Intermolecular vibrational energy transfer between cyanide species at the platinum/electrolyte interface

A CN− adlayer on an electrochemical Pt surface produces two detectable vibrational bands. The band at 2160 cm−1 has previously been assigned to an intermediate species in the electrochemical production of [Pt(CN)4]2−. The second mode (≈2100–2140 cm−1) is attributed to a co-adsorbed cyanide monolayer. The lifetime of the 2160 cm−1 mode is ≈4–6 ps at potentials where the two modes are close in energy and approaches that of freely solvated cyanide ions (≈30 ps) at potentials where the two modes become well separated in energy. This potential dependence is interpreted in the context of a simple dipole–dipole coupling mechanism.