MOLECULAR-BEAM INFRARED-SPECTROSCOPY AND INTRAMOLECULAR DYNAMICS OF SF5CCH IN THE REGION OF THE FUNDAMENTAL AND 1ST OVERTONE OF THE ACETYLENIC CH STRETCH

We have measured the high resolution spectrum of ethynylsulphurpentafluoride, SF5CCH, in both the fundamental and the first overtone of the acetylenic CH stretch in a collimated, supersonic molecular beam. The intramolecular redistribution of vibrational energy is discussed in relation to previous experimental results for other similar molecules and theoretical models. The absence of low order anharmonic resonances and the long (> 1 ns) lifetime derived from the spectra support a previously proposed correlation between these two molecular properties.