INFRARED INFRARED DOUBLE-RESONANCE SPECTROSCOPY OF AR-HF - INTERMOLECULAR STATE DEPENDENCE OF THE DIPOLE-MOMENT AND VIBRATIONAL PREDISSOCIATION IN UPSILON-HF=2

Stark spectra have been measured for Ar-HF in several excited intermolecular bending and stretching states associated with upsilon(HF)=1. The resulting dipole moments are compared with those calculated using the most recent potential energy surface. Infrared-infrared double resonance spectroscopy is used to access the corresponding states in upsilon(HF)=2 where, in the absence of intermolecular excitation, dissociation occurs before the molecules can reach the detector. Simultaneous excitation of the SIGMA or PI bending vibrations, which have the effect of making the hydrogen atom point away from argon atom on average, results in lifetimes in excess of the molecular flight time (0.3 ms).