Coriolis perturbations to the 3ν4 level of the a state of formaldehyde

Park, Barratt

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https://hdl.handle.net/2142/96867 Copy

Description

Title

Coriolis perturbations to the 3ν4 level of the a state of formaldehyde

Author(s)

Park, Barratt

Contributor(s)

• Schaefer, Tim
• Meyer, Sven
• Krueger, Bastian C.

Issue Date

2017-06-20

Keyword(s)

Small molecules

Abstract

Formaldehyde is the smallest stable organic molecule containing the carbonyl functional group, and is commonly considered to be a prototype for the study of high-resolution spectroscopy of polyatomic molecules. The $a$-axis Coriolis interaction between the near-degenerate $nu_4$ and $nu_6$ (out-of-plane and in-plane wagging modes, respectively) of the ground electronic state has received extensive attention and is thoroughly understood. In the first excited singlet $mathrm{tilde{A}}$ $^1$A$_2$ electronic state, the analogous Coriolis interaction does not occur, because the $mathrm{tilde{A}}$ state suffers from a pseudo Jahn-Teller distortion, which causes a double-well potential energy structure in the $q_4'$ out-of-plane coordinate, and which dramatically reduces the effective $nu_4'$ frequency. The $nu_4'$ frequency is reduced by so great an extent in the $mathrm{tilde{A}}$ state that it is the $3nu_4'$ overtone which is near degenerate with $nu_6'$. In the current work, we report the precise $nu_6'$ fundamental frequency in the $mathrm{tilde{A}}$ state, and we determine the strength of the $a$-axis Coriolis interaction between $3nu_4'$ and $nu_6'$. We also provide a rotational analysis of the $nu_4'+nu_6'$ combination band, which interacts with $3nu_4'$ via an additional $c$-axis Coriolis perturbation, and which allows us to provide a complete deperturbed fit to the $3nu_4'$ rotational structure. Knowledge of the Coriolis interaction strengths among the lowest-lying levels in the $mathrm{tilde{A}}$ state will aid the interpretation of the spectroscopy and dynamics of many higher-lying band structures, which are perturbed by analogous interactions.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/96867

DOI

https://doi.org/10.15278/isms.2017.TK02

Copyright and License Information

Copyright 2017 Barratt Park

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