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Dr. Peter Wochner –
Ultrashort-Time X-Ray Diffraction and Real-Time Relaxation Phenomena
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Ultrafast phenomena: 100 fs are about the time it takes for a light-pulse to pass through a human hair. |
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Many important dynamic processes in condensed matter occur on extremely short
time scales (less than 100 fs). As elementary processes, they often determine
the macroscopic properties of a material. In recent years, new insights into
ultrafast dynamic processes (such as molecular reactions in chemistry) could
be obtained by probing the electronic system using femtosecond laser
spectroscopy (Zewail 1999).
To directly unravel the corresponding
atomic dynamics, however, one needs structural information on atomic
length scales (less than 1 nm) which can be obtained by X-ray diffraction
on ultrashort time scales.
Ultrashort-time X-ray diffraction has only recently become feasible due to
the development of novel X-ray sources and detectors and related experimental
techniques. With the new SASE-XFELs
becoming available, giant coherent X-ray laser sources that are currently being
designed in several places worldwide, a goal seems now to get in reach which
has so far been regarded an unreachable vision in condensed matter research:
the real-time observation of atomic dynamics in matter. One of these intense
new X-ray laser sources is expected to be built as part of the
TESLA-XFEL
project at DESY in Hamburg. Even today, however, some classes of fast structural
changes can already be investigated using small-scale laboratory equipment.
There are two basic concepts for probing
atomic dynamics using X-ray diffraction: pump probe and stroboscopic recording.
Main aspects
With the aid of ultrashort-time X-ray diffraction revolutionary new insights can be obtained in the following fields:
- physical processes in condensed matter,
- chemical reactions, aemical reactions, and
- biological structures and processes.
Some of our future research objectives in the field of condensed matter physics are:
- dynamics of condensed matter in thermal equilibrium
- relaxation of non-equilibrium states
- manipulation of matter on an atomic scale
Current topics
- Structural relaxation of matter after excitation with electromagnetic waves
Job offers
- Please contact Peter Wochner
Contact
Links
