Background-free Tracking of Ultrafast Hole and Electron Dynamics with XUV Transient Grating Spectroscopy

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Main Authors: Eggers, Vincent, Quintero-Bermudez, Rafael, Xiong, Kevin Gulu, Leone, Stephen R.
Format: Preprint
Published: 2026
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_version_ 1866909053593059328
author Eggers, Vincent
Quintero-Bermudez, Rafael
Xiong, Kevin Gulu
Leone, Stephen R.
author_facet Eggers, Vincent
Quintero-Bermudez, Rafael
Xiong, Kevin Gulu
Leone, Stephen R.
contents Extreme ultraviolet (XUV) transient absorption (TA) and transient reflectivity (TR) spectroscopies enable element-specific insights into attosecond-timescale processes in solids. XUV transient grating spectroscopy (TGS) is an emerging tool that combines the advantages of both absorption and reflectivity while offering intrinsically background-free detection. Here, we implement XUV-TGS by generating a transient grating in germanium solid using two few-cycle near-infrared pulses and probing it with an attosecond XUV pulse, produced via tabletop high-harmonic generation. The spectrally resolved, diffracted XUV pulses directly visualize the separate ultrashort decay times of both photoexcited electrons and holes, without the need for iterative deconvolution. By combining XUV-TA and -TG spectroscopy, we extract the evolution of the complex refractive index, ñ, without the need for Kramers-Kronig reconstruction, as required in XUV-TR, allowing us to extract the roots of the induced optical response. We find reflectivity changes of up to 34% via the real part of ñ, whereas changes in the imaginary part only result in a variation in reflectivity of around 0.5%.
format Preprint
id arxiv_https___arxiv_org_abs_2602_09565
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Background-free Tracking of Ultrafast Hole and Electron Dynamics with XUV Transient Grating Spectroscopy
Eggers, Vincent
Quintero-Bermudez, Rafael
Xiong, Kevin Gulu
Leone, Stephen R.
Optics
Materials Science
Chemical Physics
Extreme ultraviolet (XUV) transient absorption (TA) and transient reflectivity (TR) spectroscopies enable element-specific insights into attosecond-timescale processes in solids. XUV transient grating spectroscopy (TGS) is an emerging tool that combines the advantages of both absorption and reflectivity while offering intrinsically background-free detection. Here, we implement XUV-TGS by generating a transient grating in germanium solid using two few-cycle near-infrared pulses and probing it with an attosecond XUV pulse, produced via tabletop high-harmonic generation. The spectrally resolved, diffracted XUV pulses directly visualize the separate ultrashort decay times of both photoexcited electrons and holes, without the need for iterative deconvolution. By combining XUV-TA and -TG spectroscopy, we extract the evolution of the complex refractive index, ñ, without the need for Kramers-Kronig reconstruction, as required in XUV-TR, allowing us to extract the roots of the induced optical response. We find reflectivity changes of up to 34% via the real part of ñ, whereas changes in the imaginary part only result in a variation in reflectivity of around 0.5%.
title Background-free Tracking of Ultrafast Hole and Electron Dynamics with XUV Transient Grating Spectroscopy
topic Optics
Materials Science
Chemical Physics
url https://arxiv.org/abs/2602.09565