New Probes of the Electrochemical Interface: 'Atomic' EXAFS and Fano Resonances in X-ray Absorption Spectroscopy

摘要

The main reason for the lack of detailed information on the bonding of adsorbed species in an electrochemical cell is the absence of a general in situ spectroscopic technique that can provide electronic structure information. X-ray absorption spectroscopy (XAS) is one spectroscopic technique that can be applied in situ, because XAS is one of only a few probes that utilizes photons exclusively (i.e. photons in and photons out, when using transmission or fluorescence yield mode). However, XAS has been limited until recently to providing geometric information on systems with short-range order (via X-ray absorption fine structure- XAFS). X-ray diffraction (XRD) is similar in this regard, but it requires long-range order and provides only geometric information as well. X-ray photoelectron spectroscopy (XPS), and any other electron spectroscopy such as Auger, provides electronic structure information but requires ultra-high vacuum conditions. The stimulus for this work is recent advances in XAS (in both XAFS and XANES) that now enables XAS to also provide electronic structure information.