Resonance enhanced multiphoton ionization spectroscopy of jet cooled C3212S2 and C3212S32S from 45 500 to 48 000 cm−1

The (1+1) resonance enhanced multiphoton ionization spectra of jet-cooled CS2 were obtained between 45 500 and 48 000 cm−1 (220–208 nm) for the two isotopomers C3212S2 and C3212S32S. With the use of different expansion gases which resulted in varying degrees of vibrational cooling and the comparison of the two isotopomer spectra, a partial assignment of the C̃ 1B2–X̃ 1Σg+ transition was obtained. The electronic origin of this transition is confirmed to lie at 46 248.7 cm−1 and values for the predissociation lifetimes for the upper state for 34 vibrational bands and isotopomer shifts of seven vibrational levels of the B21 state are presented. The lifetimes of the Σ0 bands were found to be larger than those of corresponding Π1 and Δ2 bands. A simulation of the spectrum, which used the harmonic approximation, is in qualitative agreement with the band positions and shifts, but quantitative disagreement between the values leads us to conclude that a normal mode analysis is not appropriate to describe the low vibrational levels of the B21 state. The results presented increase our understanding of the low-lying predissociating levels of CS2, which will be of use in future photofragment studies.