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Figure 14
(a) A detector image of the Al Kα line as the sample is moved to various positions along the XFEL beam to test the imaging capabilities of the spectrometer. The vertical energy scale is not relevant here since the beam was intentionally defocused vertically to reduce intensity, and the energy resolution is therefore limited. (b) Curves achieved by projecting the image on the horizontal scale. (c) An enlarged projected image with curve fitting. The FWHM = 0.35 mm refers to the appearance on the detector. With a tenfold magnification this corresponds to 35 µm along the beam. The non-symmetric appearance is due to the slight off-center position of the source. |