Hannover 2010 – wissenschaftliches Programm
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SYDI: Symposium Diffractive Imaging
SYDI 2: Diffractive Imaging of complex molecules in the gas-phase
SYDI 2.2: Hauptvortrag
Freitag, 12. März 2010, 14:30–15:00, E 415
Time-resolved diffraction from selectively aligned molecules — •Ernst Fill1, Martin Centurion2, Peter Reckenthäler1, Werner Fuß1, and Ferenc Krausz1 — 1Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching — 2Dept. of Physics and Astronomy, University of Nebraska, Lincoln, NE 68588-0111, USA
The random directions of molecules in a gas result in diffraction patterns in the form of isotropic rings. Their evaluation yields information only on the radial distribution function i.e. on interatomic distances. However, by dissociation with linearly polarized light molecules are partially aligned and the pattern becomes anisotropic. In our experiments the iodide C2F4I2 is dissociated by fs UV pulses and molecular difference intensities and difference radial distribution curves are measured for directions parallel and perpendicular to the direction of polarization. The curves clearly demonstrate transient anisotropy of the diffraction pattern. The anisotropy decays by molecular rotation with a time constant depending on the rotational temperature. In our experiments we measure decay within 2.6 ps. This experiment is a first step towards the determination of the structure of complicated molecules by alignment methods.