10min:

D. T. HALFEN, L. M. ZIURYS, University of Arizona, Steward Observatory, Department of Chemistry Arizona Radio Observatory, Tucson, AZ 85721; J. C. PEARSON AND B. J. DROUIN, Jet Propulsion Laboratory, Pasadena, CA 91109.

The N=1 1 and N=1 2 rotational transitions of CD, and the N=1 1 lines of ¹³CH have been measured in their ² _r ground electronic states using sub-mm direct absorption spectroscopy. The measurements below 600 GHz (CD: N=1 1 and ¹³CH: N=1 1) were carried out at Arizona, while those in the 900 GHz range were conducted at JPL (CD: N=1 1). The two radical species were created in an electrical discharge of either ¹³CH₄ or CD₄. Both lambda-doubling and hyperfine splitttings were resolved in the spectra. The data were analyzed with a case(b) effective Hamiltonian, resulting in an improvement in the lambda-doubling and deuterium, proton, and ¹³C hyperfine constants. Highly accurate rest frequencies are now available for astronomical searches for these species. CH is an abundant and widespread interstellar molecule, and thus CD and ¹³CH should be of astrophysical interest.