Role of the Ionic Potential in High Harmonic Generation

TL;DR

This paper investigates how the ionic potential influences high harmonic generation in argon atoms, revealing the ionic core's significant role in electron dynamics and emitted light properties through polarization manipulation and spatiotemporal analysis.

Contribution

It decouples the steps of high harmonic generation to specifically analyze the ionic potential's role, highlighting Coulomb focusing effects.

Findings

Ionic core significantly affects all steps of high harmonic generation.

Coulomb focusing causes angular deflection of electrons before recombination.

Spatiospectral analysis shows the potential's influence on emitted light properties.

Abstract

Recollision processes provide direct insight into the structure and dynamics of electronic wave functions. However, the strength of the process sets its basic limitations - the interaction couples numerous degrees of freedom. In this Letter we decouple the basic steps of the process and resolve the role of the ionic potential which is at the heart of a broad range of strong field phenomena. Specifically, we measure high harmonic generation from argon atoms. By manipulating the polarization of the laser field we resolve the vectorial properties of the interaction. Our study shows that the ionic core plays a significant role in all steps of the interaction. In particular, Coulomb focusing induces an angular deflection of the electrons before recombination. A complete spatiospectral analysis reveals the influence of the potential on the spatiotemporal properties of the emitted light.