Separation of Target Structure and Medium Propagation Effects in High-Harmonic Generation

TL;DR

This paper presents a method to separate target molecular structure from medium effects in high-harmonic generation spectra, enabling accurate structural imaging despite experimental variability.

Contribution

The study introduces a factorization approach that isolates target-specific information from HHG spectra, accounting for macroscopic propagation effects.

Findings

Accurately reproduces experimental HHG spectra with theoretical models.

Demonstrates the ability to extract target structure from HHG spectra.

Shows potential for ultrafast imaging of transient molecules.

Abstract

We calculate high-harmonic generation (HHG) by intense infrared lasers in atoms and molecules with the inclusion of macroscopic propagation of the harmonics in the gas medium. We show that the observed experimental spectra can be accurately reproduced theoretically despite that HHG spectra are sensitive to the experimental conditions. We further demonstrate that the simulated (or experimental) HHG spectra can be factored out as a product of a \macroscopic wave packet" and the photo-recombination transition dipole moment where the former depends on the laser properties and the experimental conditions, while the latter is the property of the target only. The factorization makes it possible to extract target structure from experimental HHG spectra, and for ultrafast dynamic imaging of transient molecules.