Stereo soft X-ray microscopy and elemental mapping of haematite and clay suspensions.

The combination of high-resolution chemically sensitive soft X-ray microscopy with stereo imaging and processing techniques presented here forms a novel tool for the investigation of aqueous colloidal systems. Information about the spatial distribution within the sample is provided with small calculation effort processing just a pair of stereo micrographs. Thus, the extension towards investigation of dynamical behaviour is possible on the part of the experiment as well as of the processing. The potential of this technique is demonstrated with applications in aqueous soil and clay samples. Within these samples, haematite particles are identified taking advantage of the elemental contrast at the Fe-L edge around E= 707 eV. In combination with stereo microscopy, information about spatial arrangements are revealed and correlated to electrostatic interactions of the different mixtures, addressing to an actual question of soil scientists. The technique allows in-situ sample manipulation, which is demonstrated by a test specimen where particles were added during imaging.