High energy-resolution transient ghost absorption spectroscopy

TL;DR

This paper introduces a ghost spectroscopy method combined with pump-probe techniques to measure ultrafast charge carrier dynamics in silicon with high spectral resolution, overcoming free-electron laser fluctuations.

Contribution

It presents a novel high-resolution transient ghost absorption spectroscopy technique for ultrafast dynamics measurement.

Findings

Resolved small energy shifts in silicon absorption spectrum.

Demonstrated charge carrier relaxation dynamics.

Showed structural changes via spectral variations.

Abstract

We demonstrate the measurement of ultrafast dynamics using ghost spectroscopy and a pump-probe approach with an optical pump and a short-wavelength radiation probe. The ghost spectroscopy approach is used to overcome the challenge of the strong intensity and spectrum fluctuations at free-electron lasers and to provide high -spectral resolution, which enables the measurement of small energy shifts in the absorption spectrum. We exploit the high resolution to explore the dynamics of the charge carrier excitations and relaxations and their impact on the photoinduced structural changes in silicon by measuring the variation of the absorption spectrum of a Si(100) membrane near the silicon L2,3 edge and the accompanying edge shifts in response to the optical illumination.