Surface Enhanced Raman Scattering Effect in Diamond Like Carbon Films Containing Ag Nanoparticles

In the present study surface enhanced Raman scattering (SERS) effect in hydrogenated diamond like carbon films containing Ag nanoparticles (DLC:Ag) deposited by reactive magnetron sputtering was investigated. The dependence of average diameter of the silver nanoparticle embedded into the diamond like carbon matrix as well as effective interparticle distance and amount of silver on SERS effect was experimentally investigated. It was demonstrated that combination of the larger size of the silver nanoparticles with lower effective interparticle distance is beneficial for appearance of the SERS effect in diamond like carbon films containing Ag nanoparticles. Appearance of the SERS related additional peaks in Raman scattering spectra of DLC:Ag films demonstrated dependence on the excitation wavelength as well as position of the plasmonic peak in the optical absorbance spectra of the films. Additional peaks along with D and G peaks (usually observed in Raman spectra of DLC films) appeared only when excitation wavelength was higher than position of the plasmonic absorption peak maximum. Number of the SERS related additional peaks and their intensity increased with the increase of the excitation wavelength used for the measurements of the Raman scattering spectra. Raman peaks related to vibrations of transpolyacetylene, benzene, polycyclic aromatic hydrocarbons as well as nanographite and silver oxide were identified in the investigated films.