The Detection Capabilities of Fourier Transform External Reflection and Photoacoustic Spectroscopy for Electrode-Supported Films

Abstract

Fourier transform infrared external reflection and photoacoustic spectroscopy has been used for the vibrational characterization of a Prussian Blue (PB) film on Pt and a cupric hexacyanoferrate (CuHCF) film on glassy carbon (GC) irradiated at normal incidence. Since the optical response appeared to be substrate dependent, the mean-square electric fields as a function of the optical constants of the substrates (Pt, GC) and the films (PB, CuHCF) were calculated. The results of these calculations, used with the experimentally determined signal-to-noise ratios, were employed to predict film detection limits. It was found that the electric field intensity near the CuHCF/GC interface was much greater than that near the PB/Pt interface. For this reason, the film thicknesses detectable by these spectroscopic methods are lower at the interface of the GC substrate than at the Pt substrate.