Comparison of optical and structural properties and stability of copper-silver and copper-gold surface nanostructures fabricated by laser irradiation

In this paper, copper-gold and copper-silver bimetallic surface nanospheres were formed using ArF excimer laser irradiation with a wavelength of 193 nm and a duration of 15 ns on thin film samples consisting of two metal layers deposited on BK7 glass. The density and shape of the structures were obtained under different irradiation conditions. The optical properties, morphology, and stability of optimal copper-gold and copper-silver structures were compared. The results show that high-density copper-gold core-shell nanospheres with high optical response and stability are produced at a fluence of 150 mJ/cm2 and 5 laser pulses. Silver-copper nanostructures showed lower density, weaker optical response, and lower stability than other nanostructures. The obtained copper-gold nanostructures are suitable for use in plasmonic applications such as biosensors and surface-enhanced Raman spectroscopy.