Seminars Archive

Experiments with Highly Charged Ions and Free Electron Laser Light

Abstract
The interaction of Highly Charged Ions (HCIs) with surfaces is of primary importance for understanding the formation of objects such as the hollow atoms, their stabilization and relaxation. Because of the large amount of potential energy that these ions carry with respect to their kinetic energy, such investigations attract continuous interest, for example - the use of HCIs in techniques of surface modification or analysis, and more in general - in nanotechnology application. The studies were performed at the Manne Siegbahn Laboratory in Stockholm. The highly charged lead ions were produced in the CRYSIS ion source [1] and were directed on metal foils. A technique based on coincidence measurement of two x-ray photons escaping from the front and back sides of the foil was developed. The method directly provides the mean x-ray emission depth and a possibility to determine the mean relaxation time of the hollow atoms [2]. - The Elettra Storage-Ring Free-Electron Laser (FEL) as a test-facility for the generation of coherent sub-ps radiation. After successful experiments using the FEL light in an oscillator configuration the present activity of the FEL group at Elettra is currently concentrated on single-pass Coherent Harmonic Generation (CHG). For this purpose, the standard configuration of the FEL has been modified and use is made of an external seed laser. Seeded schemes represent nowadays the only valuable alternative to Self-Amplified Spontaneous-Emission (SASE) for obtaining intense, tunable, short-pulse radiation in the region from the deep ultraviolet down to x-rays wavelengths. First results are summarized. [1] E. Beebe, L. Ljiljeby, A. A. Engstrom, and M. Bjorkhage, Phys. Scr. 47, 470 (1993); http://www.msl.se/ANNREP/AR00.pdf; http://www.msi.se/crysis/CRYSIS.HTM [2] Z. D. Pesic, Gy. Vikor, S. Atanassova, J. Anton, S. Leontein, M. Bjorkhage, A. Paál, H. Hanafy, R. Schuch, “Relaxation of slow highly charged ions hitting thin metallic foils‿, Phys. Rev. A, 75, 012903 (2007)