Collisional broadening and shifting of Raman lines, and the potential energy surface for H_2-Ar

摘要

Quantum mechanical close-coupling calculations of pressure broadened and pressure shifting coefficients for polarized vibrational Raman Q_1(j) and pure rotational S_0(j) Raman transitions of H_2-Ar and D_2-Ar have been performed using the empirically determined three-dimensional 'XC(fit)' potential energy surface. While the calculated Q_1(j) vibrational line shifting coefficients, and both the shifting and broadening coefficients for the pure rotational S_0(j) lines agree well with experiment, broadening coefficients calculated for the Q_1(j) transitions are substantially smaller than the measured values. Test calculations using ad hoc modifications of the XC(fit) potential indicate that the diatom stretching dependence of that potential energy surface needs further refinement.