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MO: Fachverband Molekülphysik
MO 30: Molecular Spectroscopy and Theoretical Approaches
MO 30.1: Talk
Friday, March 14, 2025, 14:30–14:45, HS XVI
High-resolution rovibrational spectroscopy of H5+ — •Samuel Marlton, Philipp Schmid, Thomas Salomon, Janos Sarka, Divita Gupta, Oskar Asvany, and Stephan Schlemmer — University of Cologne, Cologne, Germany
H5+ is an extremely floppy molecular ion that is so complex that it pushes the limits of foundational concepts in spectroscopy and molecular physics such as molecular structure, normal modes of vibration, typical group theoretical treatments, and the separation of vibrational and rotational degrees of freedom. Using leak-out spectroscopy (LOS) it is finally possible to measure infrared transitions of H5+ with high resolution.[1] In this experiment, H5+ ions are stored in a cryogenic (20 K) 22-pole ion trap and irradiated with an infrared laser. Photoexcited ions collide with neutral He gas atoms to transfer the vibrational internal energy of the ion into kinetic energy, giving the ion sufficient kinetic energy to leak out of the trap and be detected. The LOS spectrum is constructed by measuring the leak-out ion yield as a function of laser frequency. We employ LOS to measure the H5+ vibrational band centred at 940 cm−1 (a combination band exciting the central proton hop and outer hydrogen separation), which is a promising step to understanding extremely floppy molecules.
[1] Schmid et al., 2022, J. Phys. Chem. A., 126(43), pp.8111-8117.
Keywords: ions; rovibration; leak-out spectroscopy; symmetry; tunneling