Table-top Nonlinear Extreme Ultraviolet Spectroscopy

TL;DR

This paper demonstrates the first second harmonic generation in the extreme ultraviolet range using a table-top source, enabling new element-specific spectroscopic studies with femtosecond resolution in smaller labs.

Contribution

It introduces the first table-top XUV SHG experiment, expanding nonlinear XUV spectroscopy beyond large-scale free electron lasers.

Findings

First observation of XUV SHG at Ti M2,3-edge

Confirmation of surface specificity and resonant enhancement via electronic structure calculations

Enables femtosecond, element-specific studies in smaller laboratories

Abstract

The lack of available table-top extreme ultraviolet (XUV) sources with high enough fluxes and coherence properties have limited the availability of nonlinear XUV and x-ray spectroscopies to free electron lasers (FEL). Here, we demonstrate second harmonic generation (SHG) on a table-top XUV source for the first time by observing SHG at the Ti M2,3-edge with a high harmonic seeded soft x-ray laser (HHG-SXRL) [1,2]. Further, this experiment represents the first SHG experiment in the XUV. First-principles electronic structure calculations are used to confirm the surface specificity and resonant enhancement of the SHG signal. The realization of XUV-SHG on a table-top source with femtosecond temporal resolution opens up tremendous opportunities for the study of element-specific dynamics in multi-component systems where surface, interfacial, and bulk-phase asymmetries play a driving role in smaller-scale labs as opposed to FELs.