Professor Josh Vura-Weis of the University of Illinois

"What did the metals know, and when did they know it? Tabletop M-edge XANES reveals femtosecond dynamics in transition metal complexes"

X-ray absorption near edge spectroscopy (XANES) is a powerful technique for electronic structure determination. Recent developments in extreme ultraviolet (XUV) light sources using the laser-based technique of high-harmonic generation have enabled core-level spectroscopy to be performed on femtosecond to attosecond timescales. We have extended the scope of tabletop XUV spectroscopy and demonstrated that M2,3-edge XANES, corresponding to 3p→3d transitions, can reliably measure the electronic structure of first-row molecular transition metal complexes with femtosecond time resolution. We use this ability to track the excited-state relaxation pathways of photocatalysts and chromophores, uncovering hidden loss mechanisms and providing new design principles for transition metal photochemistry.