Micro-focused MHz pink beam for time-resolved X-ray emission spectroscopy

J Synchrotron Radiat. 2019 Nov 1;26(Pt 6):1956-1966. doi: 10.1107/S1600577519012268. Epub 2019 Oct 18.

Abstract

The full radiation from the first harmonic of a synchrotron undulator (between 5 and 12 keV) at the Advanced Photon Source is microfocused using a stack of beryllium compound refractive lenses onto a fast-moving liquid jet and overlapped with a high-repetition-rate optical laser. This micro-focused geometry is used to perform efficient nonresonant X-ray emission spectroscopy on transient species using a dispersive spectrometer geometry. The overall usable flux achieved on target is above 1015 photons s-1 at 8 keV, enabling photoexcited systems in the liquid phase to be tracked with time resolutions from tens of picoseconds to microseconds, and using the full emission spectrum, including the weak valence-to-core signal that is sensitive to chemically relevant electronic properties.

Keywords: MHz repetition rate; X-ray emission spectroscopy; beryllium lenses; pump/probe; solution dynamics; synchrotron; time-resolved.