Abstract

It has recently been demonstrated that strongly nonequilibrium excitation can be induced in a metal irradiated by a femtosecond laser pulse.¹ The laser energy is initially absorbed as electronic excitation, which rapidly thermalizes. Only on the scale of a hundreds of femtoseconds is energy transferred to lattice vibrations of the metal. Thus, one may describe the solid by separate electronic (T_e) and lattice (T_l) temperatures. Because of the lower heat capacity of the electrons, the peak electronic temperature rises to a much higher value than the lattice temperature. This observation suggests that nonequilibrium electronic excitation induced by femtosecond laser pulses may give rise to distinctive new physical processes at the surface of a metal. In this paper, we report results concerning molecular desorption of NO from a Pd(111) surface under irradiation by 616-nm laser pulses of 200-fs duration.

© 1990 Optical Society of America