		15min:

LASER FLUORESCENCE EXCITATION SPECTROSCOPY OF THE Ar--HCO COMPLEX.

SCOTT A. WRIGHT AND PAUL J. DAGDIGIAN, Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218-2685.

The fluorescence excitation spectrum of the Ar--HCO van der Waals complex in the vicinity of the B²A'(000)~-- ~X²A'(000) band of free HCO is reported. At least 8 bands associated with the complex have been detected. We observe a spectral shift of the lowest energy Ar--HCO band with respect to the origin of the free HCO transition, and from this estimate the binding energy in the excited electronic state to be at least 10~cm^-1 greater than that in the ground state. Rotational analysis of some of the bands has been carried out, and average Ar-- HCO separations in both electronic states determined. Several of the bands were assigned as hot bands from the first excited bend-stretch level (K''~=~1) in the ground electronic state. Decay lifetimes of several Ar-- HCO~(B) levels were measured and were found to be somewhat smaller than those previously measured for free HCO.