idw – Informationsdienst Wissenschaft
Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
idw - Informationsdienst
Wissenschaft
Team of physicists with members from Jena University publishing details on phase transformation in "Science" magazin
(Jena) How and why does a solid body melt? What is liquid? These simple questions are not as easily answered as one would expect and still the objects of today's research. An international team of scientists succeeded now in observing the real time-movements of atoms during melting, thus gaining new insights into the processes leading to the phase transformation from solid into liquid matter. Exemplarily, the scientists studied the laser-induced, high speed melting of a semi-conductor (Indium-Antimonide) by using a unique new x-ray source, the Sub-Picosecond Pulse Source (SPPS), at the linear accelerator at SLAC in Stanford, USA.
Their detailed research findings, with important contributions from experimental physicist Prof. Dr. Klaus Sokolowski-Tinten (42) of the Jena University, will be published today (15.04.05) in the internationally renowned magazine "Science" ["Atomic-Scale Visualization of Inertial Dynamics", Science, Vol. 308, Heft 5720].
"The process of the laser-induced phase-transformation from solid to liquid is defined by the speed the atoms had just before laser excitation", summarizes Prof. Sokolowski-Tinten the central research findings. The laser pulse instantly breaks the chemical bonds between the atoms thus removing the "glue" that keeps the solid together. The scientists were able to observe that the materials starts to disorder as a consequence of this excitation, but because of inertia, the atoms initially just keep their initial motion. This movement is unsystematic and conditioned by the room-temperature thermal motion of the atoms. "One atom doesn't know what the other does, and the material is in a strange intermediate state: on the one hand the atoms are still systematically arranged like in a crystalline solid, but on the other hand they already behave like atoms in a liquid." explains the physicist from the Friedrich Schiller University of Jena.
Essential for the success of the experiment were the short x-ray pulses of the SPPS, the first x-ray source enabling pulses of less than 100 femtoseconds (1 fs = 10 high minus 15 s). "That is at least three times faster than our x-ray possibilities so far. Because laser induced melting turned out to be so fast the experiment would not have worked with longer pulses", emphazises Prof. Sokolowski-Tinten, whose field of expertise at the Institute for Optics and Quantum Electronics of the Jena University is ultrafast x-ray physics. "Not only did we learn something new about fast melting; we were also able to demonstrate that it is possible to do ultrafast experiments with such accelerator-based x-ray sources", says Sokolowski-Tinten. That is why the experiment at the SPPS is of such exemplary significance for the large free electron electron laser projects (LCLS at Stanford and EURO-XFEL with DESY in Hamburg). Prof. Sokolowski-Tinten thinks that "SPPS gives us a first impression of the things that will be possible in the future." With those "4th generation light sources" researchers will be able to follow chemical reactions in real time, decode the atomic structure of (bio)molecules, and take three-dimensional pictures of the nano-world.
Contact:
Prof. Dr. Klaus Sokolowski-Tinten
Institut für Optik und Quantenelektronik der Universität Jena
Max-Wien-Platz 1, 07743 Jena
Tel.: 0049 / (0)3641 / 947250
E-Mail: sokolowski@ioq.uni-jena.de
Prof. Dr. Klaus Sokolowski-Tinten
Photo: Scheere/FSU
None
Merkmale dieser Pressemitteilung:
Mathematik, Physik / Astronomie
überregional
Forschungsergebnisse
Englisch
Sie können Suchbegriffe mit und, oder und / oder nicht verknüpfen, z. B. Philo nicht logie.
Verknüpfungen können Sie mit Klammern voneinander trennen, z. B. (Philo nicht logie) oder (Psycho und logie).
Zusammenhängende Worte werden als Wortgruppe gesucht, wenn Sie sie in Anführungsstriche setzen, z. B. „Bundesrepublik Deutschland“.
Die Erweiterte Suche können Sie auch nutzen, ohne Suchbegriffe einzugeben. Sie orientiert sich dann an den Kriterien, die Sie ausgewählt haben (z. B. nach dem Land oder dem Sachgebiet).
Haben Sie in einer Kategorie kein Kriterium ausgewählt, wird die gesamte Kategorie durchsucht (z.B. alle Sachgebiete oder alle Länder).
