SUB-MILLIMETER WAVE LINES OF THE LOWEST ROTATIONAL TRANSITION OF CH RADICAL
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Date
1999
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Ohio State University
Abstract
The lowest rotational transition of CH radical, $N = 1, J = 3/2, F_{1} \leftarrow N = 1, J = 1/2,F_{2}$, has been observed in 532.7 GHz and 536.8 GHz regions with a sub-millimeter wave spectrometer operated with a phase-locked backward-wave oscillator as a radiation source. The CH radical was generated in a DC glow discharge with a mixture of $CH_{4}(\sim 4mTorr)$ and $He(\sim 240 m Torr)$ and all the six hyperfine components were recorded, using frequency-discharge double modulation $technique^{a}$. These transitions had already been observed by using LMR $technique^{b}$ and the zero field transition frequencies were calculated with 1.5 MHz accuracy by Brown and $Evenson^{c}$. From our new direct observation, more accurate transition frequencies were determined with typically $\pm 30 kHz$ uncertainty. Astrophysically these accurate frequencies will be of great use for probing hydrocarbon chemistry in warmer and denser regions of molecular clouds.
Description
$^{a}$ T. Amano, paper RD05, 53rd International Symposium on Molecular Spectroscopy, Columbus, Ohio, USA, June, 1998 $^{b}$ J.T. Hougen et al, J. Mol. Spectrosc. 72, 463-483(1978) $^{c}$ J.M. Brown and K.M. Evenson, Astrophys. J.268, L51-L56(1983)
Author Institution: Institute for Astrophysics and Planetary Sciences, Ibaraki University
Author Institution: Institute for Astrophysics and Planetary Sciences, Ibaraki University