Conformer specific methyl internal rotation and observation of photodissociation dynamics: Is methyl internal rotation coupled with torsional vibration?

Lee, Heesung

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https://hdl.handle.net/2142/100624

Description

Title

Conformer specific methyl internal rotation and observation of photodissociation dynamics: Is methyl internal rotation coupled with torsional vibration?

Author(s)

Lee, Heesung

Contributor(s)

Kim, Sang Kyu
Kim, Junggil
Lim, Jean Sun
Kim, So-Yeon

Issue Date

2018-06-20

Keyword(s)

Structure determination

Abstract

The spectroscopic peak assignment gives barrier height of internal rotation as well as minimum angle displacement between S1 and S0 electronic states. The most well-known type is methyl internal rotation because most organic molecules have it. Conventional way to assign the spectra uses 1D hindered rigid rotor model. The model system is thioanisole because it engendered mode specific nonadiabatic photofragment in previous experimenta . Resonance enhanced multiphoton ionization (REMPI) followed by velocity-map imaging (VMI) made us be possible to assign the methyl internal rotation peaks and to see the dynamics of the photodissociation. Conformers were selectively sampled using different carrier gases in supersonic jet-expansion and their electronic transitions were confirmed by UV-UV hole-burning spectroscopy equipped with Stark-Deflector. In this presentation, trans meta-methylthioanisole (mMTA) manifests active progressions of methyl internal rotation (0a1, 1e, 2e, 3a1, 4e, 5e, 6a1), whereas a few of them (0a1, 1e, 3a1) for cis mMTA are tangible. For cis mMTA, the rotor progressions are combined with the torsional vibration. In case of trans ortho-methylthioanisole (oMTA), not only active combinations of methyl internal rotation and torsional vibration but also couplings of them seem to be exist in S1-S0 transitionsb . VMI studies imply two distinguished photodissociation dynamics of oMTA and mMTA, respectively. The detailed comparison of them is to be presented.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100624

DOI

10.15278/isms.2018.WK12

Copyright and License Information

Copyright 2018 Heesung Lee

Owning Collections

Abstracts & Presentations - 2018 International Symposium on Molecular Spectroscopy PRIMARY