Composition and structure characterization of aluminum after laser ablation

The process of laser ablation of an aluminum surface with copper bromide laser (511 nm) was investigated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), with the laser fluence varying from 5.3 to 11.1 J/cm2 and the laser beam scanning velocity from 20 to 100 mm/s. The experiments were done in two kinds of ambient atmosphere: air and argon. SEM analysis showed the porous structure of the laser treated surface and formation of micro- and nano-sized particles. The dimensions of the agglomerates formed were smaller in argon atmosphere. Upon irradiation in Ar atmosphere the aluminum nanoparticles were formed in a metal state and their surface was oxidized after exposure to O2 in air. However, two mechanisms are possible in air, the first one being the same as under Ar and the second occurring direct in the plasma. The binding energies of the Al 2p (74.0 eV) and O 1s (531.4 eV) peaks and the O/Al ratio give information on the oxidation of the surface and presence of aluminum in Al2O3 and AlOOH. The oxide layer was porous, which was evidenced by SEM.