A three-dimensional thermal spike simulation of ultra-small Au nanoparticle embedded in silica surrounding

High electronic energy loss of swift heavy ions (SHIs) generates thermal spikes due to their passage through a material. The spatial and temporal evolution of the thermal spike within a metal nanoparticle (NP) embedded in dielectric surroundings can be evaluated using the three-dimensional thermal spike model (3DTSM). In this work, we have utilized this model to investigate the effect of 100 MeV Au ion on a 5 nm Au NP surrounded by silica matrix at two different ambient temperatures of 77 K and 300 K. The temperature evolution of electronic and lattice subsystems is reported. Our result shows that the radius of the ion track in silica is 7.3 nm and 7.8 nm for ambient temperatures of 77 K and 300 K respectively. The ion track form due to melting and subsequent re-solidification of the molten zone in a modified state. The lattice temperature of the Au NP increases by indirect heating as bulk Au is insensitive to thermal spike. The temperature of Au-silica interface increases initially and rapidly moves towards the center due to the high thermal conductivity of Au. The effect of ambient temperature on the evolution of thermal spike is found to be insignificant. Our simulation indicates the temperature of the NP surpasses the melting and vaporization temperature of gold which supports the mechanism proposed to describe experimental findings.