Effect of molecular anisotropy on beam scattering measurements
Abstract
Within the energy sudden approximation the total integral and total differential scattering cross sections are given by the angle average of scattering cross sections computed at fixed rotor orientations. Using this formalism we have examined the effect of molecular anisotropy on scattering of He by HCl and by CO. Comparisons with accurate close coupling calculations indicate that this approximation is quite reliable, even at very low collision energies, for both of these systems. Comparisons are also made with predictions based on the spherical average of the interaction. For HCl the anisotropy is rather weak and its main effect is a slight quenching of the oscillations in the differential cross sections relative to predictions of the spherical averaged potential. For CO the anisotropy is much stronger, so that the oscillatory pattern is strongly quenched and somewhat shifted. It appears that the sudden approximation provides a simple yet accurate method for describing the effect of molecular anisotropy on scattering measurements.
 Publication:

Journal of Chemical Physics
 Pub Date:
 July 1978
 DOI:
 10.1063/1.436623
 Bibcode:
 1978JChPh..69..598G
 Keywords:

 Anisotropy;
 GasGas Interactions;
 Molecular Beams;
 Molecular Collisions;
 Scattering Cross Sections;
 Carbon Monoxide;
 Helium;
 Hydrogen Chlorides;
 Atomic and Molecular Physics;
 34.50.Lf;
 Chemical reactions energy disposal and angular distribution as studied by atomic and molecular beams