XPS depth profiling of powdered materials

XPS depth profiling of Al/Si ratios in three kinds of zeolite powders was c onducted by both destructive and non-destructive methods. Destructive profi ling with Ar+ sputtering gave Al/Si profiles consistent with those found by non-destructive methods, although the results pointed out possible errors due to preferential sputtering that in fact caused a serious distortion of the Na/Si profile. Analysis of the inelastic peak shape gave qualitative bu t undoubted information on the in-depth profile. Analysis using synchrotron radiation as an energy-tunable excitation source below 1000 eV revealed th e topmost surface composition but could not detect the compositional change in deeper regions. It was concluded that to minimize analytical errors, a combination of the above methods is needed for materials of such complexity . (C) 1999 Elsevier Science B.V. All rights reserved.