Close-coupling study of rotational energy transfer and differential scattering in H2O collisions with He atoms

摘要

Quantum close-coupling scattering calculations of rotational energy transfer(RET)of rotationally excited H2O due to collisions with He are presented for collision energies between 10~(-6)and 1000 cm-1 with para-H2O initially in levels 1_(1,1),2_(0,2),2_(1,10 and 2_(2,0)and ortho-H2O in levels 1_(1,0),2_(1,2)and 2_(2,1).Quenching cross sections and rate coefficients for state-to-state RET were computed.Both elastic and inelastic differential cross sections are also calculated and compared with relative experimental results giving generally good agreement in all cases,but less so for inelastic results.Significant differences in the computed collisional parameters,obtained on three different potential energy surfaces(PESs),were found particularly in the ultracold regime.In the thermal regime,the rate coefficients calculated on each of the surfaces are generally in better agreement and comparable,but typically larger,than those obtained in a previous calculation.Unfortunately,a lack of absolute differential or integral inelastic experimental data prevents firm determination of a preferred PES.