Particle–metal interactions. A raman and electrochemical study of a compacted electrode of copper phthalocyanine and silver metal

Abstract

Electrodes consisting of a compacted mixture of powders of silver metal and α copper phthalocyanine (CuPc) have been used to study the interaction between small pigment particles and a metal surface using resonance Raman spectroscopy as a probe of in situ changes. The purpose of this present paper is to explore the condition required to produce optimum enhancement.Cycling in acid sulphate or nitrate electrolytes with a sufficiently positive voltage to release silver(I) ions resulted in the formation of a thin layer of CuPc particles spread out on the metal surface. The layer formed produced an improvement in Raman scattering from CuPc. From the resonance profile it was clear that there was a significant charge transfer interaction with the metal surface. The relative intensities of the peaks in the Raman spectra are dependent on potential. As well as the possible use of such electrodes in chemistry, particle metal layers of this type provide a different starting point for studies of the surface enhanced resonance Raman effect emphasising the electromagnetic contribution rather than the chemical one.