Spectral and Temperature Dynamics of the Processes inside Aqueous Droplets Containing Eosine Molecules and Silver Nanoparticles upon Laser Excitation in the IR and Visible Ranges

Abstract

Photophysical and thermal processes in a droplet of an aqueous solution of eosine with silver nanoparticles (NPs) produced by laser ablation are studied upon double laser excitation, stationary (λ = 532 nm) and IR pulsed (λ = 10.6 μm). It is established that after IR exposure, long-lived luminescence is generated due to intercombination transitions inside molecules, the intensity of which depends on the concentration of eosine and NPs, and the coordinates of the region of luminescence glow in a microvolume of the droplet. The processes of thermal diffusivity and thermal conductivity after exposing a drop of the solution to IR radiation are modeled. The effect the surface plasmons of silver NPs have on the efficiency of quenching the thermally activated luminescence (TL) of a droplet is determined, the rate constant of which is equal to the constant of diffusion.