Spatial speciation with soft x-ray analysis
Traditional microanalysis measures the intensity of x-ray lines to determine chemical composition. The energy and shape of these x-ray lines can subtly vary with changes in the chemical environment.
Using a high resolution x-ray detector, such as the soft x-ray detectors fitted to our electron microprobe (EPMA) and scanning electron microscope (FEG-SEM). The soft x-ray detector collects x-rays from an energy region in parallel, with high energy resolution compared to wavelength dispersive spectrometers (WDS) or energy dispersive spectrometers (EDS). The soft x-ray detector fitted to the EPMA can detect x-rays with energies as low as 45 eV to 210 eV, while the spectrometer on the SEM can detect x-rays up to 3keV.
The figure to the right demonstrates the differentiation of Cr6+ from Cr3+. A distinct shift in the position of the Cr L𝛼 x-ray line can be seen between the hexavalent lead chromate and the other chromium(III) materials.
High resolution X-ray spectra showing peak movement of the Cr L𝛼 x-ray line. A difference can be seen in the peak position of the Cr6+ lead chromate, compared to the other Cr3+ materials.