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

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