Sum-frequency generation spectra of thin organic films on silver enhanced due to surface plasmon excitation

We have studied vibrational spectra of thin films of copper phthalocyanine and fullerene of different thicknesses on silver obtained by a visible-infr ared sum-frequency generation (SFG). The free electron laser FELIX was used as a source of broadband infrared and the pulsed Nd:YLF laser system as a source of visible radiation. Excitation of a surface plasmon on silver has allowed to enhance the efficiency of the SFG process. The SFG signal has ap peared to be almost independent of the film thickness demonstrating the exc lusive contribution of the interfacial layer to the SFG signal.