Elemental Mapping of Biological Tissue by X-Ray Absorption Difference Imaging in the STXM

A number of microscopic techniques are used to produce images containing information on the distribution of the elements in biological tissue. Principally, these are visible and U.V. microscopy fluorescence light microscopy, EDS electron microscopy, WDS electron microscopy, EELS electron microscopy, and SIMS. Of the above techniques, those most widely used for elemental mapping are visible/U.V. light microscopy [1] and EDS electron microscopy [2]. With the advent of bright x-ray sources and improving x-ray optics, it is now possible to image a range of elements (in wet and dry systems) using soft x-rays in the scanning x-ray microscope (STXM). X-ray absorption difference imaging (XADI) utilizes natural changes in the absorption of x-rays for small increments in x-ray energy to produce an elemental map of a specimen.