Ad. Peters et al., CLOSED-ORBIT THEORY AND THE PHOTODETACHMENT CROSS-SECTION OF H- IN PARALLEL ELECTRIC AND MAGNETIC-FIELDS, Physical review. A, 56(1), 1997, pp. 331-344
In this paper we obtain a simple analytic formula for the photodetachm
ent cross section of H- in parallel electric and magnetic fields. The
three-dimensional semiclassical approximation predicts oscillations in
the spectrum and correlates these oscillations with closed classical
orbits. The cylindrical symmetry of the Hamiltonian produces some inte
resting effects. In particular, at boundary energies the semiclassical
approximation fails as a focused cusp approaches the origin.