Resonance enhanced multiphoton ionization spectroscopy of jet cooled 12C32S2 and 12C34S32S 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 (CS2)-C-12-S-32 and (CSS)-C-12-S-34-S-32. 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 (C) over tilde B-1(2) - (X) over tilde (1)Sigma(g)(+) 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 B-1(2) state are presented. The lifetimes of the Sigma(0) bands were found to be larger than those of corresponding Pi(1) and Delta(2) 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 B-1(2) state. The results presented increase our understanding of the low-lying predissociating levels of CS2, which will be of use in future photofragment studies. (C) 1999 American Institute of Physics. [S0021-9606(99)00916-2].