Coulomb-crystallised molecular ions in traps: methods, applications, prospects

Abstract

Translationally cold, spatially localised molecular ions prepared by sympathetic cooling with laser-cooled atomic ions in ion traps have recently found a wide range of applications in both chemistry and physics. The very low temperatures of the ions (down to millikelvins), their tight localisation in the trap and the ability to control and manipulate single isolated molecules on the quantum level offer intriguing possibilities for new experiments in the realms of cold chemistry, precision molecular spectroscopy, mass spectrometry and quantum technology. The present article gives an overview of the basic experimental methods, current topics and recent developments in this field.

Keywords:

• Coulomb crystals
• molecular ions
• ion traps
• sympathetic cooling
• cold molecules
• cold chemistry
• precision spectroscopy

Acknowledgements

Financial support is acknowledged from the University of Basel, the COST Action ‘Ion Traps for Tomorrow's Applications’ and the Swiss National Science Foundation through the National Centre of Competence in Research ‘Quantum Science and Technology’ as well as grant nr. PP0022_118921.

Notes

Notes

1. Note that the q _u factor in Equation (2) differs by a factor of 2 from other sources in the literature because of a differing RF voltage configuration applied to the trap 13,18 or a different definition of the RF amplitude 11.

2. The need for only one cooling laser beam for trapped ions is actually also true for a perfect 3D harmonic potential provided the laser beam is not collinear with any main trap axis. This requirement can always be achieved as long as the trapping potential is not isotropic.