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 2
values (to provide more signal) will allow
greatly improved measurements at second- or third-generation sources.