Laser melting and evaporation of nanoparticles: A simplified model for estimations of threshold fluence

Theoretical investigations and estimations of laser threshold fluencies are carried out for melting and evaporation of solid spherical nanoparticles by laser pulses in a liquid medium. Simple analytical model has been developed for this purpose. The temporal dependencies of nanoparticle temperature and conservation energy law are used for estimations of threshold laser fluencies. The analytical dependencies of threshold fluencies on pulse durations, laser wavelengths and nanoparticle radii are established and discussed. Comparison of some predicted values of the threshold laser fluencies for melting and evaporation of gold spherical nanoparticle in water with experimental data is given and satisfactory agreement of these results validates the model developed. Estimation of maximal nanoparticle temperature at the end of laser action on nanoparticle can provide the determination of realized processes and necessary checking and validation of experimental data. These model and results can be used for the thermal processes of nanoparticle treatment and applications in various laser technologies.