Ursula Keller wins “Swiss Nobel” Marcel Benoist Prize
Farewell: the NCCR MUST ended 
MUST2022 Conference
New scientific highlights
FELs of Europe prize for Jeremy Rouxel
Ruth Signorell wins Doron prize
New FAST-Fellow Uwe Thumm at ETH
International Day of Women and Girls in Science
New scientific highlight
EU XFEL Young Scientist Award for Camila Bacellar,
Prizes for Giulia Mancini and Rebeca Gomez Castillo
Nobel Prize in Chemistry awarded to RESOLV Member Benjamin List
Hans Jakob Wörner invited to give the „New Horizons Solvay Lectures” 
Unusual keynote talk at an international scientific conference
NCCR MUST at Scientifica 2021X-ray multiphoton ionization and the phase problem in coherent diffractive imaging
| Date | Di, 24.09.2013 | |
| Time | 16:45 | |
| Speaker | Prof. Dr. Robin Santra, Center for Free-Electron Laser Science, Hamburg, Germany | |
| Location | ETH Zurich, Hönggerberg Campus, HCI J 3 | |
| Program | The coherent x-ray scattering pattern of a molecule is connected to the modulus squared of the Fourier transform of the electron density of the molecule. The phase of this Fourier transform is not measured. As a consequence, a reconstruction of the electron density—and thus of the molecular structure—is not immediately possible. In x-ray crystallography at storage-ring-based synchrotron radiation sources, the multi-wavelength anomalous diffraction (MAD) method is used to determine phase information by employing anomalous scattering from heavy atoms. X-ray free-electron lasers (FELs) provide the extremely high x-ray intensity required for revealing the structure of single molecules or nanocrystals, but the phase problem remains largely unsolved. A particular challenge is that, at high x-ray intensity, samples experience severe electronic radiation damage, especially to heavy atoms, which hinders direct implementation of MAD with x-ray FELs. In the first part of the talk, I will discuss how MAD phasing can be extended to high x-ray intensity [1]. The proposed technique relies on the existence of a Karle-Hendrickson-type equation in the high-intensity regime and requires the ability to computationally predict the x-ray-induced ionization dynamics of heavy atoms. In the second part of the talk, this ability will be put to the test. I will review x-ray FEL experiments that have been carried out on atomic xenon and will compare the observations to extensive first-principles calculations [2,3]. At sufficiently high photon energies, there is good agreement between experiment and theory. However, close to inner-shell edges, which play a key role for MAD phasing, specific discrepancies are found. A strategy will be discussed that is expected to allow us to eliminate these discrepancies. [1] S.-K. Son, H. N. Chapman, and R. Santra, Phys. Rev. Lett. 107, 218102 (2011). [2] B. Rudek et al., Nature Photonics 6, 858 (2012). [3] H. Fukuzawa et al., Phys. Rev. Lett. 110, 173005 (2013). Host: Hans Jakob Wörner, Laboratorium für Physikalische Chemie, LPC |
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