On the argon–methane interaction from scattering data

Abstract

The Ar-HCl potential energy surface from a global map-facilitated inversion of state-to-state rotationally resolved differential scattering cross sections and rovibrational spectral dataThe rotational and vibrational dynamics of argon-methane. II. Experiment and comparison with theoryThe rotational and vibrational dynamics of argon-methane. I. A theoretical study J. Chem. Phys. 110, 5639 (1999); 10.1063/1.478462Neon-methane and argon-methane isotropic interaction potentials from total differential cross sections Total differential cross sections have been measured for Ar-CH. at E = 90.1 meV in the center of mass angular range from 5° to 55°. The well resolved rainbow m~ximum and .the s~perimposed rapid oscillations are used to establish a reliable isotropic interaction potentIal Vo(R). WIth thIS Vo(R). the torque and low temperature second virial coefficients are analyzed to establish constr~nts on the ~isotrop~c potential V3(R) which obeys tetrahedral symmetry. In a final step a complete potentIal surface IS det~rml.ned based o~ all three data sets. The scattering calculations are performed in the coupled-states approxImation for rotational state-to-state transitions which are summed for the total differential cross section. Small variations of anisotropic parameters lead to dramatic changes in the inelastic differential cross sections. while only small effects are observed in the total differential cross section.where R is the vector between the atom and molecule

Total differential cross sections for Ar–CH4 from an ab initio potential

“…We compare the results obtained from the asymptotically scaled and the non-scaled SAPT potentials with the experimental data from Ref. 4.…”

“…4. Total differential cross sections for Ar-CH 4 were also measured at slightly different collision energies. 6 Liuti et al 7 reported total integral cross sections for rare gas-methane scattering as functions of the velocity.…”

“…In their pioneering work [1][2][3] Secrest and coworkers applied both the closecoupling ͑CC͒ and coupled-states ͑CS͒ formalisms in the calculations of differential cross sections ͑DCS͒. Buck et al 4 measured total differential cross sections in a crossed beam experiment at E CM ϭ 90.1 meV. These results were used to derive an empirical potential of the Morse-spline-van der Waals type including the leading anisotropic contribution with tensor order lϭ3.…”

“…Time-of-flight ͑TOF͒ spectra were reported 5 and compared with CS calculations that used the potential from Ref. 4. Total differential cross sections for Ar-CH 4 were also measured at slightly different collision energies.…”

“…During the last few decades, a number of experimental and theoretical studies have been devoted to the rotationally elastic and inelastic scattering of Ar-CH 4 . In their pioneering work [1][2][3] Secrest and coworkers applied both the closecoupling ͑CC͒ and coupled-states ͑CS͒ formalisms in the calculations of differential cross sections ͑DCS͒.…”