Site selectivity is produced by the variable Cu(1) and Cu(2) site
contributions for different Bragg reflections.
Table i lists the calculated values of the
crystallographic weights for each site, 
and 
, for the
eight different (00L) Bragg reflections that were measured. The weights
were calculated using the atomic coordinates reported by Cava, et
al. [29]. Note that there is considerable variation in the
crystallographic weights for these eight (00L) Bragg reflections. All of
these reflections were easily accessible with the 2-circle spectrometer and
the (001) film orientation. Also note that the calculated contributions of
the two sites do not depend on the lattice constant, but only on the
relative positions of the sites within the unit cell.
The Cu weights for the different Bragg reflections listed in Table i have two primary features. First, both sites contribute to all the Bragg reflections. Since a single Bragg reflection cannot be used to determine the local structure of a single Cu site, the contributions to several Bragg reflections are needed to resolve the individual sites. Second, the sign of the Cu(2) weight relative to the Cu(1) weight changes for different Bragg reflections. These sign changes increase the site separation sensitivity, and make it easy to assign near-edge features to a particular site. The assignment of the near-edge features based on these sign changes is discussed in Section 8.1.