Reduction of the effect of electron relaxation behavior on the femtosecond laser-induced response of copper thin film by ballistic energy transfer

The thermomechanical response of a copper thin film to ultrafast laser with the pulse durations from 10 to 100 fs is investigated by the methods integrating the parabolic and hyperbolic two-temperature models with the molecular dynamics. It is found that there is an insignificant discrepancy in the results obtained by the two different two-temperature models for all the considered pulse durations, indicating the trivial effect of electron relaxation behavior on the response of the heated copper film. Further study suggests that the electron relaxation effect on the material response could be offset by the energy transport due to the ballistic electron motion.