The rotational spectrum up to 1 THz and the molecular structure of thiomethylium, HCS+

Abstract

The rotational spectra of HCS⁺, DCS⁺, and HC³⁴S⁺ have been investigated using a newly constructed ion cell in selected regions between 0.46 and 0.94 THz. 23 transitions covering the quantum numbers 10 ⩽ J″ ⩽ 25 have been used in a combined fit together with previous data to improve the rotational and quartic centrifigal distortion constants B₀ and D₀, respectively. High J transitions have been measured specifically to obtain an estimate of the sextic distortion constant H₀. Vibration rotation coupling constants α_i were obtained from coupled cluster calculations. They were used to determine a mixed experimental/ab initio equilibrium structure r_e.