Photodetachment ofH−by a short laser pulse in crossed static electric and magnetic fields

Abstract

We present a detailed quantum mechanical treatment of the photodetachment of H − by a short laser pulse in the presence of crossed static electric and magnetic fields.An exact analytic formula is presented for the final state electron wave function (describing an electron in both static electric and magnetic fields and a short laser pulse of arbitrary intensity). In the limit of a weak laser pulse, final state electron wave packet motion is examined and related to the closed classical electron orbits in crossed static fields predicted by Peters and Delos [Phys. Rev. A 47, 3020 (1993)].Owing to these closed orbit trajectories, we show that the detachment probability can be modulated, depending on the time delay between two laser pulses and their relative phase, thereby providing a means to partially control the photodetachment process. In the limit of a long, weak pulse (i.e., a monochromatic radiation field) our results reduce to those of others; however, for this case we analyze the photodetachment cross section numerically over a much larger range of electron kinetic energy (i.e., up to 500 cm −1 ) than in previous studies and relate the detailed structures both analytically and numerically to the above-mentioned, closed classical periodic orbits.

Strong-field photodetachment of H−by few-cycle laser pulses

“…One of the main strengths of the GK theory is that it yields very reliable quantitative results over a wide range of laser intensities and frequencies for both the perturbative and nonperturbative regimes. Increasing interest in the role the CEP plays in the photodetachment of negative atomic ions in few-cycle laser pulses [15][16][17][18][19][20] motivated us recently to adapt the GK formalism to ultrashort linearly polarized pulses [21]. There we showed that application of the saddle-point method to the amplitude for a laser pulse with N optical cycles [e.g., of the form A(t) ∝ sin 2 (ωt/2N ) sin(ωt + α)] produces 2(N + 1) saddle points in complex time.…”

Closed-orbit theory for the photodetachment rate in a static magnetic field transversely superimposed to an oscillatory electric field

“…Second η 1 ⇔ ω B ω, in this limiting situation the slowly varying electric field can be considered as constant since the time scale is dominated by the synchrotron frequency, i.e. both fields can be considered as static [17,18,32]. Third η ≈ 1 ⇔ ω B ≈ ω, this is perhaps the most interesting case, the time scale of the magnetic field effects is akin to that of the electric field and both effects compete.…”

“…The main motivation of this work is to study the effects of the transverse magnetic field in the generation of closed trajectories, and their manifestation in the photodetachment modulation. We consider as references the limiting cases of no magnetic field [23,31], as well as the case of perpendicular static electric and magnetic fields [17,18,32], and we discuss the differences.…”