The ID21 at ESRF is a beamline dedicated to X-ray and FTIR micro-spectroscopy. Localization and speciation of trace elements is primarily done using micro-X-ray fluorescence (µXRF) and micro X-ray absorption spectroscopy (µ-XANES) in the tender X-ray domain (2-9.2 keV). Typical scientific questions concern the co-localization and/or speciation of trace elements in heterogeneous matrices at the submicron scale, with applications in the fields of Environmental Sciences, Earth and Planetary Sciences, Life Sciences and Cultural Heritage. ID-21 has sensitivity in the low ppm range and allows localization with a sub-micron beam of various elements.

The SXM offers a very high versatility in terms of focusing optics, detection and sample environment. The X-ray beam spot size can be tuned from macro (200 µm) to sub-micro (~500 nm), which then allows localization of trace elements at subcellular level. A large panel of complementary detectors is available and provides: high sensitivity, high throughput, or high spectral resolution, which enables the collection of µ-XRF and µ-XANES spectra on a large variety of samples. The samples can be studied in various conditions (room temperature, cryo, wet cells). Additionaly, ID21 has a SR-based FTIR end-station that can provide complementary molecular mapping, with a ~5µm lateral resolution.