A new method to extract the X-ray absorption fine structures from the reflectivity spectra : application to the study of (Ti, Nb) O2 amorphous solid solutions
Abstract
The problem encountered for the extraction of structural or chemical
informations from the X-ray reflectivity are as follows: One is that
absorption and dispersion are mixed except for 8 >> I3 (critical
angle reference Bc= 9mrad). But if 8 is very small, the mkgnitude of
the signal is very weak. On the contrary for 8 N 8=, the height of
the edge is large but strongly distorted by the anomalous dispersion
effect. The second problem is that the absolute value of the
reflectivity is unknown because of the roughnesss of the surface of
the sample, together with the beam divergence which gives an overall
slope to the reflectivity i.e. a pure experimental effect. Needing
to study the X-ray absorption Ti K edge of the (Ti,Nb)O amorphous
solid solutions, we have written a program running on I&+ PC-XT or
compatible which takes into account the problems described above to
correct the X-ray reflectivity spectrum in order to obtain the
absorption spectrum.