Photoemission from localized surface plasmons in fractal metal nanostructures

We use photoemission microscopy to characterize localized surface plasmon distributions in nanostructured gold layers on indium-tin-oxide/glass substrates. The Au films have a fractal dimension of similar to 1.3 and smallest feature sizes of similar to 100 nm. We use femtosecond laser pulses at a wavelength of similar to 800 nm for the plasmon excitation. Photoelectron emission occurs by a three-photon process in localized areas of indium-tin-oxide with similar to 70 nm diameter. In these areas the photoemission rate is enhanced several thousand fold compared to nonstructured surface areas. The results show that plasmon enhanced photoemission can be induced in a nonabsorbing material in proximity to a plasmon-active metal nanostructure. (C) 2010 American Institute of Physics. [doi:10.1063/1.3457921]