Dynamic interference of photoelectrons produced by high-frequency laser pulses

TL;DR

This paper investigates how high-frequency laser pulses cause dynamic interference in photoelectrons due to the AC Stark effect, significantly altering the photoelectron spectrum with multi-peak patterns, supported by exact numerical and analytical results.

Contribution

It introduces a first-principles analysis of dynamic interference effects in high-frequency laser ionization, revealing the influence of the AC Stark effect on photoelectron energies and spectra.

Findings

Photoelectron energy follows the laser pulse envelope.

Dynamic interference causes multi-peak structures in spectra.

Analytical expressions predict spectral dependence on pulse properties.

Abstract

The ionization of an atom by a high-frequency intense laser pulse, where the energy of a single-photon is sufficient to ionize the system, is investigated from first principles. It is shown that as a consequence of an AC Stark effect in the continuum, the energy of the photoelectron follows the envelope of the laser pulse. This is demonstrated to result in strong dynamic interference of the photoelectrons of the same kinetic energy emitted at different times. Numerically exact computations on the hydrogen atom demonstrate that the dynamic interference spectacularly modifies the photoionization process and is prominently manifested in the photoelectron spectrum by the appearance of a distinct multi-peak pattern. The general theory is shown to be well approximated by explicit analytical expressions which allow for a transparent understanding of the discovered phenomena and for making predictions on the dependence of the measured spectrum on the properties of the pulse.