Laser assisted blending of Ag nanoparticles in an alumina veil: a highly fluorescent hybrid

Abstract

We report a functional hybrid made of silver nanoparticles (AgNPs) embedded in an amorphous aluminium oxide (alumina) film. This laser-initiated process allows formation of AgNPs and amorphous alumina in localized regions defined by the scanning laser beam. Due to metal enhanced fluorescence, this hybrid exhibits strong blue fluorescence emission under ultraviolet excitation. Upon irradiating with electrons at dosages of 1 to 20 mC cm⁻², AgNPs become more metallic while the Al film is further oxidised. As a result, the fluorescing property is intensified. Using a hybrid irradiated with 10 mC cm⁻², the electronic conductivity of the sample is improved by 11.5 times compared to that of the as-synthesized hybrid film. Excitation by UV light on the sample results in an increase in the detected current of nearly 29 times. Given that the electron beam patterned message is selectively visible only under UV or blue light irradiation, this hybrid film is thus a possible platform for steganographic transmission.