The Submillimeter‐Wave Spectrum of the CS+Radical Ion

The submillimeter-wave spectrum of the CS + radical cation in its ground electronic state ( X 2 Σ + ) has been observed for the first time, in a flowing positive column discharge in a CS 2 -Ar mixture partially cooled with a limited flow of liquid nitrogen. Nine rotational transition frequencies were recorded between 414 and 622 GHz, leading to the determination of accurate molecular constants B 0 = 25908.8560(41) MHz, D 0 = 41.344(18) kHz, and γ 0 = 597.629(41) MHz, which we use to predict transition frequencies up to the terahertz region in order to stimulate new attempts at astronomical detection.