Coherent control ofH−photodetachment in parallel static electric and magnetic fields

Theoretical calculations of quantum interference effects occurring in photodetachement of ${\mathrm{H}}^{\mathrm{-}}$ with short-pulse lasers in the presence of a uniform static electric field [Q. Wang and A. F. Starace, Phys. Rev. A 48, R1741 (1993)] are examined in more detail and extended to the case of parallel static electric and magnetic fields. We show that modulation factors characterizing near-threshold cross sections resulting from detachment by relatively long laser pulses may be employed to set the parameters that are most effective for control of detachment cross-section magnitudes with short coherent laser pulses. Use of a static magnetic field to control detached electron wave-packet motion perpendicular to the static field axis is shown to increase greatly the magnitude of quantum interference effects on the cross sections (from 10% of the field-free cross section in an optimized static electric-field case to 50% in a parallel static electric and magnetic-field case). Theoretical dependence of calculated cross sections on laser pulse lengths, time delays, relative phases, frequencies, and classical electron orbit times are presented and discussed in detail.