Ultrafast thermal melting of laser-excited solids by homogeneous nucleation

Homogeneous nucleation is considered as a mechanism for rapid thermal melting of solids irradiated with ultrashort laser pulses. Based on classical nucleation theory we show that for sufficient superheating of the solid phase the dynamics of melting is mainly determined by the electron-lattice equilibration rather than by nucleation kinetics. Therefore, complete melting of the excited material volume should occur within a few picoseconds. This time scale lies between the longer time scale for heterogeneous, surface-nucleated melting and the shorter time scale for possible nonthermal melting mechanisms.