Picosecond-laser-pulse-induced heat and mass transfer

The interaction of picosecond and sub-picosecond laser pulses with metals is investigated both, theoretically and experimentally. Analyzing the Boltzmann equation for electrons and phonons the hyperbolic two-temperature model of heat conduction in metals is obtained. In particular the parameter range for which the hyperbolic effects are significant is analyzed. For calculations a numerical algorithm based on the method of lines is developed. Experimentally laser pulses with a duration of 40 ps are used to remove thin metal films. The removal process is analyzed by pump and probe measurements with the time resolution of 40 ps. The single-shot removal threshold and the removal rate per pulse are determined for copper. By this technique the existence and the propagation of shock waves in the ambient atmosphere induced by the removal process are detected. Theoretical calculations are compared with experiments and the results from the literature.