Anomalous photoelectron spectrum caused by finite interaction time in few-cycle xuv laser pulses

TL;DR

This paper investigates how finite interaction time in few-cycle XUV laser pulses causes an anomalous red shift in the photoelectron spectrum of hydrogen, revealing new effects when pulse durations are very short.

Contribution

It demonstrates that insufficient interaction time leads to a red shift in photoelectron spectra, a novel finding in the context of ultrashort laser-atom interactions.

Findings

Red shift in photoelectron spectrum due to short pulse duration

Shift magnitude increases as pulse duration decreases

Interaction time limits electron energy gain

Abstract

With the development of laser technology, pulse length enters the optical cycle regime and hence the interaction time between laser pulse and atoms becomes prominent. We investigate this problem in this Letter through the photoelectron spectrum of hydrogen atom in few-cycle xuv laser pulses. By solving one-dimensional time-dependent Schr\"odinger equation, we find that due to the insufficient interaction time, the electron can not gain enough energy from optical field when escaping the bind of the nuclear and then the abnormality appears in the photoelectron spectrum: the peak of photoelectron spectrum shows red shift compared with the well-known Einstein photo-electric effect formula. The shift becomes large as the pulse duration decreases.