Rotationally inelastic scattering of two HF molecules

Abstract

For rotationally inelastic HF–HF collisions we have determined fully quantum partial opacities and integral cross sections for the j1=0, j2=0→11, 02, and 22 transitions at total energies of 500, 1000, and 8000 cm−1 and the 11→02 transition at 1000 cm−1. The potential was obtained from a recent fit of an ab initio surface and consisted of a spherically symmetric component and an anisotropic term with dipole–dipole symmetry. The collision dynamics were treated using the recently developed decoupled l-dominant (DLD) and coupled-states (CS) methods as well as within the Born approximation (BA). Comparison with selected full close-coupling calculations indicates that the CS method is very accurate for processes where collisions at small impact parameter play a large role, while the DLD method is to be preferred when large parameter collisions make the major contribution. The BA is, unfortunately, consistently unreliable, overestimating cross sections by more than an order of magnitude except at high energy. Additionally, the BA does not predict correctly the relative ratio of the 11→02 to 11→00 cross sections.

Isotopic variants of the atomic hydrogen + hydrogen reaction. 1. Total reaction cross sections of the atomic hydrogen + deuterium and atomic hydrogen + hydrogen deuteride reactions as a function of relative energy

“…Classical kinetic experiments have been carried out on isotopic versions of + H2 in which the temperature-dependent rate constant k(T) was measured. 10 The corresponding energies are near the threshold for the reaction, that is, in the region 0.4 to 0.6 eV. More recently a new class of experiments have been carried out involving some degree of state selection.…”

Investigation of an interferometric modulator based on channel waveguides in LiNbO3

“…However, because of the long-range dipole-dipole interaction first-order probabilities often exceed unity at small impact parameters; consequently, even when extra unitarising approximations such as that used by Cross and Gordon (1966) are employed, the theory often gives poor numerical agreement with experiment (Dagdigian et a1 1979, Dagdigian andAlexander 1980) and with 'exact' (i.e. converged close-coupling) theory (DePristo and Alexander 1977).…”