Formula for laser pulse photodetachments of negative ions

We express the detachment cross section caused by a Gaussian pulsed laser i n terms of that caused by a continuous laser. Using this expression and Poi sson's summation formula, we derive a uniform semiclassical formula for the cross section of pulsed-laser photodetachment of a hydrogen ion H- in Stat ic parallel electric and magnetic fields. The uniform semiclassical formula does not have a divergence problem at the bifurcation points. Numerical co mparisons show an excellent agreement between the uniform semiclassical for mula and the quantum formula for the detachment cross section.