title: Contribution of material's surface layer on charge state distribution in laser ablation plasma.
abstract: To generate laser ablation plasma, a pulse laser is focused onto a solid target making a crater on the surface. However, not all the evaporated material is efficiently converted to hot plasma. Some portion of the evaporated material could be turned to low temperature plasma or just vapor. To investigate the mechanism, we prepared an aluminum target coated by thin carbon layers. Then, we measured the ablation plasma properties with different carbon thicknesses on the aluminum plate. The results showed that C(6+) ions were generated only from the surface layer. The deep layers (over 250 nm from the surface) did not provide high charge state ions. On the other hand, low charge state ions were mainly produced by the deeper layers of the target. Atoms deeper than 1000 nm did not contribute to the ablation plasma formation.
authors.affiliation: Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kumaki
authors.affiliation: Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Dannie
authors.initials: D
authors.lastname: Steski
authors.affiliation: Nishina Center for Accelerator-Based Science, RIKEN, Saitama 351-0198, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Ikeda
authors.affiliation: Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kanesue
authors.affiliation: Nishina Center for Accelerator-Based Science, RIKEN, Saitama 351-0198, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Okamura
authors.affiliation: Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Washio