Hybrid gold-silver nanoparticles synthesis on a glass substrate using a nanosecond laser-induced dewetting of thin bimetallic films and their application in SERS

Generation of hybrid gold-silver nanoparticles from different metal ratios by thermal heating thin metal films on a glass surface with a nanosecond pulsed laser is presented. The optical properties of obtained nanoparticles are dependent on localized surface plasmon resonance (LSPR), which can be tuned in the range of 400-530 nm by varying the ratio and order of the primary films. The LSPR's width ranges from 40 nm to 130 nm. The various resonance widths suggest that different types of nanoparticles (monometallic or bimetallic alloy) with various concentrations and size distributions can be produced by laser-induced dewetting of thin bimetallic films. Substrates with engineered nanoparticles can act as SERS substrates with a high enhancement factor (more than 105) using different excitation wavelengths (532 and 633 nm). The best results in SERS experiments were obtained using a 532 nm excitation line. The enhancement factor directly depends on the size of the prepared nanoparticles. The demonstrated laser-based process for large-scale production of SERS substrates is ordinary, reliable, chemical-free, and cost-effective.