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- ItemUltrafast inter-ionic charge transfer of transition-metal complexes mapped by femtosecond x-ray powder diffraction(Les Ulis : EDP Sciences, 2013) Zamponi, F.; Freyer, B.; Juvé, V.; Stingl, J.; Woerner, M.; Chergui, M.; Elsaesser, T.Transient electron density maps are derived from x-ray diffraction patterns of photoexcited [Fe(bpy)3]2+(PF6 -)2 powder. Upon photoexcitation, the 5T 2 quintet state reveals a charge transfer from the PF 6- ions and from the Fe atoms to neighboring bpy units. The charge transfer from the Fe points to a partial and weak charge-transfer character of this state.
- ItemFemtosecond x-ray diffraction using the rotating crystal method(Les Ulis : EDP Sciences, 2013) Freyer, B.; Stingl, J.; Zamponi, F.; Woerner, M.; Elsaesser, T.We demonstrate the rotating-crystal method in femtosecond x-ray diffraction. Structural dynamics of a photoexcited bismuth crystal is mapped in a pump-probe scheme by measuring intensity changes of many Bragg reflections simultaneously.
- ItemUltrafast charge relocation in an ionic crystal probed by femtosecond x-ray powder diffraction(Les Ulis : EDP Sciences, 2013) Woerner, M.; Zamponi, F.; Rothhardt, P.; Stingl, J.; Elsaesser, T.Transient electron density maps of potassium dihydrogen phosphate(KH 2PO4, KDP) are derived from femtosecond x-ray powder diffraction patterns. Upon photoexcitation, the low-frequency TO soft mode is elongated impulsively and modulates the electronic charge distribution on the length scale of interatomic distances, much larger than the vibrational amplitude of the nuclear motion. The results demonstrate a charge transfer from the volumes around the P-atoms to those containing the O - H·· ·O units and a quadrupolar distortion of the K+ charge distribution. This behavior reflects the interplay of nuclear motions and electric polarizations in the ionic crystal lattice.