State-to-state rotational rate constants of CO+He:Infrared double resonance measurements and simulation of the data using the SAPT theoretical potential energy surface

摘要

An extensive data set of 54 time-resolved pump-probe measurements was used to examine CO+He rotational energy transfer within the CO v=2 rotational manifold.Rotational levels in the range J_i=2-9 were excited and collisional energy transfer of population to the levels J_f=1-10 was monitored.The resulting data set was analyzed by fitting to numerical solutions of the master equaition.State-to-state rate constant matrices were generated using fitting law functions and ab initio theoretical calculations that employed the SAPT potential energy surface of Heijmen et al.[J.Chem.Phys.107,9921 (1997)].Fitting laws based on the modified exponential gap (MEG),statistical power exponential gap (SPEG),and energy corrected sudden with exponential power (ECS-EP) models all yielded acceptable simulations of the kinetic data,as did the theoretical rate constants.However,the latter were unique in their ability to reproduce both our kinetic data and the pressure broadening coefcients for CO+He.These results provide an impressive demonstration of the quality of the symmetry adapted perturbation theory (SAPT) potential energy surface.