Environment-Dependent Radiation Damage in Atmospheric Pressure X-ray Spectroscopy

Area of Science:

• Surface Science
• Materials Chemistry
• Spectroscopy

Background:

• Soft X-ray spectroscopy offers interface-sensitive chemical insights into solids in gas/liquid environments.
• X-ray illumination of dense phases can induce radiolysis, generating reactive radical species.
• Radiolysis can significantly alter the chemical state of the surface being studied.

Purpose of the Study:

• To investigate the impact of X-ray-induced radiolysis on the oxidation states of Cu and Ni films.
• To understand how different environments (air, aqueous solutions) affect X-ray spectroscopy measurements.
• To identify mitigation strategies for radiolysis effects in operando X-ray measurements.

Main Methods:

• Soft X-ray absorption spectroscopy was used to analyze Cu and Ni films.
• Experiments were conducted in air, aqueous NaOH, and aqueous NaHCO3 solutions.
• Electrochemical cycling was employed to study Ni film stability.

Main Results:

• Cu films oxidized to CuO in air and NaOH, but reduced to Cu2O with methanol addition.
• Ni films in NaHCO3 remained stable and could be electrochemically cycled.
• The observed behaviors were explained by the products of X-ray-induced radiolysis.

Conclusions:

• X-ray radiolysis significantly affects the oxidation state of Cu films in various environments.
• Ni films exhibit greater stability under X-ray illumination in NaHCO3 solutions.
• Understanding radiolysis is crucial for accurate operando X-ray spectroscopy, and mitigation strategies are proposed.