Interface kinetics during pulsed laser ablation

Abstract

This work investigates evaporation kinetics — the relation between the surface temperature and pressure during excimer laser ablation. Nickel targets are ablated by excimer laser pulses in a laser fluence range between 1 and 6 J/cm2, with the upper limit exceeding the threshold of phase explosion (5 J/cm2). The surface pressure is determined with a polyvinylidene fluoride (PVDF) piezoelectric transducer. When phase explosion occurs, the surface temperature is known to be near the thermodynamic critical temperature, therefore, by measuring the surface pressure, the surface temperature-pressure relation is determined at the threshold fluence of phase explosion. The surface temperature and the threshold fluence of phase explosion are also estimated from the measured velocity of the vapor plume and gas dynamics calculations. It is shown that, during excimer laser ablation, the temperature and pressure relation deviates significantly from the equilibrium kinetic relation.