Abstract

The relaxation dynamics of laser-heated electrons has been studied extensively in metals and (hiTc) superconductors[1] by various femtosecond thermomodulation techniques. These measurements give new insights in the electronic properties and provide direct information about the electron-phonon (e-p) coupling strength. A nearly unexplored type of dynamics is the (e-e) dynamics within the electron gas in a laser-heated metal. The extremely small e-e collision time (~ 10 fs), associated with the highly nonthermal electron distribution during excitation, makes direct observation a challenging task. We report the first experimental evidence of e-e dynamics in thermoreflection measurements by its direct effect on the e-p energy relaxation process for Ag and Au in the regime of low temperature and low laser-energy density[2]. The well-established two-temperature model cannot account for our results and a new model has been succesfully applied.

© 1992 The Author(s)