Extraction of the species dependent dipole moment from high-order harmonic spectra in rare gas atoms

TL;DR

This paper demonstrates that high-order harmonic generation spectra can be used to extract species-dependent dipole moments and structural information of atoms, enabling insights into complex systems' structure and dynamics.

Contribution

It introduces a quantitative method to relate HHG spectra to photo-recombination cross sections and shows the potential to study complex systems' structure and evolution.

Findings

HHG yield can be expressed as a product of a wave packet and recombination cross sections.

The shape of the returning electron wave packet is largely species-independent.

Accurate structural information, including phase, can be retrieved from HHG spectra.

Abstract

Based on high-order harmonic generation (HHG) spectra obtained from solving the time-dependent Schrodinger equation for atoms, we established quantitatively that the HHG yield can be expressed as the product of a returning electron wave packet and the photo-recombination cross sections, and the shape of the returning wave packet is shown to be largely independent of the species. By comparing the HHG spectra generated from different targets under identical laser pulses, accurate structural information, including the phase of the recombination amplitude, can be retrieved. This result opens up the possibility of studying the target structure of complex systems, including their time evolution, from the HHG spectra generated by short laser pulses.