JET-COOLED LASER-INDUCED FLUORESCENCE SPECTROSCOPY OF T-BUTOXY

Liu, Jinjun

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https://hdl.handle.net/2142/79089 Copy

Description

Title

JET-COOLED LASER-INDUCED FLUORESCENCE SPECTROSCOPY OF T-BUTOXY

Author(s)

Liu, Jinjun

Contributor(s)

• Miller, Terry A.
• Stanton, John F.
• Cheng, Lan
• Reilly, Neil J

Issue Date

26-Jun-15

Keyword(s)

Atmospheric science

Abstract

The vibrational structures of the $tilde A ^2$A$_1$ and $tilde X ^2$E states of t-butoxy were obtained in jet-cooled laser-induced fluorescence (LIF) and dispersed fluorescence (DF) spectroscopic measurements. The observed transitions are assigned based on vibrational frequencies calculated using Complete Active Space Self-Consistent Field (CASSCF) method and the predicted Franck-Condon factors. The spin-orbit (SO) splitting was measured to be 35(5) cm$^{-1}$ for the lowest vibrational level of the ground ($tilde X ^2$E) state and increases with increasing vibrational quantum number of the CO stretch mode. Vibronic analysis of the DF spectra suggests that Jahn-Teller (JT)-active modes of the ground-state t-butoxy radical are similar to those of methoxy and would be the same if methyl groups were replaced by hydrogen atoms. Coupled-cluster calculations show that electron delocalization, introduced by the substitution of hydrogens with methyl groups, reduces the electronic contribution of the SO splittings by only around ten percent, and a calculation on the vibronic levels based on quasidiabatic model Hamiltonian clearly attributes the relatively small SO splitting of the $tilde X ^2$E state of t-butoxy mainly to stronger reduction of orbital angular momentum by the JT-active modes when compared to methoxy. The rotational and fine structure of the LIF transition to the first CO stretch overtone level of the $tilde A^2$A$_1$ state has been simulated using a spectroscopic model first proposed for methoxy, yielding an accurate determination of the rotational constants of both $tilde A$ and $tilde X$ states.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

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http://hdl.handle.net/2142/79089

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