Diffuse reflectance spectroelectrochemistry as a probe of the chemically derivatized electrode interface. The derivatized nickel electrode

Diffuse reflectance spectroelectrochemistry has been employed to directly monitor the interface charge-transfer (CT) behavior of surface-bound [Ni^II(NC)Fe^II/III(CN)₅]^2-/- on a nickel electrode. The technique is shown to be species specific and sensitive to the amount of surface-confined material and the oxidation state of the surface-attached species. It is therefore of utility in observing the time-dependent behavior of the surface species under transient potential conditions. This technique is compared with chronocoulometry carried out on the same system. The two techniques are used to obtain values of apparent diffusion coefficients for the derivatized surface. In the short-time limit both techniques are shown to follow the Cottrell equation. However, it is necessary to incorporate time-dependent diffusion coefficients to obtain agreement for long-time data. The reflectance technique is shown to be superior to chronocoulometry in that it can discriminate against current not associated with the surface species of interest.