THE NEAR-INFRARED SPECTRUM OF CH$_2^+$
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Date
2005
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Publisher
Ohio State University
Abstract
The molecular ion CH$_2^+$ is of special theoretical interest because it is both quasi-linear and exhibits a strong Renner-Teller interaction between its ground and first-excited electronic states. At linearity, the ground state is a $^{2}\Pi_{u}$ state that splits into $\tilde{X}^{2}A_{1}$ and $\tilde{A}^{2}B_{2}$ states as the molecule bends. The $\tilde{A}$ state is linear, while the $\tilde{X}$ is quasi-linear with a barrier to linearity of only 1089 \wn. Thus, only the ground vibrational state is bound by the barrier to linearity. \vspace{2ex} The spectrum of CH$_2^+$ in the region 11,000--13,000 \wn\ has been recorded with our Ti:sapphire laser spectrometer. This spectrometer couples velocity modulation with heterodyne detection for near shot-noise-limited sensitivity. Since our initial letter on this spectrum,} \textbf{121}, 11527 (2004).} we have selectively rescanned portions of this spectrum with improved signal-to-noise. As a result, we have been able to assign the $\tilde{A}(0,3,0)^3 \leftarrow \tilde{X}(0,0,0)^2$ band and detect the $\tilde{X}(0,9,0)^2 \leftarrow \tilde{X}(0,0,0)^1$ band, whose assignment is in progress. A more detailed analysis of the entire spectrum, including spin splitting, is underway.
Description
{J. L. Gottfried and T. Oka, \textit{J. Chem. Phys.
Author Institution: Department of Chemistry, Department of Astronomy \& Astrophysics,; and the Enrico Fermi Institute, The University of Chicago, Chicago; IL, 60637, USA
Author Institution: Department of Chemistry, Department of Astronomy \& Astrophysics,; and the Enrico Fermi Institute, The University of Chicago, Chicago; IL, 60637, USA