Europhys. Lett.
Volume 67, Number 3, August 2004
Page(s) 404 - 410
Section Physics of gases, plasmas and electric discharges
Published online 01 July 2004
Europhys. Lett., 67 (3), pp. 404-410 (2004)
DOI: 10.1209/epl/i2004-10080-2

Emission of nanoparticles during ultrashort laser irradiation of silicon targets

S. Amoruso, R. Bruzzese, N. Spinelli, R. Velotta, M. Vitiello and X. Wang

Coherentia - INFM and Dipartimento di Scienze Fisiche Università di Napoli Federico II, Complesso Universitario di Monte S. Angelo Via Cintia, I-80126 Napoli, Italy

(Received 6 April 2004; accepted in final form 25 May 2004)

We have experimentally observed that nanoparticles emission is a peculiar feature of matter removal during ultrashort (fs) laser pulse irradiation of silicon followed by vacuum expansion. Time-resolved optical emission spectroscopy has been used to characterize the plume expansion dynamics, while atomic force microscopy analysis of silicon nanoparticles deposited after 100 $\un{fs}$ laser ablation has shown an average particle size of $\approx 7$ $\un{nm}$, with a pretty narrow size distribution. This is in agreement with the predictions of recent theoretical models on the mechanisms underlying ablation of solids in this ultrashort temporal regime. Finally, a phenomenological model of nanoparticles cooling during their vacuum expansion has allowed us to single out radiative cooling as the most effective cooling mechanism in the late stage of plume expansion.

52.38.Mf - Laser ablation.
79.20.Ds - Laser-beam impact phenomena.

© EDP Sciences 2004