HIGH-OVERTONE SPECTROSCOPY AND PHOTODISSOCIATION OF HYDROGEN-FLUORIDE COMPLEXES

Intracavity laser-induced fluorescence investigations of the HF(upsilon = 3) states of hydrogen fluoride binary complexes have been summarized. Together with the previous measurements made by other authors at lower stretching states, our present investigations of ArHF, N2HF, (HF)(2) and HFHCl allow several global features of the weakly bound complexes upon valence vibrational excitation to be obtained. It is found for all four complexes that both the Van der Waals bond strength and the B rotational constant increase smoothly with upsilon. The effects are more pronounced in the complexes where HF acts as a hydrogen donor (bound HF) rather than as an acceptor (free HF). Additionally vibrational predissociation rates show a regular increase in upsilon when the bound-HF stretch is vibrationally excited, contrary to the complex pattern in the excitation of free HF. From upsilon = 1 to upsilon = 3, the increase of the predissociation rate in the bound-HF stretch is much greater than linear but somewhat less than geometric.