Transient X‐Ray Absorption Near Edge Structure Spectroscopy Using Broadband Free‐Electron Laser Pulses

Abstract

A new method for time‐resolved X‐ray absorption near edge structure (XANES) spectroscopy that enables faster data acquisition and requires smaller sample quantities for high‐quality data, thus allowing the analysis of more samples in a shorter time is introduced. The method uses large bandwidth free electron laser pulses to measure laser‐excited XANES spectra in transmission mode. A beam‐splitting grating configuration allows simultaneous measurements of the spectra of the incoming X‐ray Free Electron Laser (XFEL) pulses and transmission XANES, which is crucial for compensating the pulse‐dependent intensity and spectrum fluctuations due to the self‐amplified spontaneous emission operation. The implementation of this new methodology is applied on a liquid solution of ammonium iron(III) oxalate jet and is compared to previous results, showing great improvements in the speed of acquisition and spectral resolution, and the ability to measure a large 2‐D spectral‐time map quickly.