Enhanced Raman spectroscopic study of interactions of tetracyanoethylene molecules with copper surfaces

Abstract

Abstract Tetracyanoethylene (TCNE) molecules chemisorbed on Cu electrodes for a wide range of applied potentials from −0.10 V to at least −1.60 V (vs. saturated calomel electrode). The molecules coordinated to the copper surface via the π-systems of both the CC and CN functional groups, downshifting the CC and CN stretching wavenumbers in excess of 100 cm−1. There was about 54% charge transfer between Cu and TCNE. Strong interactions with surfaces also lowered the site symmetry of the adsorbed molecules, inducing surface Raman modes, which were infrared active but Raman forbidden in the bulk phase. Reduction occurred at high cathodic potentials, and TCNE was probably reduced to the tricyanovinylalcoholate ion.