Fluctuations of Raman spectra of hydrogenated amorphous carbon deposited on electrochemically-roughened silver

Various deposits of hydrogenated amorphous carbon (a-C:H) on silver have been studied with surface-enhanced Raman scattering (SERS). When short accumulation time was used and scattered radiation were recorded with a Raman microscope, subsequently measured spectra of a-C:H often exhibited strong fluctuations. We showed by analysing the spectral fluctuations for various a-C:H samples, that the process leading to the appearance of strong SERS fluctuations is practically insensitive to the actual structure of a-C:H clusters. The appearance of strong SERS fluctuations should be, therefore, explained by the temporal changes of the electromagnetic enhancement, rather than by the fluctuations of the resonance enhancement.