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Press Release

October, 23th, 2002

First direct measurement of the decay of a hole in the atomic shel


A german-austrian collaboration of scientists of the University of Bielefeld and of the Technical University in Vienna succeded in measuring for the first time the temporal evolution of the rearrangement of the electron cloud of an atom after excitation with an ultrashort X-ray pulse.

If ionizing radiation creates a hole in an atomic shell a new balance is reached by redistribution of the remaining electrons. The electrons emitted during this process are known to play an important role e.g. in the radiation damage of biological tissues. Compared to most processes induced with visible light, this relaxation occurs on a much faster time-scale and was therefore not accessible to a time-resolved measurement. The physicist Markus Drescher (Photo) from Bielefeld now reports in the October, 24th issue of 'Nature' on the application of a novel source for extremely short attosecond (1 as = 10-18s) X-ray pulses for this purpose. These shortest electromagnetic light pulses were developed in cooperation with the team of Ferenc Krausz at the TU Vienna. The key-technology for producing the neccessary dedicated X-ray optics was contributed by Ulrich Heinzmann and coworkers from Bielefeld. The results demonstrate the feasibility of taking series of 'snapshots' of the electron movement in the atomic shell.

Information: Dr. Markus Drescher, Fakultät für Physik der Universität Bielefeld, Telefon +49.521.106 5470, E-Mail: drescher@physik.uni-bielefeld.de.

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