Development of Surface Fluorescence X-Ray Absorption Fine Structure Spectroscopy Using a Laue-Type Monochromator

Area of Science:

• Surface science
• Materials science
• Spectroscopy

Background:

• Surface fluorescence X-ray absorption fine structure (XAFS) spectroscopy is crucial for analyzing low-concentration metals.
• Bulk scattering often interferes with surface XAFS measurements, especially in electrolyte environments.
• Existing methods struggle to isolate surface signals from strong bulk scattering.

Purpose of the Study:

• To develop a novel surface fluorescence XAFS spectroscopy technique capable of analyzing low-concentration metals on flat surfaces in electrolytes.
• To overcome the limitations of bulk scattering in traditional surface XAFS measurements.
• To enable in situ structural analysis of electrode surfaces.

Main Methods:

• Development of a surface fluorescence XAFS spectroscopy method utilizing a Laue-type monochromator.
• Implementation of a bent crystal Laue analyzer (BCLA) to suppress scattered X-rays from the bulk.
• Application of the technique to submonolayer platinum (Pt) on highly oriented pyrolytic graphite (HOPG) in electrolyte solutions.
• Integration with back-illuminated fluorescence XAFS (BI-FXAFS) spectroscopy.

Main Results:

• The BCLA effectively removed scattered X-rays from the bulk, even in the presence of solution.
• High signal-to-noise ratio in situ XAFS data was successfully obtained for submonolayer Pt on HOPG.
• The developed technique demonstrated feasibility for analyzing low-concentration metal species on flat electrode surfaces.

Conclusions:

• The developed surface fluorescence XAFS spectroscopy with a BCLA is a powerful tool for in situ structural analysis of low-concentration metals on flat surfaces in electrolytes.
• This technique significantly improves the signal quality by mitigating bulk scattering interference.
• It opens new avenues for studying interfacial phenomena in electrochemical systems.