Laser and Particle Beams



Nonequilibrium electron energy distribution in Au under subpicosecond laser irradiation: A kinetic study


S.  LONGO  a1, L.D.  PIETANZA  a1 c1, F.A.  TASSIELLI  a1 and M.  CAPITELLI  a1
a1 IMIP-CNR (Section of Bari) and Department of Chemistry, University of Bari, via Orabona 4, 70126 Bari, Italy

Abstract

We have performed a kinetic study of the electron dynamic relaxation inside a Au film subjected to a subpicosecond laser pulse. For this purpose, we have developed a time-dependent numerical solution of the Boltzmann equation for the electrons inside the film considering the collision integrals due to electron–electron and electron–phonon collisions and a perturbation term due to the laser pulse. Our results show that, after the pulse excitation, electron distributions are very far from equilibrium. Therefore it is not possible, especially in the first part of the temporal evolution, to describe the relaxation of the electron distribution through a two-temperature model.

(Received November 14 2001)
(Accepted December 30 2001)


Key Words: Boltzmann equation; Electron relaxation; Nonequilibrium electron energy distribution function; Subpicosecond laser irradiation; Two-temperature model.

Correspondence:
c1 Address correspondence and reprint requests to: Daniela Pietanza, IMIP-CNR (section of Bari) and Department of Chemistry, University of Bari, via Orabona 4, 70126 Bari, Italy. E-mail: pietanza@chimica.uniba.it