Laser and Particle Beams


Ultrafast electron relaxation measurements on [alpha]-SiO2 using high-order harmonics generation

H.  MERDJI a1c1, S.  GUIZARD a2, P.  MARTIN a2, G.  PETITE a2, F.  QUÉRÉ a2, B.  CARRÉ a1, J.F.  HERGOTT a1, L.  LE DÉROFF a1, P.  SALIÈRES a1, O.  GOBERT a1, P.  MEYNADIER a1 and M.  PERDRIX a1
a1 Service des Photons, Atomes et Molécules, DSM-DRECAM, CEA Saclay, 91191 Gif-sur-Yvette, France
a2 Service de Recherche sur les Surfaces et l'Irradiation de la Matière, DSM-DRECAM, CEA Saclay, 91191 Gif-sur-Yvette, France


Time-resolved photoemission spectroscopy, using high order harmonics, is used to measure the energy relaxation rate of hot electrons in [alpha]-SiO2 with sub-picosecond time resolution. Our results indicate that electrons of 30 eV kinetic energy in the conduction band relax at a rate which is at least two orders of magnitude lower than the one of photo-excited carriers of a few eV. As a result, we give insight in the relaxation process of hot electrons and show that impact ionization probability per unit time is only of the order of 1/40 ps−1, in very strong contrast with the much higher value generally assumed in models of optical breakdown.

(Received August 27 1999)
(Accepted October 14 1999)

c1 Address correspondence and reprint requests to: H. Merdji, CEA, Service des Photons, Atomes et Molecules, Bat. 524, Centre d'Etudes de Saclay, 91191 Gif-sur-Yvette Cedex, France. E-mail: