NEAR-INFRARED SURFACE-ENHANCED RAMAN-SCATTERING FROM METAL ISLAND FILMS

Surface-enhanced Raman scattering (SERS) of molecular species on metal island films of Au, and Au films roughened with underlayers of CaF2, was obtained using the near-infrared excitation line of the Nd:YAG laser at 1.064-mu-m. The molecular species were vanadylphthalocyanine and 3,4,9,10-perylenetetracarboxylic dianhydride, which were coated onto the Au surfaces as thin vacuum-evaporated layers. An enhancement factor of about 100 was obtained for the electromagnetic enhancement. Demonstration of the infrared SERS effect for the two macrocycle molecules is presented and comparisons are made with previous SERS results obtained with visible light excitation. This is the first reported observation of SERS from metal island films with excitation in the infrared region.