ABSTRACT
XRF (X-ray fluorescence) is a powerful technique for elemental analysis with a high sensitivity. The resolution is presently limited by the size of the primary excitation X-ray beam. A test-bed for confocal-type XRF has been developed to estimate the ultimate lateral resolution which could be reached in chemical mapping using this technique. A polycapillary lens is used to tightly focus the primary X-ray beam of a low power rhodium X-ray source, while the fluorescence signal is collected by a SDD detector through a cylindrical monocapillary. This system was used to characterize the geometry of the fluorescent zone. Capillary radii ranging from 50 µm down to 5 µm were used to investigate the fluorescence signal maximum level This study allows to estimate the ultimate resolution which could be reached in-lab or on a synchrotron beamline. A new tool combining local XRF and scanning probe microscopy is finally proposed.
ABSTRACT
Phoenician ivory objects (8(th) century B.C., Syria) from the collections of the Badisches Landesmuseum, Karlsruhe, Germany, have been studied with full field X-ray fluorescence microimaging, using synchrotron radiation (SR-FF-microXRF). The innovative Color X-ray Camera (CXC), a full-field detection device (SLcam), was used at the X-ray fluorescence beamline of the ANKA synchrotron facility (ANKA-FLUO, KIT, Karlsruhe, Germany) to noninvasively study trace metal distributions at the surface of the archeological ivory objects. The outstanding strength of the imaging technique with the CXC is the capability to record the full XRF spectrum with a spatial resolution of 48 µm on a zone of a size of 11.9 × 12.3 mm(2) (264 × 264 pixels). For each analyzed region, 69696 spectra were simultaneously recorded. The principal elements detected are P, Ca, and Sr, coming from the ivory material itself; Cu, characteristic of pigments; Fe and Pb, representing sediments or pigments; Mn, revealing deposited soil minerals; Ti, indicating restoration processes or correlated with Fe sediment traces; and Au, linked to a former gilding. This provides essential information for the assessment of the original appearance of the ivory carvings. The determined elemental maps specific of possible pigments are superimposed on one another to visualize their respective distributions and reconstruct the original polychromy and gilding. Reliable hypotheses for the reconstruction of the original polychromy of the carved ivories are postulated on this basis.
ABSTRACT
A new versatile tool, combining Shear Force Microscopy and X-Ray Spectroscopy was designed and constructed to obtain simultaneously surface topography and chemical mapping. Using a sharp optical fiber as microscope probe, it is possible to collect locally the visible luminescence of the sample. Results of tests on ZnO and on ZnWO4 thin layers are in perfect agreement with that obtained with other conventional techniques. Twin images obtained by simultaneous acquisition in near field of surface topography and of local visible light emitted by the sample under X-Ray irradiation in synchrotron environment are shown. Replacing the optical fibre by an X-ray capillary, it is possible to collect local X-ray fluorescence of the sample. Preliminary results on Co-Ti sample analysis are presented.
ABSTRACT
A detector that looks promising for advanced imaging modalities--such as X-ray absorption contrast imaging, X-ray fluorescence imaging, and diffraction-enhanced imaging--is the controlled-drift detector (CDD). The CDD is a novel two-dimensional X-ray imager with energy resolving capability of spectroscopic quality. It is built on a fully depleted silicon wafer and features fast readout while being operated at or near room temperature. The use of CDDs in the aforementioned applications allows translating these techniques from synchrotron-based experiments to laboratory-size experiments using polychromatic X-ray generators. We have built a dedicated and versatile detection module based on a 36 mm2 CDD chip featuring pixels of 180 x 180 microm 2, and we evaluated the system performance in different X-ray imaging applications both with synchrotron-based experiments and in the laboratory environment.
