Atomic clusters of various sizes irradiated with short intense pulses of VUV radiation

¹  Hamburger Synchrotronstrahlungslabor, Deutsches Elektronen-Synchrotron - Notkestr. 85, D-22603 Hamburg, Germany, EU
²  Department of Theoretical Physics, Institute of Nuclear Physics - Radzikowskiego 152, 31-342 Cracow, Poland, EU
³  Technische Universität Berlin, Institut für Optik und Atomare Physik - Hardenbergstrasse 36, D-10623 Berlin, Germany, EU

Corresponding author: ziaja@mail.desy.de

Received: 7 December 2007
Accepted: 29 February 2008

Abstract

Non-equilibrium processes following the irradiation of atomic clusters with short pulses of vacuum ultraviolet radiation are modelled using kinetic Boltzmann equations. The dependence of the ionization dynamics on the cluster size is investigated. The predictions on: i) the maximal and average ion charge created, ii) ion charge state distribution, iii) average kinetic energy per ion, iv) spatial charge distribution, and v) thermalization scales are obtained for spherical xenon clusters containing 20, 70, 2500 and 90000 atoms. These clusters were exposed to single rectangular pulses of vacuum ultraviolet radiation of various pulse intensities, I~ 10¹²- 10¹⁴ W/cm² and durations, 50 fs, at a fixed integrated radiation flux of F≡ I = 0.4 J/cm². The results obtained are found to be in good agreement with the available experimental data, especially the dependence on the cluster size, if it is assumed that the ions from the positively charged outer layer of the cluster constitute the dominant contribution to the experimentally measured ion charge state distribution.