Berlin 2001 – scientific programme

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Q: Quantenoptik

Q 23: Poster: Application of Short Pulses

Q 23.4: Poster

Thursday, April 5, 2001, 12:30–15:00, AT2

Set-up for ultrafast time-resolved x-ray diffraction using a femtosecond laser-plasma keV x-ray source — •C. Blome, K. Sokolowski-Tinten, C. Dietrich, A. Tarasevitch, and D. von der Linde — Institute for Laser- and Plasmaphysics, University of Essen, Universitätsstr. 5, 45117 Essen, Germany

We describe a set-up for ultrafast time resolved x-ray diffraction experiments, which is based on a short-pulse 4.51 keV titanium Kα femtosecond laser-plasma x-ray source. To generate the x-rays terawatt laser pulses (120fs, up to 150 mJ) are focused onto the surface of a 250µm thick titanium wire which is continously moved through the focus of the laser. This target design is very compact which simplifies radiation protection issues and allows virtually infinite measurement times. We present a detailed characterization of the source and discuss experiments aimed to optimize our source for ultrafast time resolved x-ray diffraction experiments. To increase the usable Kα-flux the source is imaged onto the surface of the specimen under study with the help of a toroidally bent crystal mirror. Optical pump, x-ray probe experiments at laser-excited semiconductor surfaces reveal an upper limit for the x-ray pulse duration at 4.51keV of about 500fs.