The Ultraviolet Absorption Spectrum of Thioformaldehyde

Abstract

<p> This work extends the knowledge about the excited electronic states of thioformaldehyde. Survey work is reported over the wavelength region from 230 nm to 180 nm and four electronic transitions are identified. These are assigned as the 1Al(π,π*), 1B2(n,3s), 1Al(n,3py) and 1B2(n,3pz) systems.</p> <p> A vibrational and rotational analysis of the first two systems has been undertaken. The results of these analyses indicate that the molecule remains planar or nearly so in both the 1Al(π,π*) and the 1B2 (n,3s) transitions. This behaviour is contrasted to that of similar molecules which are known to be non-planar in these electronic states and reasons are offered for this observation. The substituted geometry for thioformaldehyde in the 1B2(n,3s) state has been calculated and provides insight into the changes which occur in the molecule on electronic excitation.</p>