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Powder DAFS

There have already been demonstration experiments showing that the wavevector and site selectivities of DAFS can be obtained using synchrotron powder diffraction [9]. There has also been considerable powder diffraction community interest in the valence and orbital sensitivity provided by the DANES features [35]. It has been difficult, however, to obtain adequate diffracted beam intensities using second-generation synchrotron radiation sources equipped with conventional detectors. In addition, the absorption corrections and background fluorescence problems are much more severe for powder samples than they are for the thin epitaxial film samples described in this chapter. The availability of third-generation synchrotron radiation sources and of better detectors will enhance the capabilities of powder DAFS. Detectors which provide energy discrimination (to remove the fluorescence) and which provide parallel data acquisition over the full Debye-Sherrer ring or at many simultaneous 2tex2html_wrap_inline2130 values (to provide more signal) will allow greatly improved measurements at second- or third-generation sources.