Surface-Enhanced Raman Scattering at the Silver Electrode/Ionic Liquid (BMIPF6) Interface

This is the first report of in situ SER spectra of chemical species adsorbed on a Ag/room temperature ionic liquid (RTIL) interface. We have investigated the dependence of the SERS intensity of the RTIL derived from 1-n-butyl-3-methylimidazolium hexafluorophosfate (BMIPF6) adsorbed on a silver electrode. It has been shown that the BMI+ adsorbs on the silver electrode for potentials more negative than −0.4 V vs a Pt quasireference electrode (PQRE). In the −0.4 to −1.0 V potential range the SER spectra are similar to the Raman spectrum of the RTIL BMIPF6. At potentials more negative than −1.0 V some imidazolium ring vibrational modes and N−CH3 vibrations are enhanced, suggesting that the imidazolium ring is parallel to the surface and for potentials