Precise Millimeter-wave Laboratory Frequencies for Cs and C34s

Nine successive rotational lines in the ground vibrational state of CS and C34S between 96 GHz (J 1⁄4 2 1) and 500 GHz (10–9) were measured in the laboratory to an accuracy of a few kHz. When our measurements are combined with the submillimeter-wave measurements of Ahrens & Winnewisser, the entire rotational spectrum of both isotopic species is predicted to an accuracy of about 1 part in 108 up to 500 GHz and 5 parts in 108 near 1000 GHz. These frequencies should be useful for quantitative studies of cloud core collapse and star formation in the millimeterand submillimeter-wave bands. Subject headings: ISM: molecules — methods: laboratory — molecular data — molecular processes — radio lines: ISM — stars: formation