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Structure modifications in materials irradiated by ultra-short pulses of VUV free electron laser

Jerzy B. Pełka 2Andrzej Andrejczuk 3Henryk Reniewicz 3Norbert Schell 4Jacek Krzywiński 2,5Ryszard Sobierajski 1Andrzej Wawro 2Zbigniew R. Zytkiewicz Dorota Klinger 2

1. Warsaw University of Technology, Faculty of Physics, Koszykowa 75, Warszawa 00-662, Poland
2. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland
3. University of Białystok, Institute of Experimental Physics, Lipowa 41, Białystok 15-424, Poland
4. ROBL-CRG at the ESRF, B.P. 220, Grenoble F-38043, France
5. Hamburger Synchrotronstrahlungslabor HASYLAB (HASYLAB), Notkestrasse 85, Hamburg D-22603, Germany

Abstract

The VUV TESLA FEL delivers radiation of peak power in the order of 1 GW in a short pulse of only 50-100 fsec. Such power levels are typical for laser ablation using conventional pulsed lasers. Theoretical predictions and very few experiments indicate that the behaviour of the solid matter under such conditions can differ substantially from that observed when the irradiation pulse durations are in the picosecond or nanosecond region. Investigation of the structure and microstructure of solids exposed to this type of irradiation is crucial to understand damage mechanisms in materials, and can imply also promising applications in various areas of nanotechnology.
The irradiation of various solids - insulators, semiconductors and metals has been carried-out with the quantum energy centered around 14 eV, in short pulses of only 80 fs and of peak power up to 1 GW. The FEL beam was focused on sample surfaces to microspots of size 10-100 mm. The energy density in the spots varied from below the ablation threshold ("annealing mode") up to far above this threshold ("damage mode"). The structural modifications induced with the irradiation was studied by a set of microscopic methods, the micro-Raman, as well as by the X-ray diffraction. AFM and Nomarski pictures illustrating variety of morphological structures created in the damaged areas will be shown. Especially promising seems to be a technique of recording the x-ray diffracted intensity distribution maps. We will show examples of the maps recorded on Si wafers around chosen spots. The maps determine the damage distribution range and intensity around the spots. The observed features are related to the FEL irradiation fluencies applied.

 

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Related papers

Presentation: poster at E-MRS Fall Meeting 2003, Symposium B, by Jerzy B. Pełka
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-07-25 17:40
Revised:   2009-06-08 12:55