R.G.E. Timmermans, W. Ubachs, L. Willmann, A. Zapara,
Measuring the electric dipole moment of the electron in BaF
Eur. J. Phys. D 72, 197 (2018).
[320] D. Kurilovich, T. de Faria Pinto, F. Torretti, R. Schupp, J. Scheers, A.S. Stodolna, H. Gelderblom, K.S.E. Eikema, S. Witte, W. Ubachs, R. Hoekstra, O.O. Versolato,
Expansion dynamics after laser-induced cavitation in liquid tin microdroplets
Phys. Rev. Appl. 10, 054005 (2018).
[319] C. Cheng, J. Hussels, M. Niu, H.L. Bethlem, K.S.E. Eikema, E.J. Salumbides, W. Ubachs, M. Beyer, N. Hoelsch, J. A. Agner, F. Merkt, L.G. Tao, S.M. Hu, C. Jungen,
Dissociation energy of the hydrogen molecule at 10-9 accuracy
Phys. Rev. Lett. 121, 013001 (2018).
[318] M.T. Trivikram, M. Schloesser, W. Ubachs, E.J. Salumbides,
Relativistic and QED effects in the fundamental vibration of T2
Phys. Rev. Lett. 120, 163002 (2018).
[317] F.M.J. Cozijn, P. Dupre, E.J. Salumbides, K.S.E. Eikema, W. Ubachs,
Sub-Doppler frequency metrology in HD for tests of fundamental physics
Phys. Rev. Lett. 120, 153002 (2018).
[316] A. Bayerle, M.J. Deuzeman, S. van der Heijden, D. Kurilovich, T. de Faria Pinto, A. Stodolna, S. Witte, K.S.E. Eikema, W. Ubachs, R. Hoekstra, O.O. Versolato,
Sn ion energy distributions of ns- and ps-laser produced plasmas
Plasma Science Sources and Technology 27, 045001 (2018).
[315] F. Torretti, R. Schupp, D. Kurilovich, A. Bayerle, J. Scheers, W. Ubachs, R. Hoekstra, O.O. Versolato,
Short-wavelength out-of-band EUV emission from Sn laser-produced plasma
J. Phys. B 51, 045005 (2018).
[314] R.K. Altmann, L.S. Dreissen, E.J. Salumbides, W. Ubachs, K.S.E. Eikema,
Deep-ultraviolet frequency metrology of H2 for tests of molecular quantum theory
Phys. Rev. Lett. 120, 043204 (2018).
[313] D. Kurilovich, M.M. Basko, D.A. Kim, F. Torretti, R. Schupp, J.C. Visschers, J. Scheers, R. Hoekstra, W. Ubachs, O.O. Versolato,
Power-law scaling of plasma pressure on laser-ablated tin microdroplets
Physics of Plasmas 25, 012709 (2018).
[312] Y. Wang, K. Liang, W. van de Water, W. Marques Jr, W. Ubachs,
Rayleigh-Brillouin light scattering spectroscopy in nitrous oxide (N2O)
J. Quant. Spectr. Rad. Transfer 206, 63-69 (2018).
[311] W. Ubachs,
Search for varying constants of nature from astronomical observation of molecules
Space Science Reviews 214, 3 (2018).
[310] M. Schloesser, X. Zhao, M.T. Trivikram, W. Ubachs, E.J. Salumbides,
CARS spectroscopy on the (v=0-1) band in T2
J. Phys. B. 50, 214004 (2017).
[309] M. Dapra, C. Henkel, S.A. Levshakov, K.M. Menten, S. Muller, H.L. Bethlem, S. Leurini, A.V. Lapinov, W. Ubachs,
Testing the variability of the proton-to-electron mass ratio from observations of methanol in the dark cloud core L1498
Mon. Not. Roy. Astron. Soc. 472, 4434-4443 (2017).
[308] S. Spieler, M. Kuhn, J. Postler, M. Simpson, R. Wester, P. Scheier, W. Ubachs, X. Bacalla, J. Bouwman, H. Linnartz,
C60+ and the diffuse interstellar bands: An independent laboratory check
Astroph. J. 846, 168 (2017).
[307] T.M. Trivikram, R. Hakalla, A.N. Heays, M.L. Niu, S. Scheidegger, E.J. Salumbides, N. de Oliveira, R.W. Field, W. Ubachs,
Perturbations in the A1Π, v=0 state of 12C18O investigated via complementary spectroscopic techniques
Mol. Phys. 115, 3178-3191 (2017).
[306] M. Glass-Maujean, Ch. Jungen, A.-M. Vasserot, H. Schmoranzer, A. Knie, S. Kuebler, A. Ehresmann, W. Ubachs,
Experimental and theoretical studies of the npσ 1Σu+ and npπ 1Πu+ (n ≥ 4, N'=1-6) states of D2: energies, natural widths, absorption line intensities, and dynamics
J. Mol. Spectr. 338, 22-71 (2017).
[305] F. Torretti, A. Windberger, A. Ryabtsev, S. Dobrodey, H. Bekker, W. Ubachs, R. Hoekstra, E.V. Kahl, J.C. Berengut, J.R. Crespo Lopez-Urrutia, O.O. Versolato,
Optical spectroscopy of complex open 4d-shell ions Sn7+ - Sn10+
Phys. Rev. A 95, 042503 (2017).
[304] M. Bainbridge, M. Barstow, N. Reindl, L. Tchang-Brillet, T. Ayres, J. Webb, J. Barrow, J. Hu, J. Holberg, S. Preval, W. Ubachs, V. Dzuba, V. Flambaum, V. Dumont, J. Berengut,
Probing the gravitational dependence of the fine-structure constant from observations of white dwarf stars
Universe 3, 32 (2017).
[303] M. Dapra, P. Noterdaeme, M. Vonk, M.T. Murphy, W. Ubachs,
Analysis of carbon monoxide absorption at zabs = 2.5 to constrain the variation of the proton-to-electron mass ratio
Month. Not. Royal Astron. Soc. 467, 3848-3855 (2017).
[302] M.J. Deuzeman, A.S. Stodolna, E.E.B. Leerssen, A. Antoncecchi, N. Spook, T. Kleijntjens, J. Versluis, S. Witte, K.S.E. Eikema, W. Ubachs, R. Hoekstra, O.O. Versolato,
Ion distribution and ablation depth measurements of a fs-ps laser-irradiated solid tin target
J. Appl. Phys. 121, 103301 (2017).
[301] Y. Wang, Y. Yu, K. Liang, W. Marques Jr, W. van de Water, W. Ubachs,
Rayleigh-Brillouin scattering in SF6 in the kinetic regime
Chem. Phys. Lett. 669, 137-142 (2017).
[300] R. Hakalla, M.L. Niu, R. W. Field, A. Heays, E. Salumbides, G. Stark, J.R. Lyons, M. Eidelsberg, J.L. Lemaire, S.R. Federman, N. de Oliveira, W. Ubachs
Fourier-transform spectroscopy of 13C17O and deperturbation analysis of the A1Π (v=0-3) levels
J. Quant. Spectr. Rad. Transfer 189, 312-328(2017).
[299] M. Dapra, M. van der Laan, M.T. Murphy, W. Ubachs,
Constraint on a varying proton-electron mass ratio from H2 and HD at zabs=2.34
Month. Not. Roy. Astr. Soc. 465, 4057-4073 (2017).
[298] P. Noterdaeme, J.-K. Krogager, S. Balashev, J. Ge, N. Gupta, T. Kruehler, C. Ledoux, M.T. Murphy, I. Paris, P. Petitjean, H. Rahmani, R. Srianand, W. Ubachs,
Discovery of a Perseus-like cloud in the early universe; HI-to-H2 transition, carbon monoxide and small dust grains at zabs2.65 toward the quasar J0000+0048
Astron. Astroph. 597, A82 (2017).
[297] J. Biesheuvel, J.-Ph. Karr, L. Hilico, K.S.E. Eikema, W. Ubachs, J.C.J. Koelemeij,
High-precision spectroscopy of the HD+ molecule at the 1-p.p.b. level
Appl. Phys. B 123, 23 (2017).
[296] C. Cheng, A.P.P. van der Poel, P. Jansen, M. Quintero-Perez, T.E. Wall, W. Ubachs, H.L. Bethlem,
Molecular fountain
Phys. Rev. Lett. 117, 253201 (2016).
[295] W. Ubachs,
A testing time for antimatter
Science 354, 546-547 (2016).
[294] M.T. Trivikram, M. Niu, P. Wcislo, W. Ubachs, E.J. Salumbides,
Precision measurements and test of molecular theory in highly-excited vibrational states of H2(v=11)
Appl. Phys. B 122, 294 (2016).
[293] M.L. Niu, R. Hakalla, T. Madhu Trivikram, A.N. Heays, N. de Oliveira, E.J. Salumbides, W. Ubachs,
Spectroscopy and perturbation analysis of the A1Π(v=0) state of 13C16O
Mol. Phys. 114, 2857-2867 (2016).
[292] X. Bacalla, E.J. Salumbides, H. Linnartz, W. Ubachs, D. Zhao,
A spectroscopic survey of electronic transitions of C6H, 13C6H, and C6D
J. Phys. Chem. A 120, 6401-6417 (2016).
[291] W. Ubachs, J. Bagdonaite, E.J. Salumbides, M.T. Murphy, L. Kaper,
Search for a drifting proton-electron mass ratio from H2
Rev. Mod. Phys. 88, 021003 (2016).
[290] A. Windberger, F. Torretti, A. Borschevsky, A. Ryabtsev, S. Dobrodey, H. Bekker, E. Eliav, U. Kaldor, W. Ubachs, R. Hoekstra, J.R. Crespo Lopez-Urrutia, O.O. Versolato,
Analysis of the fine structure of Sn 11+ … 14+ ions by optical spectroscopy in an electron beam ion trap
Phys. Rev. A 94, 012506 (2016).
[289] D. Kurilovich, A.L. Klein, F. Torretti, A. Lassise, R. Hoekstra, W. Ubachs, H. Gelderblom, O.O. Versolato,
Plasma propulsion of a metallic micro-droplet and its deformation upon laser impact
Phys. Rev. Appl. 6, 014018 (2016).
[288] M. Dapra, M.L. Niu, E.J. Salumbides, M.T. Murphy, W. Ubachs,
Constraint on a cosmological variation in the proton-to-electron mass ratio from electronic CO absorption
Astroph. J. 826, 192 (2016).
[287] W. Ubachs, J.C.J. Koelemeij, K.S.E. Eikema, E.J. Salumbides,
Physics beyond the Standard Model from hydrogen spectroscopy
J. Mol. Spectr. 320, 1-12 (2016).
[286] R. Hakalla, M.L. Niu, E.J. Salumbides, A.N. Heays, G. Stark, J.R. Lyons, M. Eidelsberg, J.L. Lemaire, S.R. Federman, M. Zachwieja, W. Szajna, P. Kolek, I. Piotrowska, M. Ostrowska-Kopec, R. Kepa, N. de Oliveira, R.W. Field, W. Ubachs,
VIS and VUV spectroscopy of 12C17O and deperturbation analysis of the A1Π, v = 1-5 levels
Adv. Royal Soc. Chem. 6, 31588-31606 (2016).
[285] M. Glass-Maujean, Ch. Jungen, G. D. Dickenson, N. de Oliveira, W. Ubachs,
The excited J=0 1Σu+ levels of D2: Measurements and ab initio quantum defect study
J. Mol. Spectr. 320, 33-38 (2016).
[284] J. Biesheuvel, J.-Ph. Karr, L. Hilico, K.S.E. Eikema, W. Ubachs, J.C.J. Koelemeij,
Probing QED and fundamental constants through laser spectroscopy of vibrational transitions in HD+
Nature Comm. 7, 10385 (2016).
[283] M.L. Niu, E.J. Salumbides, A.N. Heays, N. de Oliveira, R.W. Field, W. Ubachs,
Spectroscopy and perturbation analysis of the CO A1Π-X1Σ+ (2,0), (3,0) and (4,0) bands
Mol. Phys. 114, 627-636 (2016).
[282] B. Witschas, O. Reitebuch, C. Lemmerz, P.G. Kableka, S. Kondratyev, Z.Y. Gu, W. Ubachs,
The measurement of tropospheric temperature profiles using Rayleigh-Brillouin scattering: Results from laboratory and atmospheric studies
EPJ Web of Conferences 119, 127004 (2016).
[281] M.L. Niu, E.J. Salumbides, W. Ubachs,
Test of quantum chemistry in vibrationally-hot hydrogen molecules
J. Chem. Phys. (Comm) 143, 081102 (2015).
[280] M. Dapra, J. Bagdonaite, M.T. Murphy, W. Ubachs,
Constraint on a varying proton-to-electron mass ratio from molecular hydrogen absorption toward quasar SDSS J123714.60+064759.5
Month. Not. Royal Astron. Soc. 454, 489-506 (2015).
[279] Z. Gu, W. Ubachs, W. Marques Jr, W. van de Water,
Rayleigh-Brillouin scattering in binary gas mixtures
Phys. Rev. Lett. 114, 243902 (2015).
[278] E.J. Salumbides, A.N. Schellekens, B. Gato-Rivera, W. Ubachs,
Constraints on extra dimensions from molecular spectroscopy
New. J. Phys. 17, 033015 (2015).
[277] J. Bagdonaite, W. Ubachs, M.T. Murphy, J.B. Whitmore,
A constraint on a varying proton-electron mass ratio 1.5 billion years after the Big Bang
Phys. Rev. Lett. 114, 071301 (2015).
[276] M. Glass-Maujean, Ch. Jungen, G. D. Dickenson, W. Ubachs, N. de Oliveira, D. Joyeux, L. Nahon,
VUV Fourier-Transform absorption study of the npπ 1Πu-, v, N - X1Σg+, v = 0, N, transitions in D2
J. Mol. Spectr. 315, 147-154 (2015).
[275] M.L. Niu, A.N. Heays, S. Jones, E.J. Salumbides, E.F. van Dishoeck, N. de Oliveira, L. Nahon, W. Ubachs,
VUV-synchrotron absorption studies of N2 and CO at 900 K
J. Mol. Spectr. 315, 137-146 (2015).
[274] M.A. Haddad, D. Zhao, H. Linnartz, W. Ubachs,
The 2Π-X2Π electronic spectra of long carbon chain (13)C2nH/D molecules for (n=4-6)
Mol. Phys. 113, 2063-2072 (2015)
[273] E.J. Salumbides, J. Bagdonaite, H. Abgrall, E. Roueff, W. Ubachs,
H2 Lyman and Werner band lines and their sensitivity for a variation of the proton-electron mass ratio in the gravitational potential of white dwarfs
Month. Not. Roy. Astron. Soc. 450, 1237-1245 (2015).
[272] N. Kanekar, W. Ubachs, K.M. Menten, J. Bagdonaite, A. Brunthaler, C. Henkel, S. Muller, H.L. Bethlem, M. Dapra,
Constraint on changes in the proton-electron mass ratio using methanol lines
Month. Not. Royal Astron. Soc. Lett. 448, L104-L108 (2015).
[271] X. Bacalla, D. Zhao, E.J. Salumbides, M.A. Haddad, H. Linnartz, W. Ubachs,
The B2Π - X2Π electronic origin band of 13C6H
J. Mol. Spectr. 308-309, 41-44 (2015).
[270] M.L. Niu, F. Ramirez, E.J. Salumbides, W. Ubachs,
High-precision laser spectroscopy of CO A1Π - X1Σ+(2,0), (3,0) and (4,0) bands
J. Chem. Phys. 142, 044302 (2015).
[270] T.J. Pinkert, O. Boll, L. Willmann, G.S.M. Jansen, E.A. Dijck, B. Groeneveld, R. Smets, F.C. Bosveld, W. Ubachs, K. Jungmann, K.S.E. Eikema, J.C.J. Koelemeij,
Effect of soil temperature on one-way optical frequency transfer through dense-wavelength-division-multiplexing fibre links
Appl. Optics 54, 728-738 (2015).
[269] A. Schulz, C. Henkel, K.M. Menten, S. Muller, D. Muders, J. Bagdonaite, W. Ubachs,
The inhomogeneous ISM toward PKS 1830-211 SW; A detailed view on molecular gas at a look-back time of 7.5 Gyr
Astron. Astroph. 574, A108 (2015).
[268] M.A. Haddad, D. Zhao, W. Ubachs,
Gas-phase electronic absorption spectra of deuterated linear seven-carbon radicals
Spectroscopy Letters 48, 567-571 (2015).
[267] E. J. Salumbides, D. Bailly, M. Vervloet, W. Ubachs,
B1Σu+ and EF1Σg+ level energies of D2
J. Mol. Spectr. 305, 34-39 (2014).
[266] J. Bagdonaite, E.J. Salumbides, S.P. Preval, M.A. Barstow, J.D. Barrow, M.T. Murphy, W. Ubachs,
Limits on a Gravitational Field Dependence of the Proton-Electron Mass Ratio from H2 in White Dwarf Stars
Phys. Rev. Lett. 113, 123002 (2014).
[265] B. Witschas, Z.Y. Gu, W. Ubachs,
Temperature retrieval from Rayleigh-Brillouin scattering profiles measured in air
Opt. Express 22, 29655-29667 (2014).
[264] W. Ubachs, E.J. Salumbides, K.S.E. Eikema, N. de Oliveira, L. Nahon,
Novel techniques in VUV high-resolution spectroscopy
J. Electr. Spectr. Related Phen. 196, 159-164 (2014).
[263] Z.Y. Gu, W. Ubachs,
A systematic study of Rayleigh-Brillouin scattering in air, N2 and O2 gases
J. Chem. Phys. 141, 104320 (2014).
[262] Z.Y. Gu, W. Ubachs, W. van de Water,
Rayleigh-Brillouin scattering of carbon dioxide
Opt. Lett. 39, 3301 (2014).
[261] T. Steimle, W. Ubachs,
Introduction to the special issue: Spectroscopic tests of fundamental physics
J. Mol. Spectr. 300, 1-2 (2014).
[260] M. Niu, E.J. Salumbides, G.D. Dickenson, K.S.E. Eikema, W. Ubachs,
Precision spectroscopy of the X1Σg+, v=0-1 (J=0-2) rovibrational splittings in H2, HD and D2
J. Mol. Spectr. 300, 44-54 (2014).
[259] E.J. Salumbides, W. Ubachs, V.I. Korobov,
Bounds on fifth forces at the sub-Angström length scale
J. Mol. Spectr. 300, 65-69 (2014).
[258] A.J. de Nijs, W. Ubachs, H.L. Bethlem,
Ramsey type microwave spectroscopy on CO (a3Π)
J. Mol. Spectr. 300, 79-85 (2014).
[257] M.R. Schmidt, J. Krelowski, G.A. Galazutdinov, D. Zhao, M.A. Haddad, W. Ubachs, H. Linnartz,
Detection of vibronic bands of C3 in a translucent cloud towards HD 169454
Month. Not. Roy. Astron. Soc. 441, 1134-1146 (2014).
[256] M.A. Haddad, D. Zhao, H. Linnartz, W. Ubachs,
Rotationally resolved spectra of the 4051 A comet band of C3 for all six 12C and 13C isotopologues
J. Mol. Spectr. 297, 41-50 (2014).
[255] G.D. Dickenson, W. Ubachs,
VUV Spectroscopic Study of the B''B1Σu+ State of H2
Mol. Phys. 112, 1089-1093 (2014).
[254] A. Heays, R. Visser, R. Gredel, W. Ubachs, B.R. Lewis, S.T. Gibson, E.F. van Dishoeck,
Isotope selective photodissociation of N2 by the interstellar radiation field and cosmic rays
Astron. Astroph. 562, A61 (2014).
[253] Y. Ma, H. Li, Z. Gu, W. Ubachs, Y. Yu, J. Huang, B. Zhou, Y. Wang, K. Liang,
Analysis of Rayleigh-Brillouin spectral profiles and Brillouin shifts in nitrogen gas and air
Opt. Express 22, 2092-2104 (2014).
[252] J. Bagdonaite, W. Ubachs, M.T. Murphy, J.B. Whitmore,
Analysis of molecular hydrogen absorption toward QSO B0642-5038 for a varying proton-to-electron mass ratio
Astroph. J. 782, 10 (2014).
[251] P. Jansen, H.L. Bethlem, W. Ubachs,
Perspective: Tipping the scales - search for drifting constants from molecular spectra
J. Chem. Phys. 140, 010901 (2014).
[250] J. Bagdonaite, M. Dapra, P. Jansen, H.L. Bethlem, W. Ubachs, S. Muller, C. Henkel, K.M. Menten,
Robust constraint on a drifting proton-to-electron mass ratio from methanol observation at three radio telescopes
Phys. Rev. Lett. 111, 231101 (2013).
[249] A. de Nijs, D. Zhao, H.L. Bethlem, H. Linnartz, W. Ubachs,
Testing the mass-scaling relations in the a3Π state of 12C18O and 13C16O
J. Mol. Spectr. 292, 20 (2013).
[248] S.B. Raghunathan, H.F. Schouten, W. Ubachs, B. Ea Kim, C.H. Gan, T.D. Visser,
Dynamic beam steering from a sub-wavelength slit by selective excitation of guided modes
Phys. Rev. Lett. 111, 153901 (2013).
[247] A. Walsh, D. Zhao, W. Ubachs, H. Linnartz,
Optomechanical shutter modulated broadband cavity-enhanced absorption spectroscopy of molecular transients of astrophysical interest
J. Phys. Chem. A 117, 9363-9369 (2013).
[246] M.L. Niu, E.J. Salumbides, D. Zhao, N. de Oliveira, D. Joyeux, L. Nahon, R.W. Field, W. Ubachs,
High resolution spectroscopy and perturbation analysis of the CO A1Π-X1Σ+ (0,0) and (1,0) bands
Mol. Phys. 111, 2163 (2013).
[245] P. Jansen, I. Kleiner, C. Meng, R. Lees, M.H.M. Janssen, W. Ubachs, H.L. Bethlem,
Prospects for high-resolution microwave spectro scopy of methanol in a Stark-deflected molecular beam
Mol. Phys. 111, 1923 (2013).
[244] X. Li, A. Heays, R. Visser, W. Ubachs, B.R. Lewis, S.T. Gibson, E.F. van Dishoeck,
Photodissociation of interstellar N2
Astron. Astroph. 555, A14 (2013).
[243] W. Ubachs, W. Vassen, E.J. Salumbides, K.S.E. Eikema,
Precision metrology on the hydrogen atom in search for new physics
Ann. Phys. (Berlin) 575, A113 (2013).
[242] F.M.J. Cozijn, J. Biesheuvel, A.S. Flores, W. Ubachs, G. Blume, A. Wicht, K. Paschke, G. Erbert, J.C.J. Koelemeij,
Laser cooling of beryllium ions using a frequency-doubled 626 nm diode laser
Opt. Lett. 38, 2370 (2013).
[241] Z. Gu, B. Witschas, W. van de Water, W. Ubachs,
Rayleigh-Brillouin scattering profiles of air at different temperatures and pressures
Appl. Optics 52, 4640 (2013).
[240] E.J. Salumbides, J.C.J. Koelemeij, J. Komasa, K. Pachucki, K.S.E. Eikema, W. Ubachs,
Bounds on fifth forces from precision measurements on molecules
Phys. Rev. D87, 112008 (2013).
[239] J. Bagdonaite, P. Jansen, C. Henkel, H.L. Bethlem, K.M. Menten, W. Ubachs,
A stringent limit on a drifting proton-to-electron mass ratio from alcohol in the early Universe
Science 339, 46 (2013).
[238] G.D. Dickenson, M.L. Niu, E.J. Salumbides, J. Komasa, K.S.E. Eikema, K. Pachucki, W. Ubachs,
Fundamental vibration of molecular hydrogen
Phys. Rev. Lett. 110, 193601 (2013).
[237] P. Jansen, L.-H. Xu, I. Kleiner, H.L. Bethlem, W. Ubachs,
Methyl mercaptan (CH3SH) as a probe for µ-variation
Phys. Rev. A87, 052509 (2013).
[236] J. Biesheuvel, D.W.E. Noom, E.J. Salumbides, K.T. Sheridan, W. Ubachs, J.C.J. Koelemeij,
Widely tunable laser frequency offset lock with 30 GHz range and 5 THz offset
Opt. Express 21, 14008-14016 (2013).
[235] Z. Gu, W. Ubachs,
Temperature-dependent bulk viscosity of nitrogen gas determined from Rayleigh-Brillouin scattering
Opt. Lett. 38, 1110 (2013).
[234] G.D. Dickenson, E.J. Salumbides, M.L. Niu, Ch. Jungen, S.R. Ross, W. Ubachs,
Precision spectroscopy of high rotational states in H2 investigated by Doppler-free two-photon laser spectroscopy in the EF1Σg+ - X1Σg+ system
Phys. Rev. A 86, 032502 (2012).
[233] T.J. Pinkert, E.J. Salumbides, M.S. Tahvili, W. Ubachs, E.A.J.M. Bente, K.S.E. Eikema,
Frequency comb generation by CW laser injection into a quantum-dot mode-locked laser
Opt. Express 20, 21357 (2012).
[232] A.J. de Nijs, W. Ubachs, H.L. Bethlem,
Sensitivity of rotational transitions in CH and CD to a possible variation of fundamental constants
Phys. Rev. A86, 032501 (2012).
[231] E.J. Salumbides, M.L. Niu, J. Bagdonaite, N. de Oliveira, D. Joyeux, L. Nahon, W. Ubachs,
The CO A-X system for constraining cosmological drift of the proton-electron mass ratio
Phys. Rev. A86, 022510 (2012).
[230] G.D. Dickenson, W. Ubachs,
The D1Π state of HD and the mass scaling relation of its predissociation
J. Phys. B. 45, 145101 (2012).
[229] J.C.J. Koelemeij, D.W.E. Noom, D. de Jong, M.A. Haddad, W. Ubachs,
Observation of the v = 8 - v = 0 vibrational overtone in cold trapped HD+
Appl. Phys. B 107, 1075-1085 (2012).
[228] S.B. Raghunathan, C.H. Gan, T. van Dijk, B. Ea. Kim, H.F. Schouten, W. Ubachs, P. Lalanne, T.D. Visser,
Plasmon switching: Observation of dynamic surface plasmon steering by selective mode excitation in a sub-wavelength slit
Opt. Express 14, 15326 (2012).
[227] A. de Lange, G.D. Dickenson, E.J. Salumbides, W. Ubachs, N. de Oliveira, D. Joyeux, L. Nahon,
VUV Fourier-transform absorption study of the Lyman and Werner bands in D2
J. Chem. Phys. 136, 234310 (2012).
[226] Z. Gu, M.O. Vieitez, E.-J. van Duijn, W. Ubachs,
A Rayleigh-Brillouin scattering spectrometer for ultraviolet wavelengths
Rev. Scient. Instrum. 83, 053112 (2012).
[225] M.A. Haddad, D. Zhao, H. Linnartz, W. Ubachs,
Spin-orbit splitting and lifetime broadening in the A2Δ state of l-C5H
Chin. J. Chem. Phys. 25, 129 (2012).
[224] J. Bagdonaite, M.T. Murphy, L. Kaper, W. Ubachs,
Constraint on a variation of the proton-to-electron mass ratio from H2 absorption towards quasar Q2348-011
Month. Not. Roy. Astron. Soc. 421, 419-425 (2012).
[223] V.V. Ilyushin, P. Jansen, M.G. Kozlov, S.A. Levshakov, I. Kleiner, W. Ubachs, H.L. Bethlem,
Sensitivity to a possible variation of the proton-to-electron mass ratio of torsion-wagging-rotation transitions in methylamine (CH3NH2)
Phys. Rev. A 85, 032505 (2012).
[222] D. Zhao, H. Linnartz, W. Ubachs,
The electronic spectrum of the Cs-C11H3 radical
J. Chem. Phys. 136, 054307 (2012).
[221] J. Liu, D. Sprecher, F. Merkt, E.J. Salumbides, W. Ubachs,
Determination of the ionization and dissociation energies of H2 and He2
AIP. Conf. Proc. 1504, 495 (2012).
[220] H.L. Bethlem, P. Jansen, W. Ubachs,
Testing the time-invariance of fundamental constants using cold and not-so-cold molecules
AIP. Conf. Proc. 1504, 454 (2012).
[219] D.Z. Kandula, C. Gohle, T.J. Pinkert, W. Ubachs, K.S.E. Eikema,
XUV frequency comb metrology on the ground state of helium
Phys. Rev. A84, 062512 (2011).
[218] A.N. Heays, G. Dickenson, E.J. Salumbides, N. de Oliveira, D. Joyeux, L. Nahon, B.R. Lewis, W. Ubachs,
High-resolution Fourier-transform XUV photoabsorption spectroscopy study of 14N15N
J. Chem. Phys. 135, 244301 (2011).
[217] P. Jansen, I. Kleiner, L.-H. Xu, W. Ubachs, H.L. Bethlem,
Sensitivity of transitions in internal rotor molecules to a possible variation of the proton-to-electron mass ratio
Phys. Rev. A 84, 062505 (2011).
[216] G. Dickenson, T. Ivanov, W. Ubachs, M. Roudjane, N. de Oliveira, D. Joyeux, L. Nahon, W.U.L. Tchang-Brillet, M. Glass-Maujean, H. Schmoranzer, A. Knie, S. Kubler, A. Ehresmann,
VUV spectroscopic study of the D1Πu state of molecular deuterium
Mol. Phys. 109, 2693-2708 (2011).
[215] A.J. de Nijs, E.J. Salumbides, K.S.E. Eikema, W. Ubachs, H.L. Bethlem,
UV frequency metrology on CO (a3Π); Isotope effects and sensitivity to a variation of the proton-to-electron mass ratio
Phys. Rev. A 84, 052509 (2011).
[214] J.A. King, M.T. Murphy, W. Ubachs, J.K. Webb,
New constraint on cosmological variation of the proton-to-electron mass ratio from Q0528-250
Mon. Not. Royal Astron. Soc. 417, 3010-3024 (2011).
[213] D. Zhao, M.A. Haddad, H. Linnartz, W. Ubachs,
C6H and C6D: electronic spectra and Renner-Teller analysis
J. Chem. Phys. 135, 044307 (2011).
[212] D. Zhao, M.A. Haddad, H. Linnartz, W. Ubachs,
Structure determination of the non-linear hydrocarbon chains C9H3 and C11H3 by deuterium labeling
J. Chem. Phys. 135, 074201 (2011).
[211] E.J. Salumbides, G. Dickenson, T.I. Ivanov, W. Ubachs,
QED effects in molecules: test on rotational quantum states of H2
Phys. Rev. Lett. 107, 043005 (2011).
[210] F. van Weerdenburg, M.T. Murphy, A.L. Malec, L. Kaper, W. Ubachs,
First constraint on cosmological variation of the proton-to-electron mass ratio from two independent telescopes
Phys. Rev. Lett. 106, 180802 (2011).
[209] P. Jansen, L.-H. Xu, I. Kleiner, W. Ubachs, H.L. Bethlem,
Methanol as a sensitive probe for spatial and temporal variations of the proton-to-electron mass ratio
Phys. Rev. Lett. 106, 100801 (2011).
[208] D. Sprecher, Ch. Jungen, W. Ubachs, F. Merkt,
Towards measuring the ionisation and dissociation energies of molecular hydrogen with sub-MHz accuracy
Faraday Discussions 150, 51-70 (2011).
[207] W. Ubachs, J. Bagdonaite, M.T. Murphy, R. Buning, L. Kaper,
Search for cosmological µ variation from high-redshift H2 absorption; a status report
Astrophys. Space Science; C. Martins and P. Molaro (eds.), From Varying Couplings to Fundamental Physics, p125 (2011).
[206] T.I. Ivanov, C.A. de Lange, W. Ubachs,
Spectral identification of diffuse resonances in H2 above the n=2 dissociation limit
J. Chem. Phys. 134, 054309 (2011).
[205] E.J. Salumbides, V. Maslinskas, I.M. Dildar, A.L. Wolf, E.-J. van Duijn, K.S.E. Eikema, W. Ubachs,
High precision frequency measurement of the 423 nm Ca I line
Phys. Rev. A83, 012502 (2011).
[204] F. Hamann, N. Kanekar, J.X. Prochaska, M.T. Murphy, S.L. Ellison, A.L. Malec, N. Milutinovic, W. Ubachs,
A high-velocity narrow absorption line outflow in the quasar J212329.6-005052.9
Month. Not. Roy. Astron. Soc. 410, 1957-1974 (2011).
[203] A.L. Wolf, J. Morgenweg, J.C.J. Koelemeij, S.A. van den Berg, W. Ubachs, K.S.E. Eikema,
Direct frequency-comb spectroscopy of a dipole-forbidden clock transition in trapped 40Ca+ ions
Opt. Lett. 36, 49-51 (2011).
[202] D. Zhao, N. Wehres, H. Linnartz, W. Ubachs,
Electronic spectra and structure of the non-linear carbon chain C9H3
Chem. Phys. Lett. 501, 232-237 (2011).
[201] K.S.E. Eikema, W. Ubachs,
Precision Laser spectroscopy in the Extreme Ultraviolet
Handbook of high resolution spectroscopy, Eds. M. Quack and F. Merkt,
John Wiley & Sons, Page 1373-1413 (2010).
[200] D.Z. Kandula, C. Gohle, T.J. Pinkert, W. Ubachs, K.S.E. Eikema,
Extreme ultraviolet frequency comb metrology
Phys. Rev. Lett. 105, 063001 (2010).
[199] G. Dickenson, T. Ivanov, M. Roudjane, N. de Oliveira, D. Joyeux, L. Nahon, L. Tchang-Brillet, M. Glass-Maujean, I. Haar, A. Ehresmann, W. Ubachs,
Synchrotron VUV radiation studies of the D1Πu state of H2
J. Chem. Phys. 133, 144317 (2010).
[198] N. Wehres, D. Zhao, W. Ubachs, H. Linnartz,
Rotationally resolved A3Σu-- X3Σu- spectrum of HC7H
Chem. Phys. Lett. 497, 30-32 (2010).
[197] M.O. Vieitez, E.-J. van Duijn, W. Ubachs, B. Witschas, A. Meijer, A.S. de Wijn, N. Dam, W. van de Water,
Coherent and spontaneous Rayleigh-Brillouin scattering in molecular gases and gas mixtures
Phys. Rev. A 82, 043836 (2010).
[196] D. Sprecher, J. Liu, Ch. Jungen, W. Ubachs, F. Merkt,
Determination of ionization and dissociation energies of HD
J. Chem. Phys. 133, 111102 (2010).
[195] J. Tumlinson, A.L. Malec, R.F. Carswell, M.T. Murphy, R. Buning, N. Milutinovic, S.L. Ellison, J.X. Prochaska, R.A. Jorgenson, W. Ubachs, A.M. Wolfe,
Cosmological concordance or chemical coincidence ? Deuterated molecular hydrogen abundances at high redshift
Astroph. J. Lett. 718, L156 (2010).
[194] B. Witschas, M.O. Vieitez, E.-J. van Duijn, O. Reitebuch, W. van de Water, W. Ubachs,
Spontaneous Rayleigh-Brillouin scattering of ultraviolet light in nitrogen, dry and moist air
Appl. Optics 49, 4217-4227 (2010).
[193] J. Liu, D. Sprecher, Ch. Jungen, W. Ubachs, F. Merkt,
Determination of ionization and dissociation energies of the deuterium molecule (D2)
J. Chem. Phys. 132, 154301 (2010).
[192] T. van Dijk, H.F. Schouten, W. Ubachs, T.D. Visser,
The Pancharatnam-Berry phase for non-cyclic polarization changes
Opt. Express 18, 10796-10804 (2010).
[191] T.I. Ivanov, G.D. Dickenson, M. Roudjane, N. de Oliveira, D. Joyeux, L. Nahon, W.U.L. Tchang-Brillet, W. Ubachs,
Fourier-transform spectroscopy of HD in the vacuum ultraviolet at λ = 87-112 nm
Mol. Phys. 108, 771-786 (2010).
[190] D. Bailly, E.J. Salumbides, M. Vervloet, W. Ubachs,
Accurate level energies in the EF1Σ+g, GK1Σ+g, H1Σ+g, B1Σ+u, C1Πu, B'1Σ+u, D1Πu, I1Πg, J1Δg states of H2
Mol. Phys. 108, 827-846 (2010).
[189] A.L. Malec, R. Buning, M.T. Murphy, N. Milutinovic, S.L. Ellison, J.X. Prochaska, L. Kaper, J. Tumlinson, R.F. Carswell, W. Ubachs,
Keck telescope constraint on cosmological variation of the proton-to-electron mass ratio
Month. Not. Royal Astron. Soc., 403, 1541-1555 (2010).
[188] A.L. Malec, R. Buning, M.T. Murphy, N. Milutinovic, S.L. Ellison, J.X. Prochaska, L. Kaper, J. Tumlinson, R.F. Carswell, W. Ubachs,
New limit on a varying proton-to-electron mass ratio from high resolution optical quasar spectra
Mem. Soc. Astron. Italiana 80, 882 (2009).
[187] M.O. Vieitez, T.I. Ivanov, E.Reinhold, C.A. de Lange, W. Ubachs,
Spectroscopic observation and characterization of H+H- heavy Rydberg states
J. Phys. Chem. A 113, 13237-13245 (2009).
[186] R. Haselberg, L. van der Sneppen, F. Ariese, W. Ubachs, C. Gooijer, G.J. de Jong, G.W. Somsen,
Effectiveness of charged non-covalent polymer coatings against protein adsorption to silica surfaces studied by evanescent-wave cavity ring-down spectroscopy and capillary electrophoresis
Anal. Chem. 81, 10172-10178 (2009).
[185] M.J.R. Heck, E. Salumbides, A. Renault, E.A.J.M. Bente, Y.-S. Oei, M.K. Smit, R. Notzel, R. van Veldhoven, K.S.E. Eikema, W. Ubachs,
Analysis of hybrid mode-locking of two-section quantum dot lasers operating at 1.5 micron
Opt. Express 17, 18063 (2009).
[184] J. Liu, E.J. Salumbides, U. Hollenstein, J.C.J. Koelemeij, K.S.E. Eikema, W. Ubachs, F. Merkt,
Determination of ionization and dissociation energies of the hydrogen molecule
J. Chem. Phys. 130, 174306 (2009).
[183] D. Ityaksov, S. Stolte, H. Linnartz, W. Ubachs,
Rotational analysis of the A2Σ+ (v=1,2) - X2Π (v=0) electronic bands of 15N18O
J. Mol. Spectr. 255, 139-143 (2009).
[182] L. van der Sneppen, F. Ariese, C. Gooijer, W. Ubachs,
Liquid-Phase and Evanescent Wave Ring-Down spectroscopy in analytical chemistry
Ann. Rev. Anal. Chem. 2, 13-35 (2009).
[181] L. van der Sneppen, C. Gooijer, W. Ubachs, F. Ariese,
Evanescent Wave Cavity Ring-Down detection of cytochrome c on surface-modified prisms
Sensors and Actuators B 139, 505-510 (2009).
[180] A.L. Wolf, S.A. van den Berg, W. Ubachs, K.S.E. Eikema,
Direct frequency comb spectroscopy of trapped ions
Phys. Rev. Lett. 102, 223901 (2009).
[179] M.J.R. Heck, A. Renault, E.A.J.M. Bente, Y.-S. Oei, M.K. Smit, K.S.E. Eikema, W. Ubachs, A. Anantathanasarn, R. Notzel,
Passively mode-locked 4.6 GHz and 10.5 GHz quantum dot laser diodes around 1.55 micron with large operating regime
IEEE J. Select. Top. Quant. Electr. 15, 634-643 (2009).
[178] H.L. Bethlem, W. Ubachs,
Testing the time invariance of fundamental constants using microwave spectroscopy on diatomic radicals
Faraday Disc. 142, 25-36 (2009).
[177] E.J. Salumbides, A. Khramov, W. Ubachs,
High-resolution 2+1 REMPI study of the a'' 1Σg+ state in N2
J. Phys. Chem. A 113, 2383-2386 (2009).
[176] L. van der Sneppen, C. Gooijer, W. Ubachs, F. Ariese,
Cavity Ring-Down spectroscopy in analytical chemistry
In: Cavity Ring-Down Spectroscopy; Techniques and Applications
Eds. G. Berden and R. Engeln, Blackwell Publishing (Wiley), p. 89-112 (2009).
[175] E.J. Salumbides, D. Bailly, A. Khramov, A.L. Wolf, K.S.E. Eikema, M. Vervloet, W. Ubachs,
Improved laboratory values of the H2 Lyman and Werner lines for constraining time variation of the proton-to-electron mass ratio
Phys. Rev. Lett. 101, 223001 (2008).
[174] M.O. Vieitez, T.I. Ivanov, E.Reinhold, C.A. de Lange, W. Ubachs,
Observation of a Rydberg series in H+H-: A heavy Bohr atom
Phys. Rev. Lett. 101, 163001 (2008).
[173] B.R. Lewis, K.G.H. Baldwin, A.N. Heays, S.T. Gibson, J.P. Sprengers, W. Ubachs, M. Fujitake,
Structure and predissociation of the 3pσu D3Σu+ state of N2; First extreme ultraviolet and new near-infrared observations with coupled-channels analysis
J. Chem. Phys. 129, 204303 (2008).
[172] D. Ityaksov, H. Linnartz, W. Ubachs,
Deep-UV Rayleigh Scattering of N2, CH4 and SF6
Mol. Phys. 106, 2471-2479 (2008).
[171] J.N. Philippson, R.C. Shiell, E. Reinhold, W. Ubachs,
Observation of molecular hyperfine structure in the XUV: the HF C-X spectrum
J. Chem. Phys. 129, 174310 (2008).
[170] B.R. Lewis, K.G.H. Baldwin, J.P. Sprengers, W. Ubachs, G. Stark, K. Yoshino,
Optical observation of C, F, and G 3Πu states of N2
J. Chem. Phys. 129, 164305 (2008).
[169] H.L. Bethlem, M. Kajita, B. Sartakov, G. Meijer, W. Ubachs,
Prospects for precision measurements on ammonia molecules in a molecular fountain
Eur. Phys. Journal Special Topics 163, 55-69 (2008).
[168] M. Roudjane, T.I. Ivanov, M.O. Vieitez, C.A. de Lange, W.U.L. Tchang-Brillet, W. Ubachs,
Extreme ultraviolet laser calibration of D2 Lyman and Werner transitions
Mol. Phys. 106, 1193-1197 (2008).
[167] A.L. Wolf, S.A. van den Berg, Ch. Gohle, E.J. Salumbides, W. Ubachs, K.S.E. Eikema,
Frequency metrology on the 4s 2S1/2 - 4p 2P1/2 transition in 40Ca+ for comparison with quasar data
Phys. Rev. A 78, 032511 (2008).
[166] T.I. Ivanov, E.J. Salumbides, M.O. Vieitez, P.C. Cacciani, C.A. de Lange, W. Ubachs,
Extreme ultraviolet laser metrology of O I transitions
Month. Not. Roy. Astron. Soc. Letters 389, L4-L7 (2008).
[165] T.I. Ivanov, M. Roudjane, M.O. Vieitez, C.A. de Lange, W.U.L. Tchang-Brillet, W. Ubachs,
On a variation of the proton-electron mass ratio HD as a probe for detecting mass variation on a cosmological time scale
Phys. Rev. Lett. 100, 093007 (2008).
[164] D. Ityaksov, H. Linnartz, W. Ubachs,
Deep-UV absorption and Rayleigh scattering of carbon dioxide
Chem. Phys. Lett. 462, 31-34 (2008).
[163] D.Z. Kandula, A. Renault, Ch. Gohle, A.L. Wolf, S. Witte, W. Hogervorst, W. Ubachs, K.S.E. Eikema,
Ultrafast double-pulse parametric amplification for precision Ramsey metrology
Opt. Express 16, 7071-7082 (2008).
[162] M.O. Vieitez, T.I. Ivanov, C.A. de Lange, W. Ubachs, A.N. Heays, B.R. Lewis, G. Stark,
Interactions of the 3pπu c1Πu(v=2) Rydberg-complex member in isotopic N2
J. Chem. Phys. 128 134313 (2008).
[161] F. Brandi, F. Giammanco, W. Ubachs,
Plasma-dynamically induced frequency shifts in high-order harmonic generation in nitrogen
Laser Physics 18, 585-591 (2008).
[161] M.O. Vieitez, T.I. Ivanov, W. Ubachs, B.R. Lewis, C.A. de Lange,
On the complexity of the absorption spectrum of molecular nitrogen
J. Molecular Liquids 141, 110-117 (2008).
[160] E.J. Salumbides, K.S.E. Eikema, W. Ubachs, U. Hollenstein, H. Knoeckel, E. Tiemann,
Improved potentials and Born-Oppenheimer corrections by new measurements of transitions of 129I2 and 127I 129I in the B3Πu - X1Σg band system
Eur. Phys. J. D 47, 171-179 (2008).
[159] L. van der Sneppen, J. B. Buijs, C. Gooijer, W. Ubachs, F. Ariese
Evanescent-wave cavity ring-down spectroscopy for enhanced detection of surface binding under flow injection analysis
Appl. Spectr. 62, 649-654 (2008).
[158] T.I. Ivanov, M.O. Vieitez, C.A. de Lange, W. Ubachs,
Frequency calibration of B1Σu+ - X1Σg+ (6,0) Lyman lines in H2 for comparison with quasar data
J. Phys. B 41, 035702 (2008).
[157] S. Hannemann, E.-J. van Duijn, W. Ubachs,
A narrow-band injection-seeded pulsed titanium: sapphire oscillator-amplifier system with on-line chirp analysis for high-resolution spectroscopy
Rev. Sci. Instrum. 78, 103102 (2007).
[156] W. Ubachs, R. Buning, K.S.E. Eikema, E. Reinhold,
On a possible variation of the proton-electron mass ratio; H2 spectra in the line of sight of high-redshift quasars and in the laboratory
J. Mol. Spectr. 241, 155-179 (2007).
[155] M.O. Vieitez, T.I. Ivanov, J.P. Sprengers, C.A. de Lange, W. Ubachs, B.R. Lewis, G. Stark
Quantum-interference effects in the o1Πu(v=1) - b1Πu(v=9) Rydberg-valence complex of molecular nitrogen
Mol. Phys. 105, 1543-1557 (2007).
[154] S. Hannemann, E.J. Salumbides, W. Ubachs,
Reducing the first order Doppler shift in a Sagnac interferometer
Opt. Lett. 32, 1381-1383 (2007).
[153] L. van der Sneppen, F. Ariese, C. Gooijer, W. Ubachs,
Cavity ring-down spectroscopy for detection in liquid chromatography at UV wavelengths using standard cuvettes in a zero-degree geometry
J. Chromatogr. A 1148, 184-188 (2007).
[152] E. Reinhold, R. Buning, U. Hollenstein, A. Ivanchik, P. Petitjean, W. Ubachs,
Indication of a cosmological variation of the proton-electron mass ratio based on laboratory measurement and reanalysis of H2 spectra
Phys. Rev. Lett. 96, 151101 (2006).
[151] S. Hannemann, E.J. Salumbides, S. Witte, R. Zinkstok, E.-J. van Duijn, K.S.E. Eikema, W. Ubachs,
Frequency metrology on the EF1Σ+g- X1Σ+g transition in H2, HD and D2
Phys. Rev. A 74, 062514 (2006).
[150] W. Ubachs
Precision spectroscopy of H2 and a possible variation of mp/me over cosmological time
AIP Conf. Proc. 869, 37 (2006).
[149] E.J. Salumbides, S. Hannemann, K.S.E. Eikema, W. Ubachs,
Isotopically-resolved calibration of the 285-nm Mg I resonance line for comparison with quasar absorptions
Mon. Notices Roy. Astron. Soc. 373. L41-L44 (2006).
[148] S. Witte, R. Th. Zinkstok, A.L. Wolf, W. Hogervorst, W. Ubachs, K.S.E. Eikema,
A source of 2 terawatt, 2.7 cycle laser pulses based on noncollinear optical parametric chirped amplification
Opt. Express 14, 8168-8177 (2006).
[147] S. Hannemann, E.J. Salumbides, S. Witte, R. Zinkstok, E.-J. van Duijn, K.S.E. Eikema, W. Ubachs,
Frequency metrology on the Mg 3s2 - 3s4p line for comparison with quasar data
Phys. Rev. A 74, 012505 (2006).
[146] R.T. Zinkstok, S. Witte, W. Ubachs, W. Hogervorst, K.S.E. Eikema,
Frequency comb metrology laser spectroscopy in the vacuum ultraviolet
Phys. Rev. A 73, 061801(R) (2006).
[145] L. van der Sneppen, A.E. Wiskerke, F. Ariese, C. Gooijer, W. Ubachs,
Cavity ring-down spectroscopy for detection in liquid chromatography: extension to tunable sources and UV wavelengths
Appl. Spectr. 60, 931-935 (2006).
[144] E.J. Salumbides, K.S.E. Eikema, W. Ubachs, U. Hollenstein, H. Knoeckel, E. Tiemann,
The hyperfine structure of 129I2 and 127I129I in the B3Πu - X1Σg band system
Mol. Phys. 104, 2641-2652 (2006).
[143] O. Naumenko, M. Sneep, M. Tanaka, S.V. Shirin, W. Ubachs, J. Tennyson,
Cavity ring-down spectroscopy of H217O in the range 16570 -17125 cm-1
J. Mol. Spectr. 237, 63-69 (2006).
[142] U. Hollenstein, E. Reinhold, C.A. de Lange, W. Ubachs,
High resolution VUV-laser spectroscopic study of the B1Σ(u)+ (v') - X1Σ(g)+ (0), v'=0-2 Lyman bands in H2 and HD
J. Phys. B. 39, L195-L201 (2006).
[141] F. Brandi, F. Giammanco, W. Ubachs
Spectral redshift in harmonic generation from plasma dynamics in the laser focus
Phys. Rev. Lett. 96, 123904 (2006).
[140] L. van der Sneppen, A.E. Wiskerke, F. Ariese, C. Gooijer, W. Ubachs,
Improving absorbance detection in liquid chromatography with cavity ring-down spectroscopy
Anal. Chim. Acta 558, 2-6 (2006).
[139] J.P. Sprengers, W. Ubachs
Lifetimes and transition frequencies of several singlet ungerade states in N2 between 100000 - 106000 cm-1
J. Mol. Spectr. 235, 176-180 (2006).
[138] M. Sneep, D. Ityaksov, I. Aben, H. Linnartz, W. Ubachs,
Temperature dependent cross sections of O2-O2 collision-induced absorption resonances at 477 nm and 577 nm
J. Quant. Spectr. Rad. Transfer, 98, 405-424 (2006).
[137] R.C. Shiell, E. Reinhold, F. Magnus, W. Ubachs,
Control of diabatic vs. adiabatic field dissociation in a heavy Rydberg system
Phys. Rev. Lett. 95, 213002 (2005).
[136] S. Witte, R.T. Zinkstok, W. Ubachs, W. Hogervorst, K.S.E. Eikema
Deep ultraviolet quantum-interference metrology with ultrashort laser pulses
Science 307, 400-403 (2005).
[135] B.R. Lewis, S.T. Gibson, J.P. Sprengers, W. Ubachs, A. Johansson, C.-G. Wahlstrom,
Lifetime and predissociation yield of 14N2 b1Πu (v=1) revisited: effects of rotation
J. Chem. Phys. 123, 236101 (2005).
[134] E.J. Salumbides, J.P. Sprengers, E. Reinhold, W. Ubachs
High precision frequency calibration of N I lines in the XUV domain
J. Phys. B 38, L383-L387 (2005).
[133] S. Hannemann, G.R. Wu, E.-J. van Duijn, W. Ubachs, Ph. Cosby,
Pressure broadening and fine-structure dependent predissociation in oxygen B3Σu-, v=0
J. Chem. Phys. 123, 174318 (2005).
[132] L. K. Cheng, R. Koops, A. Wielders, W. Ubachs
Alternative fringe sensor for DARWIN mission
Proc. SPIE Int. Soc. Opt. Eng. 5905, 59051E (2005).
[131] L. K. Cheng, R. Koops, A. Wielders, W. Ubachs
Development of a fringe sensor based on 3x3 fiber optic coupler for space interferometry
Proc. SPIE Int. Soc. Opt. Eng. 5855, 1004 (2005).
[130] J.P. Sprengers, E. Reinhold, W. Ubachs, K.G.H. Baldwin, B.R. Lewis
Optical observation of the 3sσg F3Πu Rydberg state of N2
J. Chem. Phys. 123, 144315 (2005).
[129] S. Hannemann, U. Hollenstein, E.-J. van Duijn, W. Ubachs,
Production of narrowband tunable XUV radiation by non-collinear resonance enhanced four-wave mixing
Opt. Lett. 30, 1494-1496 (2005).
[128] S. Hannemann, E.-J. van Duijn, W. Ubachs,
Deep-UV high resolution cavity ring-down spectroscopy of the Schumann-Runge bands in 16O2 and 18O2 at wavelengths 197 - 203 nm
J. Mol. Spectr. 232, 33-38 (2005).
[127] I. Labazan, E. Reinhold, W. Ubachs, V.V. Flambaum,
Wavelength calibration of the C I line at 94.5 nm for comparison with quasar data
Phys. Rev. A 71, 040501(R) (2005).
[126] B. Bahnev, L. van der Sneppen, A.E. Wiskerke, F. Ariese, C. Gooijer, W. Ubachs,
Miniaturized Cavity Ring-Down detection in a liquid flow cell
Anal. Chem. 77, 1188-1191 (2005).
[125] I. Velchev, W. Ubachs,
Statistical properties of the Stokes signal in stimulated Brillouin scattering pulse compressors
Phys. Rev. A 71, 043810 (2005).
[124] J.P. Sprengers, W. Ubachs, K.G.H. Baldwin,
Isotopic variation of experimental lifetimes for the lowest 1Πu states in N2
J. Chem. Phys. 122, 144301 (2005).
[123] E. Reinhold, W. Ubachs,
Heavy Rydberg states
Mol. Phys. 103, 1329-1352 (2005).
[122] F. Giammanco, A. Pirri, F. Brandi, M. Barkaus kas, W. Ubachs,
Measurements of chirp-induced frequency shift in high-harmonic generation in xenon
Laser Physics 15, 328-333 (2005).
[121] M. Barkauskas, F. Brandi, F. Giammanco, D. Neshev, A. Pirri, W. Ubachs,
A novel-type tunable and narrowband extreme ultraviolet radiation source based on high-harmonic conversion of picosecond laser pulses
J. Electr. Spectr. Rel. Phen. 144-147, 1151-1155 (2005).
[120] W. Ubachs
High resolution molecular physics studies using a laser-based tunable XUV source at 107 resolving power
J. Electr. Spectr. Rel. Phen. 144-147, 97-101 (2005).
[119] M. Sneep, W. Ubachs,
Direct measurement of the Rayleigh scattering cross section in various gases
J. Quant. Spectr. Rad. Transfer 92, 293-310 (2005).
[118] W. Ubachs, E. Reinhold,
Highly accurate H2 Lyman and Werner band laboratory measurements and an improved constraint on a cosmological variation of the proton-to-electron mass-ratio
Phys. Rev. Lett. 92, 101302 (2004).
[117] M. Eidelsberg, F. Launay, K. Ito, T. Matsui, P.C. Hinnen, E. Reinhold, W. Ubachs, K.P. Huber,
Rydberg-valence interactions of CO, and spectroscopic evidence characterizing the C'1Σ+ valence state
J. Chem. Phys. 121, 292-308 (2004).
[116] M. Sneep, S. Hannemann, E.-J. van Duijn, W. Ubachs
Deep-UV Cavity Ring-Down Spectroscopy
Opt. Lett. 29, 1378-1380 (2004).
[115] J. Philip, J.P. Sprengers, Th. Pielage, C.A. de Lange, W. Ubachs, E. Reinhold,
Highly accurate transition frequencies in the H2 Lyman and Werner absorption bands
Can. J. Chem. 82, 713-722 (2004).
[114] M. Tanaka, M. Sneep, W. Ubachs, J. Tennyson,
Cavity-Ring-Down Spectroscopy of H218O in the 16570 -- 17120 cm-1 frequency range
J. Mol. Spectr. 226, 1-6 (2004).
[113] J.P. Sprengers, A. Johansson, A. L'Huillier, C.-G. Wahlstrom, B.R. Lewis, W. Ubachs,
Pump-probe lifetime measurements on singlet ungerade states in molecular nitrogen
Chem. Phys. Lett. 389, 348-351 (2004).
[112] J.P. Sprengers, W. Ubachs, A. Johansson, A. L'Huillier, C.-G. Wahlstrom, R. Lang, B.R. Lewis, S.T. Gibson,
Lifetime and predissociation yield of 14N2 b1Πu (v=1)
J. Chem. Phys. 120, 8973-8978 (2004).
[111] P. Cacciani, W. Ubachs
High resolution study of Q-branches in the E1Π - X1Σ+ (0,0) band of 12C16O, 13C16O and 13C18O
J. Mol. Spectr. 225, 62-65 (2004).
[110] J. Philip, J.P. Sprengers, P. Cacciani, C.A. de Lange, W. Ubachs,
Frequency-mixing scheme for the production of tunable narrowband XUV radiation (91-95 nm)
Appl. Phys. B 78, 737-743 (2004).
[109] E. Witkowicz, H. Linnartz, C.A. de Lange, W. Ubachs, A. Sfounis, M. Massaouti, M. Velegrakis,
Mass spectrometric and laser spectroscopic characterization of a supersonic planar plasma expansion
Int. J. Mass Spectr. 232, 25-29 (2004).
[108] F. Brandi, D. Neshev, W. Ubachs,
High-order harmonic generation yielding tunable extreme-ultraviolet radiation of high spectral purity
Phys. Rev. Lett. 91, 163901 (2003).
[107] G. Greetham, U. Hollenstein, R. Seiler, W. Ubachs, F. Merkt
High resolution VUV photoionization spectroscopy of HD between the X2Σg+, v+=0 and v+=1 thresholds
Phys. Chem. Chem. Phys. 5, 2528-2534 (2003).
[106] J.P. Sprengers, W. Ubachs, K.G.H. Baldwin, B.R. Lewis, W.-U.L. Tchang-Brillet,
Extreme ultraviolet laser excitation of isotopic molecular nitrogen: the dipole allowed spectrum of 15N2 and 14N15N
J. Chem. Phys. 119, 3160-3173 (2003).
[105] F. Brandi, I. Velchev, D. Neshev, W. Hogervorst, W. Ubachs,
A novel narrow-band wavelength-tunable laser system delivering 300 ps high-energy pulses in the near-infrared
Rev. Sci. Instr. 74, 32-37 (2003).
[104] J.C.J. Koelemeij, A. de Lange, W. Ubachs,
Search for outer-well states above the ionization potential in H2
Chem. Phys. 287, 349-354 (2003).
[103] M. Sneep, W. Ubachs,
Cavity-Ring down measurement of the O2-O2 collision-induced absorption resonance at 477 nm at sub-atmospheric pressures
J. Quant. Spectr. Rad. Transfer 78, 171-178 (2003).
[102] M. Sneep, W. Ubachs,
Cavity-Ring down spectroscopy of O2-O2 collisional induced absorption
In: Weakly Interacting Molecular Pairs: Unconventional Absorbers of Radiation in the Atmosphere,
NATO Science series: IV: Earth and Environmental sciences Vol 27; eds. C. Camy-Peret, A. Vigasin (2003).
[101] E. Reinhold, W. Ubachs,
Observation of coherent wave packets in a heavy Rydberg system
Phys. Rev. Lett. 88, 013001 (2002).
[100] F. Brandi, W. Hogervorst, W. Ubachs,
High resolution vacuum-ultraviolet and ultraviolet photoionization spectroscopy of krypton
J. Phys. B 35, 1071-1084 (2002).
[99] P. Cacciani, F. Brandi, J.P. Sprengers, A. Johansson, A. L'Huillier, C.-G. Wahlstrom, W. Ubachs,
Predissociation of the 4pp L1Π Rydberg state of carbon monoxide
Chem. Phys. 282, 63-73 (2002).
[98] G. Berden, G. Meijer, W. Ubachs,
Spectroscopic Applications using Ring-Down cavities
In: Cavity Enhanced Spectroscopies; Eds: Van Zee, Looney, Academic Press (2002)
Experimental Methods in the Physical Sciences Vol. 40, 47-82 (2002).
[97] A. de Lange, R. Lang, W.J. van der Zande, W. Ubachs,
Highly excited states of gerade symmetry in molecular nitrogen
J. Chem. Phys. 116, 7893-7901 (2002).
[96] Th. Pielage, A. de Lange, F. Brandi, W. Ubachs,
Bound energy levels at the n=2 dissociation threshold in HD
Chem. Phys. Lett. 366, 583-587 (2002).
[95] R. Lang, A.N. Maurellis, W.J. van der Zande, I. Aben, J. Landgraf, W. Ubachs,
Forward modeling and retrieval of water vapor from GOME: Treatment of narrow band absorption spectra
J. Geoph. Res. 107 D001453 (2002).
[94] A. de Lange, E. Reinhold, W. Ubachs
Phenomena of g-u symmetry-breakdown in HD
Intern. Rev. Phys. Chemistry 21, 257-275 (2002).
[93] A. de Lange, E. Reinhold, W. Ubachs,
Precision spectroscopy on some g symmetry states in H2 and determination of the ionization potential
Phys. Rev. A 65, 064501 (2002).
[92] A. de Lange, W. Hogervorst, W. Ubachs, L. Wolniewicz,
Double-well states of ungerade symmetry in H2; first observation and ab initio calculation
Phys. Rev. Lett. 86, 2988-2991 (2001).
[91] H. Naus, I.H.M. van Stokkum, W. Hogervorst, W. Ubachs,
Quantitative analysis of decay transients applied to a multi-mode pulsed cavity ring-down experiment
Appl. Optics 40, 4416-4426 (2001).
[90] W. Ubachs, R. Lang, I. Velchev, W.-U L. Tchang-Brillet, A. Johansson, Z.S. Li, V. Lokhnygin, C.-G. Wahlström,
Lifetime measurements on the c4' 1Σu+, v=0, 1 and 2 states of molecular nitrogen
Chem. Phys. 270, 215-225 (2001).
[89] F. Brandi, I. Velchev, W. Hogervorst, W. Ubachs,
High-resolution VUV spectroscopy of Xe hyperfine splittings, isotope shifts and isotope dependent ionization energies
Phys. Rev. A 64, 032505 (2001).
[88] P. Cacciani, F. Brandi, I. Velchev, C. Lynga, C.-G. Wahlstrom, W. Ubachs,
Isotope dependent predissociation in the C1Σ+, v=0 and v=1 states of CO
Eur. Phys. J. D 15, 47-56 (2001).
[87] I. Velchev, W. Ubachs,
Higher-order stimulated Brillouin scattering with non-diffracting beams
Opt. Lett. 26, 530-532 (2001).
[86] G. Bazalgette Courreges-Lacoste, J.P. Sprengers, W. Ubachs, S. Stolte, H. Linnartz,
The A2Σ+-X2Π transition of CF starting from highly excited vibrational states
J. Mol. Spectr. 205, 341-343 (2001).
[85] H. Naus, W. Ubachs, P.F. Levelt, O.L. Polyansky, N.F. Zobov, J. Tennyson,
Cavity-Ring-Down spectroscopy on water vapour in the range 555-604 nm
J. Mol. Spectr. 205, 117-121 (2001).
[84] W. Ubachs,
Laboratory studies of Long-range Excited states of H2
in: Molecular Hydrogen in Space, eds. F. Combes and G. Pineau des Forets, Cambridge University Press, p 39-46 (2000).
[83] A. de Lange, E. Reinhold, W. Hogervorst, W. Ubachs,
g/u symmetry breaking in HD at the n=2 dissociation limit
Can. J. Phys. 78, 567-578 (2000).
[82] W. Ubachs, I. Velchev, P. Cacciani,
Predissociation in the E1Π, v=1 state of the six natural isotopomers of CO
J. Chem. Phys. 113, 547-560 (2000).
[81] E. Reinhold, W. Hogervorst, W. Ubachs,
Tunneling and decay dynamics of HH1Σg+ outer well states in hydrogen
J. Chem. Phys. 112, 10754-10760 (2000).
[80] S.C. Xu, R. van Dierendonck, W. Hogervorst, W. Ubachs,
A dense grid of reference iodine lines for optical frequency calibration in the range 595-655 nm
J. Mol. Spectr. 201, 256-266 (2000).
[79] W. van der Zande, W. Ubachs,
Comment on: First observation of the rotational constants for the homonuclear ion He2+
Phys. Rev. Lett. 84, 3212 (2000).
[78] W. Ubachs, I. Velchev, A. de Lange,
Predissociation in b1Πu, v (v=1,4,5,6) levels of N2
J. Chem. Phys. 112, 5611-5616 (2000).
[77] H. Naus, W. Ubachs,
Experimental verification of Rayleigh-scattering cross sections
Opt. Lett. 25, 347-349 (2000).
[76] A.N. Maurellis, R. Lang, W. van der Zande, I. Aben, W. Ubachs,
Precipitable water column retrieval from GOME data
Geoph. Res. Lett. 27, 903-906 (2000).
[75] I. Velchev, D. Neshev, W. Hogervorst, W. Ubachs,
Pulse compression to the sub-phonon lifetime region by half-cycle gain in transient stimulated Brillouin scattering
IEEE J. of Quant. Electr. 35, 1812-1816 (1999).
[74] C.R. Scheper, C.A. de Lange, E. Reinhold, A. de Lange, W. Ubachs,
Dissociation of H2 in the energy region at the H(n=1) + H(n=3) dissociation threshold after (1+1') resonance-enhanced two photon ionization via the B1Σu+ state
Chem. Phys. Lett. 312, 131-138 (1999).
[73] A. de Lange, W. Ubachs,
Observation of the y1Πg-c4' 1Σu+ and k1Πg-c4' 1Σu+ systems of N2
Chem. Phys. Lett. 310, 471 (1999).
[72] E. Reinhold, W. Hogervorst, W. Ubachs, L. Wolniewicz,
Experimental and theoretical investigation of the HH1Σg+ state in H2, D2 and HD and the B"B1Σu+ state in HD
Phys. Rev. A60, 1258 (1999).
[71] I. Velchev, W. Hogervorst, W. Ubachs,
Precision VUV spectroscopy of Argon I at 105 nm
J. Phys. B 17, L511 (1999).
[70] R. Teule, S. Stolte, W. Ubachs,
Collision-induced E(0g+)-D(0u+) state-to-state energy transfer in I2
Laser Chemistry 18, 111-128 (1999).
[69] H. Naus, W. Ubachs,
Visible absorption bands of the (O2)2-collision complex at pressures below 760 Torr
Appl. Optics 38, 3423-3428 (1999).
[68] H. Naus, K. Navaian, W. Ubachs,
The γ-band of 16O2, 16O17O, 17O2 and 18O2
Spectrochimica Acta 55, 1255 (1999).
[67] D. Neshev, I. Velchev, W. Majewski, W. Hogervorst, W. Ubachs,
SBS Pulse compression to 200 ps in a compact single-cell setup
Appl. Phys. B68, 671 (1999).
[66] H. Naus, W. Ubachs,
The b1Σg+ - X3Σg- (3,0) band of 16O2 and 18O2
J. Mol. Spectr. 193, 442-445 (1999).
[65] E. Reinhold, A. de Lange, W. Hogervorst, and W. Ubachs,
Observation of the I' 1Πg outer well state in H2 and D2
J. Chem. Phys. 109, 9772 (1998).
[64] E. Reinhold, W. Hogervorst, and W. Ubachs,
Complete g-u symmetry breaking in highly excited valence states of the HD molecule
Chem. Phys. Lett. 296, 411 (1998).
[63] H. Naus, S.J. van der Wiel, W. Ubachs,
Cavity-ring-down spectroscopy on the b1Σg+ - X3Σg- (1,0) band of oxygen isotopomers
J. Mol. Spectr. 192, 162-168 (1998).
[62] P.C. Hinnen, S. Stolte, W. Hogervorst, W. Ubachs,
XUV-laser spectrometer for direct absorption measurements; application to CO in the wavelength range 96-97 nm
J. Opt. Soc. Am. B15, 2620-2625 (1998).
[61] P.P. Sorokin, J.H. Glownia, W. Ubachs,
Current Status of the H2 diffuse interstellar bands theory
Faraday Discussion 109, 137-163 (1998).
[60] W. Hogervorst, K.S.E. Eikema, E. Reinhold, W. Ubachs,
Precision XUV-laser spectroscopy of atomic and molecular two-electron systems
Nuclear Physics, A631, 353 (1998).
[59] P. Cacciani, W. Ubachs, P.C. Hinnen, C. Lynga, A. L'Huillier, C.-G. Wahlstrom,
Lifetime measurements of the E1Π, v=0 and v=1 states of 12C16O, 13C16O and 13C18O
Astroph. J. Lett. 499, L223 (1998).
[58] S. Schiemann, W. Hogervorst, W. Ubachs,
Fourier-transform-limited laser pulses tunable in wavelength and pulse duration (400-2000 ps)
IEEE J. of Quantum Electr. 34, 407-412 (1998).
[57] I. Velchev, R. van Dierendonck, W. Hogervorst, W. Ubachs,
A dense grid of reference iodine lines for optical frequency calibration in the range 571-596 nm
J. Mol. Spectr. 187, 21-27 (1998).
[56] E.J. Brinksma, Y.J. Meijer, I.S. McDermid, R.P. Cageao, J.B. Bergwerff, D.P.J. Swart, W. Ubachs, W.A. Matthews, W. Hogervorst, J.W. Hovenier,
First LIDAR observations of mesospheric hydroxyl
Geoph. Res. Lett. 25, 51-54 (1998). Correction: Geoph. Res. Lett. 25, 521 (1998).
[55] H. Naus, A. de Lange, W. Ubachs,
b1Σg+ - X3Σg- (0,0) band of oxygen isotopomers in relation to tests of the symmetrization postulate in 16O2
Phys. Rev. A56, 4755 (1997).
[54] W. Ubachs, K.S.E. Eikema, W. Hogervorst, P.C. Cacciani,
Narrow-band tunable extreme ultaviolet laser source for lifetime measurements and precision spectroscopy
J. Opt. Soc. Am. B14, 2469 (1997).
[53] E. Reinhold, W. Hogervorst, W. Ubachs,
Observation of a highly excited long-lived valence state in H2
Phys. Rev. Lett. 78, 2543 (1997).
[52] S. Schiemann, W. Ubachs, W. Hogervorst,
Efficient temporal compression of coherent nano second pulses in a compact generator-amplifier setup
IEEE J. Quant. Electr. 33, 358 (1997).
[51] K.S.E. Eikema, W. Ubachs, W. Vassen, W. Hogervorst,
Lamb shift measurement in the 1 1S ground state of helium
Phys. Rev. A55, 1866 (1997).
[50] W. Ubachs,
Predissociative decay of the c'4 1Σu+, v=0 state of molecular nitrogen
Chem. Phys. Lett. 268, 201 (1997).
[49] W. Ubachs, P.C. Hinnen, E. Reinhold,
Observation of inter-Rydberg transitions in H2 coinciding with Diffuse Interstellar Bands
Astrophys. J. Lett. 476, L93 (1997).
[48] K.S.E. Eikema, W. Ubachs, W. Vassen, W. Hogervorst,
Precision measurements in helium at 58 nm: Ground state Lamb shift and the 1 1S - 2 1P transition isotope shift
Phys. Rev. Lett. 76, 1216 (1996).
[47] R. van Leeuwen, W. Ubachs, P. Camus, W. Hogervorst,
Electron correlation in three-body Coulomb states of barium
Phys. Rev. A54, R17 (1996).
[46] P.C. Hinnen, W. Ubachs
Further tests concerning the hypothesis of H2 as the carrier of the diffuse interstellar bands
Chem. Phys. Lett. 254, 32 (1996).
[45] E. Reinhold, W. Hogervorst, W. Ubachs,
High resolution laser spectroscopy of H2 at 86-90 nm
J. Mol. Spectr. 180, 156 (1996).
[44] R. van Leeuwen, M. Aymar, W. Ubachs, W. Hogervorst,
Channel mixing in 4fng autoionizing series of barium
J. Phys. B29, 1007 (1996).
[43] P.C. Hinnen, W. Ubachs
On the hypothesis of H2 as the carrier of the diffuse interstellar bands
Chem. Phys. Lett. 240, 351-356 (1995).
[42] P.C. Hinnen, S.E. Werners, W. Hogervorst, S. Stolte, W. Ubachs,
XUV laser spectroscopy of HD at 92-98 nm
Phys. Rev. A52, 4425 (1995).
[41] W. Ubachs, P.C. Hinnen, P. Hansen, S. Stolte, W. Hogervorst, P. Cacciani,
Laser spectroscopic studies of the C1Σ+, v=0 and v=1 states of CO
J. Mol. Spectr. 174, 388-396 (1995).
[40] P. Cacciani, W. Hogervorst, W. Ubachs,
Accidental predissociation phenomena in the E1Π, v=0 and v=1 states of 12C16O and 13C16O
J. Chem. Phys. 102, 8308 (1995).
[39] R. van Leeuwen, W. Ubachs, W. Hogervorst, M. Aymar, E. Luc-Koenig,
Interference effects in the autoionization of 4f7h and 6dni states of barium
Phys. Rev. A52, 4567 (1995).
[38] E. Luc-Koenig, M. Aymar, R. van Leeuwen, W. Ubachs, W. Hogervorst,
Polarization effects in autoionization processes: the 5d5g states in barium
Phys. Rev. A52, 208 (1995).
[37] W. Ubachs,
Resonant Ionization spectroscopy in the XUV spectral region
AIP Conf. Proc. 329, 283-288 (1995).
[36] K.S.E. Eikema, W. Ubachs, W. Hogervorst,
Isotope shift in the neon ground state by XUV-laser spectroscopy at 74 nm
Phys. Rev. A49, 803 (1994).
[35] K.S.E. Eikema, W. Hogervorst, W. Ubachs,
Predissociation in carbon monoxide: dependence on rotational state, parity and isotope
Chem. Phys. 181, 217 (1994).
[34] W. Ubachs, K.S.E. Eikema, P.F. Levelt, W. Hogervorst, M. Drabbels, W.L. Meerts, J.J. ter Meulen,
Accurate determination of predissociation rates and transition frequencies for Carbon Monoxide
Astrophys. J. Lett. 427, L55 (1994).
[33] K.S.E. Eikema, W. Hogervorst, W. Ubachs,
On the determination of a heterogeneous vs a homogeneous perturbation in a diatomic molecule: the K1Σ+, v=0 state of 13C18O
J. Mol. Spectr. 163, 19-26 (1994).
[32] P.C. Hinnen, W. Hogervorst, S. Stolte, W. Ubachs,
Sub-Doppler laser spectroscopy of H2 and D2 in the range 91-98 nm
Can. J. Phys. 72, 1032-1042 (1994).
[31] P.C. Hinnen, W. Hogervorst, S. Stolte, W. Ubachs,
High-resolution laser spectroscopy on H2 at 97-98 nm
Appl. Phys. B 59, 307-310 (1994).
[30] R. van Leeuwen, W. Ubachs, W. Hogervorst,
Autoionization of low-lying 5dng states in barium
J. of Phys. B 27, 3891 (1994).
[29] K.S.E. Eikema, W. Ubachs, W. Vassen, W. Hogervorst,
First laser excitation of the 4He 1 1S - 2 1P resonance line at 58 nm
Phys. Rev. Lett. 71, 1690 (1993).
[28] I. Aben, W. Ubachs, G. van der Zwan, W. Hogervorst,
Linewidth effects in resonant CARS processes
Opt. Comm. 95, 97 (1993).
[27] I. Aben, W. Ubachs, G. van der Zwan, W. Hogervorst,
Theory of rotational linestrengths for resonant four-wave-mixing processes in gaseous media with application to CARS
Chem. Phys. 169, 113 (1993).
[26] I. Aben, W. Ubachs, G. van der Zwan, W. Hogervorst,
Resonance CARS in Br2
Chem. Phys. Lett. 198, 149 (1993).
[25] W. Ubachs, K.S.E. Eikema, W. Hogervorst,
Narrowband extreme ultraviolet radiation tunable in the range 90.5-95 nm: application to spectroscopy of N2
Appl. Phys. B57, 411-416 (1993).
[24] W. Ubachs, I. Aben, J.B. Milan, G.J. Somsen, A.G. Stuiver, W. Hogervorst,
Radiative and collisional relaxation of a single rovibrational quantum state of I2: E(0+g), n=8, J=56
Chem. Phys. 174, 285 (1993).
[23] P.F. Levelt, K.S.E. Eikema, S. Stolte, W. Hogervorst, W. Ubachs,
XUV-laser excitation of molecular fluorine
Chem. Phys. Lett. 210, 307 (1993).
[22] G. Kuik, R. van Leeuwen, R. de Graaf, W. Vassen, W. Ubachs, W. Hogervorst
Laser Spectroscopy of doubly-excited states in barium
AIP Conf. Proc. 275, 353-362 (1993).
[21] P.F. Levelt, W. Ubachs,
XUV-laser spectroscopy on the c4' 1Σu+, v=0 and c3 1Πu, v=0 Rydberg states of N2
Chem. Phys. 163, 263 (1992).
[20] P.F. Levelt, W. Ubachs, W. Hogervorst,
Extreme ultraviolet laser spectroscopy on CO in the 91-100 nm range
J. Chem. Phys. 97, 7160 (1992).
[19] P.F. Levelt, W. Ubachs, W. Hogervorst,
XUV laser spectroscopy on CO: isotope selective predissociation rates
J. Phys. II France 2, 801-812 (1992).
[18] R.J. de Graaff, W. Ubachs, W. Hogervorst,
4fnf doubly-excited autoionizing series in barium
Phys. Rev. A45, 166 (1992).
[17] I. Aben, W. Ubachs, G. van der Zwan, W. Hogervorst,
Polarization effects in resonant four-wave mixing processes
Mol. Phys. 76, 591 (1992).
[16] I. Aben, W. Ubachs, G. van der Zwan, W. Hogervorst,
Multiple resonance enhanced four-wave mixing processes in I2
Phys. Rev. A76, 5881 (1991).
[15] M. Abutaleb, R.J. de Graaff, W. Ubachs, W. Hogervorst,
The 5dnp and 5dnf J=1 autoionizing series of Ba in one-photon laser excitation from the 6s2 1S0 ground state
J. Phys. B24, 3565-3573 (1991).
[14] M. Abutaleb, R.J. de Graaff, W. Ubachs, W. Hogervorst,
6p1/2,3/2nf J=1-5 autoionizing series of Barium
Phys. Rev. A44, 4187 (1991).
[13] R.J. de Graaff, W. Ubachs, W. Hogervorst, and M. Abutaleb,
Narrow 6p1/2,3/2np J=1 autoionizing Rydberg series in Barium and their interaction with 6p3/2nf states
Phys. Rev. A42, 5473 (1990).
[12] W. Ubachs and J.J. ter Meulen,
Comment on: Lifetime of the A2Σ+, v=0 state of SH
J. Chem. Phys. 92, 2121-2122 (1990).
[11] I. Aben, P. Levelt, W. Ubachs, W. Hogervorst,
Resonance CARS in Br2 molecules and Br atoms
Inst. Phys. Conf. Series 114, 193-194 (1990).
[10] W. Ubachs, L.M. Tashiro, and R.N. Zare,
Study of the N2 b1Πu state via 1+1 multiphoton ionization
Chem. Phys. 130, 1 (1989).
[9] L.M. Tashiro, W. Ubachs, and R.N. Zare,
The HF and DF B1Σ+-X1Σ+ and C1Π-X1Σ+ band systems studied by 1 XUV +1 UV resonance enhanced multiphoton ionization
J. Mol. Spectr. 138, 89 (1989).
[8] G. Meijer, W. Ubachs, J.J. ter Meulen, and A. Dymanus,
High resolution Lamb-dip spectroscopy on OD and SiCl in a molecular beam
Chem. Phys. Lett. 139, 603 (1987).
[7] W. Ubachs, G. Meijer, J.J. ter Meulen, and A. Dymanus,
High resolution laser spectroscopy on the c1Π - a1Δ transition in NH
J. Mol. Spectr. 115, 88 (1986).
[6] W. Ubachs, G. Meijer, J.J. ter Meulen, and A. Dymanus,
Hyperfine structure and lifetime of the C2Σ+ state of CH
J. Chem. Phys. 84, 3032-3041 (1986).
[5] W. Ubachs, W. van Herpen, J.J. ter Meulen, and A. Dymanus,
Hyperfine structure and Λ-doubling in the A2Δ state of CH: observation of an internal hyperfine perturbation
J. Chem. Phys. 84, 6575-6580 (1986).
[4] J.J. ter Meulen, W. Ubachs, and A. Dymanus,
Observation of ρ-doublet transitions in OH (A2Σ+) by UV-microwave double resonance in a molecular beam
Chem. Phys. Lett. 129, 533 (1986).
[3] W. Ubachs, A.P.J. van Deursen, A.R. de Vroomen, and A. Arko,
Fermi surface measurements of UPd3
Solid. State Comm. 60, 7 (1986).
[2] W. Ubachs, J.J. ter Meulen, and A. Dymanus,
High resolution laser spectroscopy on the A3Π - X3Σ- transition of NH
Can. J. Phys. 62, 1374-1391 (1984).
[1] W. Ubachs, J.J. ter Meulen, and A. Dymanus,
High resolution molecular beam spectroscopy on the A2Σ+, v=0 state of SH
Chem. Phys. Lett. 101, 1 (1983).