Hannover 2010 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

MO: Fachverband Molekülphysik

MO 7: Poster: Femtosecond Spectroscopy

MO 7.13: Poster

Dienstag, 9. März 2010, 16:00–18:30, Lichthof

Challenges in single-particle diffractive imaging with intense Xray pulses — •Martin Winter, Christian Gnodtke, Ulf Saalmann, and Jan-Michael Rost — Max Planck Institut fuer Physik komplexer Systeme, 01187 Dresden, Germany

The construction of short-wavelength free-electron lasers (FEL) allows for the investigation of intense laser-matter interaction at the so far unexplored Xray regime. The FEL at LCLS/Stanford is the first one reaching short intense pulses with photon energy in the keV range. One of the main objectives of these machines is the imaging of single molecules by measuring diffraction images from exposure by the beam.

We will discuss two complementary issues which have to be overcome to obtain diffraction images whereof the molecular structure can be successfully reconstructed. 1) The damage, in particular the ionization of the sample, induces an explosion on the time scale of the pulse. We discuss the impact of a tamper [1,2] which slows down the expansion and thus may improve the diffraction image. 2) Due to the small elastic-scattering cross sections diffraction images obtained will be very faint, which makes the determination of the orientation of the molecule challenging. We have implemented a method based on the generative topographic mapping [3] and will discuss its application to two-dimensional diffraction images.

References: [1] C. Gnodtke, U. Saalmann and J. M. Rost, Phys. Rev. A 79, 041201 (2009) [2] S. P. Hau-Riege et al., Phys. Rev. Lett. 98, 198302 (2007) [3] R. Fung, V. Shneerson, D. K. Saldin and A. Ourmazd, NPHYS 1129 (2008)