Inductively coupled plasma mass spectrometric study of laser sputtering from the surface of an Al-Cu-Fe alloy and quasicrystal

The fractionation behavior induced by laser desorption and ablation of the Al₇₀Cu₂₀Fe₁₀ intermetallic alloy 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 power density regimes by using a Nd-YAG laser with 266 nm wavelength and single 6 ns laser pulses. In the high power density regime (>0.04–0.07 GW/cm²) the effect of the laser power density on ablation behavior was similar for the two materials. In the low power density regime (<0.04–0.07 GW/cm²) large differences have been found between the alloy and the quasicrystal. The results are 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.