X-ray laser–induced electron dynamics observed by femtosecond diffraction from nanocrystals of Buckminsterfullerene

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Science Advances  09 Sep 2016:
Vol. 2, no. 9, e1601186
DOI: 10.1126/sciadv.1601186


  • Fig. 1 Schematic of the experimental geometry used to collect the diffraction data.

    XFEL pulses (10 keV, 32 fs) acted as a simultaneous pump and probe when passing through the C60 nanocrystal powder sample, which was supported on a thin kapton film. A removable silicon attenuator upstream of the sample controlled the incident intensity and could be inserted for 10% or removed for 100% incident beam power. An aluminum attenuator (not shown) was placed directly in front of the CSPAD detector downstream of the sample to prevent the pixels from saturating. The direct beam passed through a small aperture in the CSPAD detector modules.

  • Fig. 2 C60 diffraction data.

    (A) Summed diffraction data from 2500 single shots recorded at 100% power. The semitransparent red circle indicates the location of one of the reflections only observed in the 100% XFEL data. (B) Enlarged region from (A) showing Bragg peaks at 10% power, consistent with the room temperature FCC structure. (C) The same region as in (B) collected at 100% power. To enhance contrast, Embedded Image has been displayed. (D) Azimuthally averaged experimental XFEL data for 10 and 100% incident power and synchrotron data collected from the same C60 sample. Vertical lines indicate positions of FCC Bragg reflections. Between 20° and 28°, significant differences are observed between the synchrotron and the 10 and 100% XFEL data.

  • Fig. 3 Comparing experimental and simulated data.

    (A) Schematic representation of the alignment of polarized C60 molecules. (B) Comparison of the 100% XFEL data and the model prediction based on the newly predicted, lower symmetry, structure. Directly below the plot are tick marks indicating the predicted model peak positions; because of the finite experimental resolution, not all of these peaks are resolved in the data. The black line shows the difference between the model and experimental data.

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