In a crossed molecular beam experiment, time-of-flight distributions of HD-molecules scattered from Ne at an energy of 31.5 meV have been measured using the pseudorandom chopper method. Each time-of-flight spectrum shows a clearly resolved inelastic peak due to rotational excitation of HD from j=0 to j=1. With the aid of these spectra, together with additional measurements of the total differential cross section, the angular dependence of the differential cross section for the excitation j=0→1 is derived over a large angular range (20° to 120°). The sensitivity of the data to the interaction potential is carefully studied and the measured inelastic differential cross sections are compared with calculations based on interaction potentials recently proposed for this system.

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

Articles you may be interested inThe Ar-HCl potential energy surface from a global map-facilitated inversion of state-to-state rotationally resolved differential scattering cross sections and rovibrational spectral data Hard shape potentials from rotational statetostate inelastic cross sections: A possible route to inversion J. Chem. Phys. 94, 1167 (1991); 10.1063/1.460023Determining the anisotropic interaction potential of D2Ar from rotationally inelastic cross sections Differential cross sections for the rotational excitation from j = 0 to j = 2 of D2 scattered by N e have been measured at an energy of E = 84.9 meV. The experiments have been performed in a crossed nozzle beam apparatus with time-of-flight analysis of the scattered particles using the pseudorandom chopper method. A detailed analysis of the experimental data which are peaked in the backward direction showed that they are mainly sensitive to the repulsive part of the pure anisotropic potential. From a combined analysis of the stateto-state differential cross sections of the j = 0 to j = 0 and the j = 0 to j = 2 transition of D2 + N e and the j = 0 to j = I transition of HD + Ne previously measured, the complete potential energy surface for the hydrogen-neon system is obtained using the coupled states method. The anisotropic contribution varies from 37% of the isotropic part in the repulsive region (2.4 A) to 12% in the attractive region (3.5 A). The results differ from the other potential models derived for this system from calculations, spectroscopic studies, and bulk properties. However, it is in agreement with the results of a recently developed inversion method based on the exponential distorted wave approximation using the same experimental data. 5620

New, high resolution, differential collision cross section data for the scattering of He by Ar atoms, obtained in Göttingen, are found to be inconsistent with the predictions derived from a recently proposed He–Ar potential [M. Keil et al., J. Chem. Phys. 70, 482 (1979)] and confirm previous work by K. M. Smith et al. [J. Chem. Phys. 67, 152 (1977)]. It is shown that the He–Ar well depth is 29.4 K (accurate to 5% and 44% larger than the value of Keil et al.), independent of the parametrization of the potential. A careful analysis of the bulk properties of the He–Ar mixture also shows that the attractive part of the potential proposed by Keil et al. is too weak. A potential of the SPFD form is presented which is able to reproduce the best data for the differential cross section, the second virial coefficient, the diffusion and viscosity within the quoted experimental errors.

Differential cross sections are measured for rotational transitions j=0 to j′=0, 1 of HD+D2. Diffraction oscillations are resolved in the inelastic channel. (AIP)