Analyzing the Photodetachment Cross Section of H^- in Parallel Electric and Magnetic Fields

We studied the photodetachment of H^- in the presence of parallel electric and magnetic fields. This system is an important model that demonstrates the effects of closed-orbits and their bifurcations on the quantum spectra. Using Poisson's summation formula, we have obtained a reduction formula that represents the cross section a sum of oscillations. The reduction formula is valid uniformly. We compare it with the predication from the closed-orbit theory.