DEPTH-SELECTIVE CHEMICAL-STATE ANALYSIS OF FINE PARTICLES USING X-RAY-ABSORPTION

We have developed a new chemical state analysis method for fine particle powders-depth-selective X-ray absorption fine structure spectrometry. Recording both the sample current and the X-ray fluorescence intensity concurrently with the change of incident X-ray energy made it possible to obtain surface (10-100 Angstrom) and bulk chemical information on powder samples. Examples are presented for prefractionated coal fly ashes in which we found chemical state differences owing to the probe depth and the coal origin, The coal ny ash contains S2- in the bulk and S6+ in the 10-100 a surface. The ratio of S2-/S6+ varies with changes in coal origin, depth from the particle surface, and particle size.