2008ApJ...679..920B

The submillimeter-wave spectrum of the CS⁺ radical cation in its ground electronic state (X²Σ⁺) has been observed for the first time, in a flowing positive column discharge in a CS₂-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 B₀=25908.8560(41) MHz, D₀=41.344(18) kHz, and γ₀=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.