Rotational spectroscopy of the thioformaldehyde isotopologues H2CS and H2C34S in four interacting excited vibrational states and an account on the rotational spectrum of thioketene, H2CCS

Abstract

An investigation of the rotational spectrum of the interstellar molecule thioformaldehyde between 110 and 377 GHz through a pyrolysis reaction revealed a multitude of absorption lines assignable to H 2 CS and H 2 C 34 S in their lowest four excited vibrational states besides lines of numerous thioformaldehyde isotopologues in their ground vibrational states reported earlier as well as lines pertaining to several by-products. Additional transitions of H 2 CS in its lowest four excited vibrational states were recorded in selected regions between 571 and 1386 GHz. Slight to strong Coriolis interactions occur between all four vibrational states with the exception of the two highest lying states because both are totally symmetric vibrations. We present combined analyses of the ground and the four interacting states for our rotational data of H 2 CS and H 2 C 34 S. The H 2 CS data were supplemented with two sets of high-resolution IR data in two separate analyses. The v 2 = 1 state has been included in analyses of Coriolis interactions of low-lying fundamental states of H 2 CS for the first time and this improved the quality of the fits substantially. We extended furthermore assignments in J of transition frequencies of thioketene in its ground vibrational state.