Bulk-Sensitive Detection of the Total Ion Yield for X‑ray Absorption Spectroscopy in Liquid Cells

Detection of ionic current with two electrodes installed in a liquid cell has been established previously as an effective method, termed as total ion yield (TIY), to acquire X-ray absorption (XA) spectra of liquid solutions behind a membrane. In this study, the exact locations where TIY signals are generated are further investigated and unequivocally identified. The detected ionic current stems dominantly from the bulk solution species while only marginally from the species located at the membrane–solution interface. Such a two-electrode TIY detection in a liquid cell combines the advantages of bulk sensitivity of fluorescence yield and high signal strength (for light elements) of electron yield, exhibiting its novel and promising role in the XA spectroscopy measurements of liquid cells.