Formation Conditions and Morphology of Nanoscale Features on the Surfaces of Metals and Alloys under Femtosecond Laser Treatment

Abstract

Surface texturing of metals and alloys with Ti: Sapphire femtosecond laser has been carried out in air. The peculiarities of surface patterns formed on the surface of noble metals (silver, gold, copper), refractory metal (tungsten) and metal-semiconductor alloy under ultrashort laser pulses have been studied by means of the surface morphology analysis. The influence of the laser ablation process on the formation of nanoscale features on the laser treated surfaces has been discussed. In the experiments, the low fluence multi-pulse regime near the ablation threshold for studied materials has been realized. The average sizes of nanoscale features formed under ultrashort laser processing on the surface structures have been determined for silver, gold, copper and tungsten. Observed enhancement of Raman signal for some vibrations of Methylene Blue dye adsorbed on laser-induced Ag surface structures demonstrates the possibility of an application of the laser-textured substrates as surface enhanced Raman scattering (SERS) substrates used for biosensing.