Overtone spectroscopy of molecular complexes containing small polyatomic molecules

Abstract

The literature on the high-resolution spectroscopic investigation of molecular complexes containing small polyatomic species excited in their vibrational overtones is reviewed. They turn out to be complexes containing acetylene, ammonia and water, mainly excited in their 2CH, 2NH and 2OH vibrations, respectively. The majority of results published on these systems was obtained using an instrumental set-up based on cw-cavity ring-down spectroscopy, built in the ‘Laboratoire de Chimie quantique et Photophysique’ at the ‘Université libre de Bruxelles’ (CQP/ULB) and named FANTASIO+, which is described. It allowed retrieving upper state vibrational predissociation lifetimes, which are highlighted together with more results. The sequence of experiments at CQP/ULB prior and along the line of those supporting the investigation of molecular complexes is briefly illustrated.

Keywords:

• van der Waals molecule
• molecular complex
• high-resolution overtone spectroscopy
• cavity ring-down spectroscopy
• vibrational predissociation
• supersonic jet cooling
• acetylene dimer
• ammonia dimer
• water dimer
• clusters
• ab initio calculations

Acknowledgments

We are indebted to a number of colleagues including Drs/Profs. R. Georges (Rennes), D. Hurtmans (ULB), S. Kassi (Grenoble) and P. Macko (Ispra) for their contribution to instrumental developments at CQP/ULB, and more. We thank Prof. J. Liévin (ULB), Dr J. Vander Auwera (ULB) and all co-authors of FANTASIO+ papers for their help. We also thank Mrs A. Rizopoulos and Mr P. Van Poucke (ULB) for technical support. The Wiener Anspach foundation supported recent activities around FANTASIO+ and INNOVIRIS and FRS-FNRS-FRIA provided salaries for two of the co-authors.