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International Journal of Photoenergy
Volume 3 (2001), Issue 3, Pages 123-129
http://dx.doi.org/10.1155/S1110662X01000149

Laser induced desorption and ablation: mechanism of metal removal from an Al-Cu-Fe alloy and a quasicrystal of the same composition

1Dipartimento di Chimica, Università “La Sapienza”, Piazzale A. Moro 5, Rome 00185, Italy
2Lawrence Berkeley National Laboratory Berkeley, California 94720, USA
3Istituto Materiali Speciali, CNR, Via Loja, Tito Scalo (PZ), 85050, Italy

Copyright © 2001 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Quasicrystals are a special class of metallic alloys that share some of the properties of crystals. Their structures reduce to a single repeating unit like that of the unit cell of a crystal. The quasi-unitcell is representative of a cluster like structure where electrons cannot move with freedom as in metals. Quasicrystals are formed of metallicelements but they do not have metallic properties.

The diversity of the fractionation behavior induced by laser desorption and ablation of the Al70Cu20Fe10 of the intermetallicalloy and of the Al65Cu23Fe12 quasicrystal has been examined in terms of the structural properties of the two compounds. Elemental fractionation during laser desorption and ablation sampling was investigated by using inductively coupled plasma mass spectrometry. The experiments were carried out in two different irradiance regimes by a Nd-YAG laser with 266 nm wavelength and single 6 nanosecond laser pulses. In the high irradiance regime (>0.04, 0.07GW/cm2) the effect of the laser irradiance is not discriminating. In the low irradiance regime (<0.04, 0.07GW/cm2) large differences have been found between the alloy and the quasicrystal. The results have been interpreted on the basis of a thermodynamic vaporization process for the intermetallic alloy. An electronic model of localized excitation is suggested for the physical process of surface material removal from a quasicrystal.