Confocal micro-X-ray fluorescence and total reflection X-ray fluorescence analyses of Ryugu sample in a laboratory environment.

This study analyzed Ryugu samples utilizing confocal micro-X-ray fluorescence (CM-XRF) and total reflection X-ray fluorescence (TXRF), in which information of elemental mapping as well as the content of trace elements could be obtained separately, and respectively. In CM-XRF, polycapillary lenses are placed in front of the X-ray tube and detector, and elemental information in the overlapping region of both focus points was obtained. Three-dimensional elemental distributions could be obtained by scanning a sample; the Ryugu sample was placed on an Al plate with one center, and the images of Fe, Ni, Cr, and Ca were obtained. The outlines of these elements were almost equivalent; however, as the energy of Ca Kα was low, its intensity in the elemental mapping was weak. Non-destructive TXRF measurements were performed to measure the trace elements in the Ryugu sample. We then performed quantitative analysis and determined the concentrations of trace elements such as Ga, Ge, and Se. The concentrations of these elements are higher than those in the CI chondrites. Therefore, we verified that the 3D elemental distributions and quantitative measurements in the Ryugu sample were performed without destruction.