INFRARED SPECTRA OF THE $v_{1}$ AND $v_{4}$ BANDS OF $CH_{2}D^{+}$ AND THE $v_{1}$ BAND OF $CHD_{2}^{+}$
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Date
1992
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Journal ISSN
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Publisher
Ohio State University
Abstract
The methy cation $CH_{3}^{+}$ is a most fundamental and stable carbocation and is expected to exist abundantly in various astronomical sources. Its radioastronomical detection is hampered by its symmetry and zero dipole moment. In order to save this situation, we have attempted the spectroscopy of its deuterated species which have effective dipole moments of 0.329 and 0.310 debye. The $v_{1}$ and $v_{4}$ bands of $CH_{2}$ $D^ {+1,2}$ and the $v_{1}$ band of $CHD_{2}^{+2}$ have been observed and analyzed. Both species were formed concurrently in a gas mixture of $CD_{4}$:$CH_{4}$:$H_{2}$:He::120:10:100:7000 m Torr discharged al 6 kHz with $\sim$150 mA in a multiple-inlet multiple-outlet, liquid-nitrogen-cooled cell. Their infrared vibration-rotation spectra were recorded with a difference-frequency spectrometer and detected by velocity modulation with unidirectional multipassing and noise subtraction of the probing infrared radiation. The transitions of each band were fitted separately to Watson A-reduced Hamiltonian to determine the rotational and quartic centrifugal distortion constants. The determined band origins (in $cm^{-1}$ are $v_{1} = 3004.7650(5)$ and $v_{4} = 3105.8406(6)$ for $CH_{2}$$D^{+}$ and $v_{1} = 3056.1694(8)$ for $CHD_{2}^{+}$. Their inertial defects $\Delta$, centrifugal distortion constants, and rotational transitions have been calculated.
Description
1. M. R\""{o}sslein, M.-F. Jagod, C. M. Gabrys, and T. Oka, Astrophys. J. 382 , L51 (1991). 2. M.-F Jagod. M. R\""{o}sslein. C. M. Gabrys, and T, Oka, J. Mol. Spectrosc. 153 (1992), in press.
Author Institution: Department of Chemistry and Department of Astronomy and Astrophysics, The University of Chicago; Physikalisch-Chemisches Institut der Universit\""{a}t Z\""{u}rich CH-8057, Z\""{u}rich, Switzerland
Author Institution: Department of Chemistry and Department of Astronomy and Astrophysics, The University of Chicago; Physikalisch-Chemisches Institut der Universit\""{a}t Z\""{u}rich CH-8057, Z\""{u}rich, Switzerland