Comparative time-resolved study of solid-state and liquid ablation of polyethylene-glycol 1000: temperature, viscosity and surface tension dependence

Comparative study of solid and liquid phase ablation on the same sample by time-resolved investigations is presented in this paper. Polyethylene-glyco l (PEG) 1000 having relatively low melting point (35 degrees C) was used in our experiments. By varying the sample temperature in the 20-80 degrees C range we could study the ablation mechanism in both solid and liquid (below and above the melting point) state of matter. An ArF excimer laser (lambda = 193 nm, FWHM = 20 ns) was used for ablation at 1.95 J/cm(2) fluence. Abl ation processes were observed by transmission fast photographic arrangement . It was demonstrated that plasma development and expansion (primer ablatio n, in 0-50 ns time range), formation and propagation parameters of shock wa ve and contact front did not depend on sample temperature and state of matt er. The secondary material ejection (between 1-100 mu s) showed a strong te mperature dependence. Material ejection in the case of solid target occurre d in the form of dense material cloud. and in the form of splashing for liq uid (molten) sample. The ejection velocity of splashed jets depended on the sample temperature, significantly. This can be due to the change of molten PEG 1000 viscosity.