Two-photon (C)over-tilde 1B2(n, 4s) ← (X)over-tilde 1A1 absorption of thioformaldehyde as observed in (2+2) resonance enhanced multiphoton ionization spectroscopy

Two-photon C B-1(2)(n, 4s) <- <(X)over tilde> (1)A(1) absorption of methanethial (thioformaldehyde) H2CS has been probed by (2+2) resonance enhanced multiphoton ionization spectroscopy (REMPI) for the first time. The REMPI spectrum has a well developed rotational structure with O, P, Q, R, and S branches, which has been simulated using rotational constants reported by Moule and co-workers.