IMAGING AND SPECTRAL-ANALYSIS OF HYDROXYAPATITE LASER-ABLATION PLUMES

The images obtained during KrF excimer laser ablation of HA targets ha ve shown the presence of two different glow regions in the plume. The first one, plume-like shaped, expands at a velocity of about 2.0 x 10( 4) m/s. The second one, which looks like a small plasma cloud close to the target surface, shows an expansion velocity of about 2.9 x 10(3) m/s. The spectroscopic analysis of the plume has revealed the presence of several atomic (CaI, PI, OI, and impurities), ionic (CaII) and mol ecular (calcium oxides) species in the plasma. The dynamics of the mai n atomic and ionic species has been analysed from the spectra. CCD-ima ges recorded through diverse bandpass filters have been used to map th e species distribution along the plume and, thus, to identify the natu re of the previously observed glow regions. Pictures obtained by this method have revealed the atomic nature of the first glow region while the second one has been found to be mainly constituted by molecular ra dicals. (C) 1998 Elsevier Science B.V.