ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY APPLIED TO IN SITU STRESS MEASUREMENTS

Manon C. Lafouresse, Gery R. Stafford, and Ugo Bertocci

 

Monitoring the curvature of a cantilever in solution and under potential control is a well-established method for studying the surface stress at the electrolyte-electrode interface. These in situ stress measurements have already provided insight into a range of electrochemical processes such as underpotential deposition, adsorption of anions, hydrogen electroinsertion, etc… During electrochemical impedance experiments, the current response of a system to a perturbation (potential oscillation) is measured. By changing the frequency of the input signal, electrochemical processes with different time constants can be easily separated. Here the impedance technique was applied to the in situ stress measurements by measuring the variation in the stress of a gold cantilever in solution when applying a sinusoidal potential. Impedance measurements performed on a gold cantilever in HClO4 proved the feasibility of this new technique. This technique can also be applied during film growth, as demonstrated by the impedance measurements performed during the electrodeposition of Cu on an Au cantilever.