Electroactive Interface for Enabling Spectroelectrochemical Investigations in Evanescent-Wave Cavity-Ring-Down...

Area of Science:

• Physical Chemistry
• Spectroscopy
• Electrochemistry

Background:

• Spectroelectrochemical investigations require specialized interfaces for simultaneous optical and electrical measurements.
• Existing techniques may lack sensitivity or the ability to probe redox events at solid-liquid interfaces with high spatial resolution.

Purpose of the Study:

• To develop an electrically active interface for evanescent-wave cavity-ring-down spectroscopy (EW-CRDS).
• To enable spectroelectrochemical studies of redox events at solid-liquid interfaces.
• To demonstrate the platform's capability in analyzing molecular adsorption and redox processes.

Main Methods:

• Integration of a transparent conductive electrode (indium tin oxide) into the EW-CRDS platform.
• Spectroelectrochemical measurements using the developed EW-CRDS system.
• Kinetic adsorption analysis and cyclic voltammetry with synchronous optical readout.

Main Results:

• Achieved a cavity ring-down time of approximately 900 ns, suitable for spectroelectrochemical studies.
• Quantified adsorption/desorption constants, Gibbs free energy, and surface coverage for cytochrome c on various interfaces.
• Successfully measured electrode-driven redox events of surface-confined molecules at low coverages.

Conclusions:

• The electro-active EW-CRDS platform effectively enables spectroelectrochemical investigations of redox events.
• The technique allows for precise optical measurement of molecular behavior at solid-liquid interfaces.
• This development expands the applicability of EW-CRDS for studying electrochemical phenomena.