Electrochemical modulation for signal discrimination in surface enhanced Raman scattering (SERS).

Electrochemical modulation to induce controlled fluctuations in SERS signals is introduced as a method to discriminate and isolate different contributions to the spectra. The modulation--which can be changed in potential range, amplitude, and frequency--acts as a controllable "switch" to turn on, off, or change specific Raman signals which can then be correlated within the spectra by different fluctuation analysis techniques. Principal component analysis (PCA), either by itself or assisted by fast fourier transform (FFT) prefiltering, are shown to provide viable tools to isolate the different components of the spectra. Electrochemical modulation provides, therefore, a technique to study complex cases of coadsorption, and resolve problems of spectral congestion in SERS signals.