HIGH RESOLUTION FOURIER TRANSFORM EMISSION SPECTROSCOPY OF THE $\widetilde{A}^{2}\Pi-\widetilde{X}^{2}\Pi$ TRANSITION OF THE $OCS^{+}$ ION
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Date
2004
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Publisher
Ohio State University
Abstract
The $OCS^{+}$ ion was produced by Penning ionization of OCS with metastable $He^{\ast}$, and UV emission in the 370 --- 500 nm region was measured by Fourier transform spectrometer. The $\widetilde{A}^{2}\Pi-\widetilde{X}^{2}\Pi$ electronic transition has been reported in the 300 --- 500 nm region, but only the emission bands from the vibrational ground state of the $\widetilde{A}\Pi^{2}$ state were observed because of the predissociation in the $\widetilde{A}^{2}\Pi$ $state^{a}$. High resolution study of the 0-0 band has been reported for both the $\Omega = 3/2$ and $\Omega = 1/2$ spin $states ^{b,c}$. In the present study, seven rotationally resolved bands were observed in the 370 --- 500 nm region and assigned to the CO stretch $(\nu^{\prime\prime}_{3})$ progression: $\widetilde{A}^{2}\Pi_{3/2}(000)-\widetilde{X}^{2}\Pi_{3/2}(00v)(v=2-5)$ and $\widetilde{A}^{2}\Pi_{1/2}(000)-\widetilde{X}^{2}\Pi_{1/2}(00v)(v=3-4)$. The observed lines of the $\Omega = 1/2$ substate were split into the two components due to the A-type doubling. The spectra for $\Omega = 3/2$ and $\Omega = 1/2$ were analysed separately to obtain molecular constants for each spin state. Band origins, vibrational frequencies, rotational constants, vibrational-rotational constants for both spin substates and A-type doubling constant for the $\Omega = 1/2$ substate were determined by a least squares fitting. Rotational constants in the vibrational ground state were determined for both spin states. The spin-orbit interaction constants derived from these rotational constants, $A^{\prime} = -125.0 cm^{-1}$ and $A^{\prime\prime} = -383.8 cm^{-1}$, are consistent with those derived from the photodissociation $study ^{d}$.
Description
$^{a}$D. L. Judge and L. C. Lee, Int. J. Mass Spectrom. Ion Phys., 17, 329, (1975) $^{b}$M. Oschner, M. Tsuji, and J. P. Maier, Chem. Phys. Lett., 115, 373, (1985) $^{c}$R. Weinkauf and U. Boesl, J. Chem. Phys., 101, 8482, (1994) $^{d}$R. Kakoschke, U. Boesl, J. Hermann and E. W. Schlag, Chem. Phys. Lett., 119, 467, (1985)
Author Institution: Department of Chemistry, Faculty of Science, Kyushu University 33
Author Institution: Department of Chemistry, Faculty of Science, Kyushu University 33