SURFACE THERMAL-EXPANSION OF METAL UNDER FEMTOSECOND LASER IRRADIATION

Transient surface displacement of gold under femtosecond laser irradia tion is studied using a probe beam deflection technique. A surface the rmal expansion rise time of about 100 ps is explained in terms of none quilibrium diffusion and thermalization of photoexcited electrons. Tra nsient displacement provides direct information on the lattice tempera ture profile established once the electron-lattice relaxation is compl eted. (C) 1997 American Institute of Physics.