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Title:Assigning States In The Jahn-teller Coupled Infrared Spectra Of Ch3o And Cd3o
Author(s):Johnson, Britta
Contributor(s):Sibert, Edwin
Subject(s):Matrix isolation (and droplets)
Abstract:\hspace*{1cm} The ground $\tilde{X}^2E$ vibrations of the methoxy radical have intrigued both experimentalists and theorists alike due to the presence of a conical intersection at the C$_{3v}$ molecular geometry. This conical intersection causes methoxy's vibrational spectrum to be strongly influenced by Jahn-Teller coupling, this leading to large amplitude vibrations and extensive mixing of the two lowest electronic states. This coupling combined with spin-orbit and Fermi couplings greatly complicates the assignments of states. In this talk we describe our efforts to assign the states of both CH$_3$O and CD$_3$O. \hspace*{1cm} Using the potential energy force field and calculated spectra of Nagesh and Sibert$^1$ as a starting point, vibrational mixing is considered using various zero-order representations. When the zero-order states are the diabatic normal mode states, there is sufficient mode mixing that the normal mode quantum numbers are no longer good labels. The mixing of the zero-order states can be reduced by including additional terms in the zero-order Hamiltonian, $H^o$. We consider the choice of including the first order Jahn-Teller coupling between one of the three degenerate normal modes. As the rocking motion has the largest Jahn-Teller coupling, this is the coupling that is included in $H^o$. Although the normal mode quantum numbers of the rocking basis functions are no longer good quantum numbers, due to the Jahn-Teller induced vibronic mixing, the zero-order states can be labeled with the linear Jahn-Teller quantum numbers.$^2$ This work extends these ideas by considering an $H^o$ that includes linear Jahn-Teller coupling between {\it two} sets of degenerate vibrations. Plots of the resulting zero-order states are presented, and the spectral transitions recently observed$^{3}$ for both CH$_3$O and CD$_3$O in a $p$-H$_2$ matrix are assigned using these basis functions. The extent of state-mixing found for the full Hamiltonian $H$ for various choices of $H^o$ is illustrated via the use of correlation diagrams obtained by plotting the eigenvalues of $H^o + \delta (H-H^o)$ as a function of $\delta$ where $\delta$ varies from zero to one. \begin{list}{}{}\item[$^1$] Nagesh, J.; Sibert, E.~L. {\em J. Phys. Chem. A} {\bf 2012}, {\em 116}, 3846--3855. \item[$^2$] Barckholtz, T.~A.; Miller, T.~A. {\em Int. Revs. in Phys. Chem.} {\bf 1998}, {\em 17}, 435--524. \item[$^3$] Yu-Fang Lee, Wei-Te Chou, and Yuan-Pern Lee (private communication). \end{list}
Issue Date:2014-06-19
Publisher:International Symposium on Molecular Spectroscopy
Citation Info:Johnson, B.; Sibert, E. ASSIGNING STATES IN THE JAHN-TELLER COUPLED INFRARED SPECTRA OF CH3O AND CD3O. Proceedings of the International Symposium on Molecular Spectroscopy, Urbana, IL, June 16-21, 2014. DOI: 10.15278/isms.2014.RI04
Rights Information:Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License.
Date Available in IDEALS:2014-09-17

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