Experimental verification of a new quantification procedure for elemental mapping by analytical X-ray microscopy

A new procedure has been recently suggested for elemental mapping in X-ray microscopy and the first experimental applications of this procedure are the subject of the present paper. It is applied, first, to a test specimen of known composition and the deduced concentrations deviate from the nominal ones by less than 5% when an additional correction procedure is used for taking into account the pseudo monochromaticity of the acquired images. The same approach is next applied to a ternary (Al/Cr/Ni) alloy, 90 μm thick, and to the mapping of CuSO4 and FeSO4 in solution during a dissolution/deposition process. These results demonstrate the advantages of the suggested procedure with respect to conventional differential X-ray microscopy. These advantages are the minimization of the different radiations to be used, the relaxation for the choice of the X-ray photon energies and the possibility to obtain in addition a surface atomic density (at cm−2) map. The results also illustrate the advantage of X-ray shadow microscopy for a rapid analysis of thick (∼0.1 mm) specimens and its sensitivity (close to 10 ppm in at/at) for the detection of medium elements embedded in very light matrices when the initial X-ray images are acquired by the use of a cooled CCD camera. The short exposure time for the data acquisition of the initial images leads to time dependent concentration maps related to specimen areas of several mm2 with a resolution of around a few micrometers (385 × 578 pixels). The combination of all these advantages lead to the mapping of slowly moving species in a liquid, opening a new field of investigation: that of chemistry and electrochemistry of wet solutions.