Vibrational predissociation dynamics of ArHF (3000) and (3110): Lifetimes and HF product state distributions

The lifetimes and HF (upsilon=2) product rotational distributions (j'=13 to 9) arising from the vibrational predissociation of ArHF (3000) and (3110) states have been determined by laser-induced dispersed fluorescence. The lifetimes of (3000) and (3110) are found to be 3.9(4)x10(-6) and 7.3(8)x10(-6) s, respectively, showing both intermolecular vibration and HF valence state dependence. The variation in the vibrational predissociation rate for these two states indicates a strong angular dependence of the change of interaction potential with the HF internuclear distance in the complex. The product state distribution of ArHF (upsilon=3) reveals the excess energy, 3380 cm(-1), resulting from vibrational predissociation (Delta upsilon=-1) is partitioned primarily into HF product rotation. The rotational distribution observed following excitation of the (3110) level is considerably broader than the relatively sharply peaked distribution from (3000). The upsilon(HF)=3 ground stare, (3000), vibrationally predissociates into j'=13 at a rate of tau(vp)=1.2x10(5) s(-1), which is one half of the rate of predissociation to all states. (C) 1998 American Institute of Physics. [S0021-9606(98)00644-8].