Intermolecular interactions of H_2S with rare gases from molecular beam scattering in the glory regime and from ab initio calculations

摘要

Integral cross sections for collisions of rotationally hot H_2S molecules with rare gas atoms (Ne,Ar,and Kr) have been measured,in the collision energy range of 10-60 kJ mol~(-1),using a molecular beam apparatus operating under high resolution both in angle and in velocity.A well resolved glory pattern has been measured which permitted the accurate characterization of the intermolecular potentials both at long range (in the attractive region) and at intermediate distances (in the well region).Considering the conditions used in the experiments,the obtained potentials must be considered very close to the spherical averages of the full intermolecular potential energy surfaces.Extensive ab initio calculations have also been carried out in parallel in order to characterize energy minima in the potential energy surfaces and energy barriers associated to the motion of the rare gas atoms around H_2S.An assessment of the relative role of the various interaction components has been also attempted:the combined analysis of experimental and theoretical results suggests that H_2S-rare gas aggregates are mainly bound by nearly isotropic noncovalent interactions of the van der Waals type.