Separation of weak EXAFS signal from atomic background in Br and Rb samples

In EXAFS analysis of Rb-doped silicate glasses and of cetyltrimethylammoniu m bromide (CTAB) adsorbed on carbon black, the spline approximation of the atomic background is inadequate. Instead, a residuum obtained from absorpti on spectra of Rb and Br ions in aqueous solution after removal of the struc tural signal is used. Another iteration cycle whereby the residuum from one sample in the atom-ion pair is used in analysis of the other one, gives sa tisfactory convergence. In this way, definite FEFF models of Rb glass and C TAB are constructed, and a better approximation for atomic absorption obtai ned as residual.