Near-infrared laser absorption spectroscopy of the CS+ cation

The (1, 0) band of the A 2Π–X 2Σ+ transition of the CS+ cation has been measured in absorption at Doppler-limited resolution, between 12 400 and 13 000 cm−1. The spectrum was recorded using differential velocity modulation detection and a Ti: sapphire laser as the near-infrared light source. The v=1 A 2Π upper state of the band is perturbed by the v=10 level of the ground state. A deperturbation analysis using >300 rotational lines was carried out to derive accurate ground- and upper-state parameters. The ground-state rotational and fine-structure constants are in very good agreement with those from a Fourier transform emission study in which the ground-state constants were derived from combination differences.