W0210

Transient Structures by Means of Time Resolved X-ray Diffraction and EXAFS of Solids and Liquids. V. Tomov, D.A. Oulianov, A.S. Dvornikov, P.M. Rentzepis, Dept. of Chemistry, Univ. of California, Irvine, CA 92697.

We have measured picosecond and nanosecond transient structures of solids by means of time resolved x-ray diffraction. Similar experiments have been performed in the liquid phase utilizing a new EXAFS experimental system capable of subpicosecond resolution.

The experimental systems utilized for the determination of the transient structures consist of: a) An x-ray diode that is pumped by a 10 picosecond ArF 190nm, 300Hz excimer laser that generates electrons which are accelerated onto a metal Cu, W, or Mo cathode producing characteristic line and continuum picosecond x-ray pulses. b) A new experimental system produces 1 ps or less hard x-rays by focusing the output of a Ti:saph. laser, 150fs, 200 mJ per pulse, onto a 20 micron area of a Cu or W wire. The x-ray output is focused onto the sample by means of a capillary x-ray lens that increases the x-ray flux by approximately three orders of magnitude. Time resolved x-ray diffraction and EXAFS experiments will be presented and the possibility of measuring transient structures with femtosecond resolution will be discussed.