THE CYCLOPENTADIENYL RADICAL REVISITED: THE EFFECTS OF ASYMMETRIC DEUTERATION OF JAHN-TELLER MOLECULES
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Date
2012
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Ohio State University
Abstract
Asymmetric deuteration of Jahn-Teller active molecules partially lifts the vibronic degeneracy and hence provides a unique approach to understanding the Jahn-Teller effect. Previously, a spectroscopic model was proposed and used to simulate the spectra of the asymmetrically deuterated isotopomers of the methoxy radical. \textbf{105}, 529 (2007).} \textbf{135}, 094310 (2011)} The same model has been implemented and successfully simulated the previously reported high-resolution laser-induced fluorescence (LIF) spectra of the asymmetrically deuterated cyclopentadienyl radical (C$_5$H$_4$D and C$_5$HD$_4$). \textbf{98}, 2682 (1993).} A joint fitting of the transitions from both of the zero-point levels of the $\tilde X ^2$E$^{\prime\prime}_1$ ground electronic state, split by the asymmetric deuteration, to the $\tilde A ^2$A$^{\prime\prime}_2$ state yields one set of molecular constants for both levels, which, when combined with molecular constants of C$_5$H$_5$ and C$_5$D$_5$, can be used to determine the molecular geometry and magnitude of the Jahn-Teller distortion. The main goal of this new investigation is to resolve the discrepancy between the experimentally determined and the ab initio calculated Jahn-Teller distortion. \textbf{55}, 639 (1999).} In addition, a theoretic model is proposed to quantitatively reproduce the splitting of the zero-point level due to the asymmetric deuteration and zero-point energies for the Jahn-Teller distorted structures around the conical intersection.
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Author Institution: University of Louisville, Department of Chemistry, Louisville, KY 40292