Laser induced desorption and ablation: mechanism of metal removal from an Al-Cu-Fe alloy and a quasicrystal of the same composition
Mauro Satta,1Haichen Liu,2Xianglei Mao,2Giuliano Moretti,1Richard E. Russo,2Anna Giardini,1,3and Aldo Mele1
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.