Energy distributions in the laser ablation of metals and polymers

Time-of-flight TOF.mass spectrometry has been used to investigate the mass distribution of the material ablated from the interaction of a UV laser FWHMs30 ns, ls308 nm.with aluminum, copper, and polyimide at laser intensities of 3.8=1012–1.0=1013 W my2. High energy 10–152 eV.neutral particle emission was observed for all three materials. This is believed to be due to the formation of clusters in the laser-induced plasma which subsequently undergo rapid ionization -1 ps.. The ions generated in the clusters are then subject to explosive expansion due to Coulomb repulsion and electron pressure. Modeling of the cluster ionization process reveals that ions with energies )100 eV can be produced by this process. q1998 Elsevier Science B.V.