Fourier transform infrared spectra of H 2CS and D 2CS

Abstract

Infrared spectra of thoformaldehyde, H 2CS and D 2CS, were observed in the gas phase at a resolution of better than 0.1 cm −1 from 4000 to 400 cm −1 using a Nicolet FTIR system. Vibrational band origins and rotational constants were determined for ν 2, ν 3, ν 4, and ν 6 of H 2CS and for ν 1, ν 2, ν 3, ν 4, and ν 6 of D 2CS. The ν 3, ν 4, and ν 6 bands of H 2CS were analyzed as a set of three Coriolis interacting bands, and three Coriolis constants were determined; similarly the ν 4 and ν 6 bands of D 2CS were analyzed as a pair of interacting bands and one Coriolis constant was determined. A general harmonic force field was determined, without constraints, to fit the vibrational wavenumbers, Coriolis constants, and centrifugal distortion constants. A zero-point ( r z ) structure was determined from the ground-state rotational constants, and the equilibrium ( r e ) bond lengths were estimated.