Resonance enhanced multiphoton ionization spectroscopy of jet cooled (CS2)-C-12-S-32 and (CSS)-C-12-S-34-S-32 from 45,500 to 48,000 cm(-1)

The (1+1) resonance enhanced multiphoton ionization spectra of jet-cooled C S2 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 diffe rent expansion gases which resulted in varying degrees of vibrational cooli ng and the comparison of the two isotopomer spectra, a partial assignment o f 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 4 6 248.7 cm(-1) and values for the predissociation lifetimes for the upper s tate for 34 vibrational bands and isotopomer shifts of seven vibrational le vels 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) ban ds. A simulation of the spectrum, which used the harmonic approximation, is in qualitative agreement with the band positions and shifts, but quantitat ive 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-l ying predissociating levels of CS2, which will be of use in future photofra gment studies. (C) 1999 American Institute of Physics. [S0021-9606(99)00916 -2].