Ultraviolet pulsed laser interference lithography and application of periodic structured Ag-nanoparticle films for surface-enhanced Raman spectroscopy

Ag-nanoparticle films were deposited on glass and silicon substrates by evaporation of a colloidal solution. Periodic structures were created in these Ag nanoparticle deposits by ultraviolet nanosecond laser interference lithography (LIL). We find that the periodic structure and size of Ag nanoparticles in these oriented arrays can be controlled by varying laser pulse energy as well as the number of pulses used in irradiation. The effect of these parameters on the overall morphology of these deposits is shown to be promising as a new technique for the engineering of sub-micron nanoparticle structures. Ag films with laser-induced sub-micron periodic structures were evaluated as substrates for surface-enhanced Raman spectroscopy using rhodamine B adsorbed from a 10(-8) M solution. Enhancement factors were found to be >10(6) those found in conventional Raman scattering and 10 times greater than those from standard Ag-nanoparticle films. These results indicate that the LIL method has promise in the nanostructuring of Ag-nanoparticle films for ultrasensitive SERS biosensing substrates.