STIMULATED RAMAN-SPECTRA OF JET-COOLED ETHYLENE

We have recorded stimulated Raman spectra of the central region of the nu1 band of ethylene, both in a jet at temperatures down to almost-eq ual-to 25 K, and in a static cell at room temperature and at almost-eq ual-to 173 K. The rotational temperatures of the jet are estimated by computer simulation of the observed spectra. Only Q branches are recor ded in this experiment. A vib-rotational analysis is performed and imp roved values are obtained for the band origin and the rotational const ants of the nu1 = 1 state of this molecule. Some perturbations are fou nd to affect the rotational levels of this state.