A technique combining SR XRF, XRF mapping, μ-XRF, and μ-XAFS for search for microparticles in different matrices and determination of particle size, as well as analysis of their composition and structure, has been developed at Budker Institute of Nuclear Physics. The technique is based on comprehensive examination of sample with gradually increasing the spatial resolution and constricting the study area for locating the desired microparticle. The beam size for preliminary studies ranges from 1 mm to 100 um in height and 10 mm in width. The next stage is examination using X-ray optics (polycapillary lenses) with single-lens and confocal schemes. The apparatus function of each lens is measured, which enables controlled variation of the focal spot size from 10 um to 70 um.
This multifacet technique was tested on search for and study of micro-inclusions of light platinum group metals (Ru and Pd) in Bushveld (South Africa) Intrusive Complex samples. An area with high concentration of Pd has been found. The particle sizes (~ 50 um) have been identified. A localized particle was studied using the μ-XAFS method. Forms of Pd stabilization in the particle have been established; their structural parameters (interatomic distances and coordination numbers) have been determined.
The work was carried out in the framework of the state assignment for IGM SB RAS and RFBR projects no. 19-05-50046, 18-03-01251. The work was done at the shared research center SSTRC on the basis of the VEPP-4-VEPP-2000 complex at BINP SB RAS, using equipment supported by project RFMEFI62119X0022.