Coupling Of Torsion And Oh-stretching In <i>tert</i>-butyl Hydroperoxide And Its Radical Analog, Qooh

Huchmala, Rachel M.

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https://hdl.handle.net/2142/111178 Copy

Description

Title

Coupling Of Torsion And Oh-stretching In tert-butyl Hydroperoxide And Its Radical Analog, Qooh

Author(s)

Huchmala, Rachel M.

Contributor(s)

• McCoy, Anne B.
• Boyer, Mark A.

Issue Date

2021-06-23

Keyword(s)

Mini-symposium: Large Amplitude Motions

Abstract

Organic hydroperoxides and their radical products are important contributors to atmospheric chemistry, especially in atmospheric oxidation processes. Through understanding the vibrational spectroscopy of these compounds, we gain insights into their abundance in the atmosphere. The vibrational spectra of \textit{tert}-butyl Hydrogen Peroxide (TBHP) and its radical product QOOH have been studied both experimentally and theoretically.$^{1}$ Due to their floppy nature and many low frequency degrees of freedom, standard methods such as harmonic treatments and second order vibrational perturbation theory are insufficient to fully characterize vibrational spectra of these molecules. In this work, we introduce a reaction path model that is sufficient to explain the OH-stretching region of QOOH. Within this model, we perform an adiabatic separation of the OH-stretching and COOH-torsion modes and add a harmonic zero-point energy correction to account for the other vibrational degrees of freedom. In the process of developing this model, we first investigated the OH-stretching region of THBP.$^{2-3}$ Through this study, we discovered a strong contribution to the overall intensity in the v$_\textnormal{OH}$ + n$_\textnormal{tor}$ combination feature coming from the torsional dependence of the transition dipole moment. At low levels of vibrational excitation, the intensity of this feature reflects the torsion-dependence of the dipole function, while at higher levels of OH excitation (v$_\textnormal{OH}$ = 4 or 5) the intensity in this combination feature can be captured through a Franck-Condon treatment of the intensity. The transition from a mechanical to electrical origin to the intensity in this feature is discussed. Extension to QOOH will also be discussed. \noindent $^1$ M. D. Likar, J. E. Baggott, and F. F. Crim, \textit{J. Chem. Phys.} 90, 6266–6274 (1989). \noindent $^2$ A. S. Hansen, R. M. Huchmala, E. Vogt, M. Boyer, T. Bhagde, M. F. Vansco, C. V. Jensen, A. Kjaersgaard, H. G. Kjaergaard, A. B. McCoy, and M. I. Lester, \textit{J. Chem. Phys.} Submitted. 2021 \noindent $^3$ E. Vogt, R. M. Huchmala, C. V. Jensen, M. Boyer, Jens Wallberg, A. S. Hansen, A. Kjaersgaard, H. G. Kjaergaard, M. I. Lester, and A. B. McCoy, \textit{J. Chem. Phys.} Submitted. 2021

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Permalink

http://hdl.handle.net/2142/111178

DOI

10.15278/isms.2021.WA10

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