X-ray induced photocurrents at the metal/solution interface

A technique is herein described for the acquisition of X-ray absorption spectra of electrodes fully immersed in an electrolyte solution by monitoring the energy dependence of X-ray induced photocurrents. This novel strategy made it possible to obtain in situ Au L_III-edge X-ray absorption spectra of solid Au electrodes displaying virtually identical features to those recorded simultaneously via X-ray fluorescence. The dependence of the X-ray induced photocurrents on chopping frequency and electrode potential was found to be consistent with a temperature modulation of the rate of the interfacial electron transfer (faradaic heating currents), rather than electron photoemission, as the primary source of the observed effects.