Near-threshold rotational excitation of molecular ions by electron impact
Abbreviated Journal Title
J. Phys. B-At. Mol. Opt. Phys.
QUANTUM-DEFECT THEORY; SCATTERING; COLLISIONS; DYNAMICS; MATRIX; H-3(+); Optics; Physics, Atomic, Molecular & Chemical
New cross sections for the rotational excitation of H-3(+) by electrons are calculated ab initio at low impact energies. The validity of the adiabatic-nuclei-rotation (ANR) approximation, combined with R-matrix wavefunctions, is assessed by comparison with rovibrational quantum defect theory calculations based on the treatment of Kokoouline and Greene (2003 Phys. Rev. A68 012703). Pure ANR excitation cross sections are shown to be accurate down to threshold, except in the presence of large oscillating Rydberg resonances. These resonances occur for transitions with Delta J = 1 and are caused by closed-channel effects. A simple analytic formula is derived for averaging the rotational probabilities over such resonances in a 3-channel problem. In accord with the Wigner law for an attractive Coulomb field, rotational excitation cross sections are shown to be large and finite at threshold, with a significant but moderate contribution from closed-channels.
Journal of Physics B-Atomic Molecular and Optical Physics
"Near-threshold rotational excitation of molecular ions by electron impact" (2006). Faculty Bibliography 2000s. 6123.