Ultrafast time-resolved x-ray absorption spectroscopy of ferrioxalate photolysis with a laser plasma x-ray source and microcalorimeter array

Abstract

Using a table-top apparatus based upon a laser plasma x-ray source and an array of cryogenic microcalorimeter x-ray detectors, we have measured the transient x-ray absorption spectrum during the ferrioxalate photoreduction reaction. We observe the Fe K edge move to lower energies, and the amplitude of the EXAFS features reduce, consistent with a photoreduction mechanism in which electron transfer precedes disassociation. These measurements results are compared to previously published transient x-ray absorption measurements on the same reaction, and found to be consistent with the results from Ogi \textit{et al} and inconsistent with the results of Chen \textit{et al}\cite{Ogi2015, Chen2007}. The high collection efficiency and performance improvements expected due to continued investment in microcalorimeter technology are good reasons to expect this technique to develop quickly.