LEAK-OUT SPECTROSCOPY OF PROTONATED WATER DIMER I: RO-VIBRATIONAL SPECTRA

Salomon, Thomas

Permalink

https://hdl.handle.net/2142/122359 Copy

Description

Title

LEAK-OUT SPECTROSCOPY OF PROTONATED WATER DIMER I: RO-VIBRATIONAL SPECTRA

Author(s)

Salomon, Thomas

Contributor(s)

• Schlemmer, Stephan
• Asvany, Oskar

Issue Date

2023-06-21

Keyword(s)

Mini-symposium: Spectroscopy with Cryogenic Ion Traps

Abstract

The symmetric O-H stretching band of the protonated water dimer is re-investigated at high spectral resolution applying the novel action spectroscopic technique leak-out spectroscopy (LOS) in the 22-pole ion trap experiment COLtrap operated at 4 K. Ro-vibrational transitions of Helium buffer gas cooled H₅O₂⁺ are excited using a narrow linewidth optical parametric oscillator prior to collisions with Neon as a second buffer gas. In doing so, part of the internal energy of the previously excited cation is transferred into kinetic energy (V-T-transfer) allowing it to surpass the electrostatic potential at the exit electrode of the 22-pole trap. The amount of cations exiting the trap time during the total trap time is monitored using a quadrupole mass-filter and a Daly-type ion detector. The resulting rotationally resolved spectrum is intrinsically background-free because the parent ground state ions are trapped without loss. The line intensities measured by LOS turn out to be closely related to the line intensities of conventional absorption spectroscopy. The new and extensive spectra are compared to previously presented high-resolution data obtained using a two-color-photodissociation scheme. Basically, the previously observed spectral complexity is confirmed by the novel action spectroscopic technique. The single-color leak-out spectra are more reliable in their actual line intensities as any impact on the dissociation efficiency originating from a variation of the optical overlap between two lasers experiments or power fluctuations are avoided. This improvement further simplifies the identification of Q-branches which can be nicely spotted in the high S/N spectra. Based on the multiplicity of these Q-branches and their separation, the tunneling motions at play for this molecular complex can be deciphered. Our findings challenge the current view on the structure and dynamics of the protonated water dimer.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Handle URL

https://hdl.handle.net/2142/122359

DOI

https://doi.org/10.15278/isms.2023.6906

Owning Collections