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We present theoretical results on the near field distribution in the vicinity of gold particles excited by laser radiation and placed on various substrate materials. The study is directed towards the precise nanostructuring of different material surfaces. The calculations are performed on the basis of the FDTD simulation technique. Metal (Au), semiconductor (Si) and dielectric (SiO2) substrate materials are investigated. Experimental results are shown to confirm the validity of the obtained FDTD simulation results. The results show that the field in the vicinity of the point of contact is enhanced, and the enhancement factor depends on the substrate material, particle size and the wavelength of the incident optical radiation. The characteristic size of the field enhanced area is found to be several times smaller than the gold particle size: for the case of the smallest particle diameter of 40 nm it is about 10 nm. The enhancement factor of the electric field on the substrate surface is highest when the substrate is gold metal and it decreases about two orders of magnitude when dielectric SiO2 substrate is used. The characteristic penetration depth of the enhanced field is within several tens of nanometres and the depth weakly depends on the substrate material and the laser excitation wavelength. The dependence of the gold particle size on the field enhancement factor is investigated as well. The present results can be used to predict and design precise nanostructuring on different materials with gold nanoparticles excited by a femtosecond laser pulse.

ZnO nanorod arrays on Si (1 0 0) substrate were grown by the pulsed laser deposition (PLD) method, and then coated with Au. Two samples of Au-coated nanorod arrays with different average diameters of 150 and 400 nm were prepared to investigate the size dependence of the surface enhanced Raman scattering (SERS). The diameter of the nanorods was controllable by the substrate position during PLD. High SERS enhancement was observed from both Au-coated ZnO nanorod arrays. The Raman spectra of rhodamine 6G (R6G) as low as 1 nM were measured with an average diameter of 400 nm at an excitation wavelength of 532 nm. The SERS was explained by the field enhancement effect induced by surface plasmon polaritons of Au-coated nanorods (nanoshells).