The direct spline method is analogous to standard XAFS analysis. It splines
the measured DAFS intensity, subtracts the spline from the data, and
normalizes the resulting fine structure signal to the spline. In its
simplest form, it produces an effective function that contains a
mixture of the , and components. If the data
is divided by the measured absorption correction before it is splined, the
function will still contain a mixture of and
components. The measured intensity can be related to the theoretical
intensity (Eqn. 10) by , where *C*(*E*)
accounts for the energy dependent instrument correction factors. The
measured intensity is fit with a smooth spline , and the fine structure is separated from the measured
intensity by subtracting the spline from the data. The fine structure is
normalized by dividing by to yield the
effective function,

Note that the site specific and signals can be
determined from the effective function if the real and imaginary
parts of the smoothly varying background, and , and the crystallographic weights, , can be determined.