ROTATIONALLY MEDIATED INTRAMOLECULAR VIBRATIONAL REDISTRIBUTION IN JET-COOLED TRANS-ETHANOL AT 2990 CM-1

Rotationally resolved infrared absorption spectra of jet-cooled ethanol reveal extensive mixing of the zero-order methyl C-H stretch vibration with bath rotational-vibrational states. The fragmentation of single rotational lines into a multiplet of molecular eigenstates is the spectroscpic signature of intramolecular vibrational redistribution (IVR). The number of resolved molecular eigenstates increases from about 2 at J′ = 0 to about 20 at J′ = 4 but is independent of Ka′. The density of spectral features suggests that the IVR explores both the gauche and the trans forms of ethanol and that Ka′ is not a good quantum number. © 1990 American Chemical Society.