XUV-initiated high harmonic generation: driving inner valence electrons using below-threshold-energy XUV light

TL;DR

This paper introduces a new method using below-threshold XUV pulses to distinguish the roles of inner- and outer-valence electrons in high-harmonic generation in neon, enhancing understanding of electron dynamics.

Contribution

It presents a novel scheme to selectively probe inner-valence electron contributions in high-harmonic generation using low-energy XUV pulses and classical trajectory modeling.

Findings

Successfully suppresses 2p recollision trajectories

Resolves 2s electron contribution to HHG spectrum

Provides an intuitive classical trajectory understanding

Abstract

We propose a novel scheme for resolving the contribution of inner- and outer-valence electrons in XUV-initiated high-harmonic generation in neon. By probing the atom with a low energy (below the 2s ionisation threshold) ultrashort XUV pulse, the 2p electron is steered away from the core, while the 2s electron is enabled to describe recollision trajectories. By selectively suppressing the 2p recollision trajectories we can resolve the contribution of the 2s electron to the high-harmonic spectrum. We apply the classical trajectory model to account for the contribution of the 2s electron, which allows for an intuitive understanding of the process.