High-resolution laser spectroscopy of free radicals in nearly degenerate electronic states

Liu, Jinjun

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https://hdl.handle.net/2142/97127 Copy

Description

Title

High-resolution laser spectroscopy of free radicals in nearly degenerate electronic states

Author(s)

Liu, Jinjun

Issue Date

2017-06-19

Keyword(s)

Plenary

Abstract

Rovibronic structure of molecules in orbitally degenerate electronic states including Renner-Teller (RT) and Jahn-Teller (JT) active molecules has been extensively studied. Less is known about rotational structure of polyatomic molecules in emph{nearly} degenerate states, especially those with low (e.g., C$_s$) symmetry that are subject to the pseudo-Jahn-Teller (pJT) effect. In the case of free radicals, the unpaired electron further complicates energy levels by inducing spin-orbit (SO) and spin-rotation (SR) splittings. Asymmetric deuteration or methyl substitution of C$_{3v}$ free radicals such as CH$_3$O, CaCH$_3$, and CaOCH$_3$ lowers the molecular symmetry, lifts the vibronic degeneracy, and reduces the JT effect to the pJT effect. New spectroscopic models are required to reproduce the rovibronic structure and simulate the experimentally obtained spectra of pJT-active free radicals. It has been found that rotational and fine-structure analysis of spectra involving nearly degenerate states may aid in vibronic analysis and interpretation of emph{effective} molecular constants. Especially, SO and Coriolis interactions that couple the two states can be determined accurately from fitting the experimental spectra. Coupling between the two electronic states also affects the intensities of rotational and vibronic transitions. The study on free radicals in nearly degenerate states provides a promising avenue of research which may bridge the gap between symmetry-induced degenerate states and the Born-Oppenheimer (BO) limit of unperturbed electronic states._x000d_ _x000d_

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/97127

DOI

https://doi.org/10.15278/isms.2017.MA05

Copyright and License Information

Copyright 2017 Jinjun Liu

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