Synchrotron infrared radiation for electrochemical external reflection spectroscopy: a case study using ferrocyanide

Area of Science:

• Electrochemistry
• Spectroscopy
• Materials Science

Background:

• Synchrotron infrared (IR) radiation offers high brilliance for spectroscopic analysis.
• Studying diffusion-controlled redox reactions requires sensitive and time-resolved techniques.

Purpose of the Study:

• To couple synchrotron IR radiation with an external reflectance cell for studying ferrocyanide redox diffusion.
• To compare time-resolved spectroscopic data with electrochemical responses.
• To analyze diffusion in axial and radial dimensions and its impact on measurements.

Main Methods:

• Utilizing synchrotron IR radiation coupled to an IR microscope and a thin-cavity external reflectance cell.
• Performing time-resolved spectroscopic studies of diffusion-controlled redox behavior.
• Comparing spectroscopic results with electrochemical measurements.

Main Results:

• Achieved excellent signal-to-noise ratios, even near the diffraction limit, due to high synchrotron brilliance.
• Observed marked differences between spectroscopic and electrochemical measurements.
• Explained discrepancies by analyzing axial and radial diffusion, noting IR interrogates perpendicular diffusion.

Conclusions:

• Synchrotron IR spectroscopy is effective for studying diffusion-controlled redox processes with high sensitivity.
• The technique provides insights into diffusion dynamics not fully captured by electrochemical methods alone.
• Applicable for studying electrochemical processes in the submillisecond domain, particularly with ultramicroelectrodes.