Expansion dynamics of Bi atoms produced by laser ablation of Bi and BGO targets

A comparative study of the expansion dynamics of the Bi species present in the plasma produced by laser ablation of Bi12GeO20 and Bi targets is carried out in vacuum by spatially-resolved real-time emission spectroscopy. The emission spectrum from the BGO target mainly shows the presence of neutral Bi).and single ionised Biq). Bi species. Two populations of Bi) species are observed. The first one dominates the emission close to the target surface 0FdF4 mm.at short times after the laser pulse; while the second population becomes dominant at distances dG6 mm and lasts much longer t)5 ms.. Such second population is not observed in the case of either the ionised species or any of the excited species present in the plasma generated by ablation of the Bi target. The existence of complex molecules in the plasma generated by ablation of BGO targets, which dissociate during the expansion, is proposed as the mechanism responsible for the appearance of the delayed Bi) population. q1999 Elsevier Science B.V. All rights reserved.