XRF with SR micro beams in the study of geological samples.
- Mr. Fedor DARIN
- Mr. Fedor DARIN (Budker Institute of Nuclear Physics SB RAS)
Micro beams of synchrotron radiation at the experimental station of elemental analysis in the storage ring VEPP-3 obtained using polycapillary focusing optics. The minimum sizes of the exciting radiation spot with an energy of 8 – 25 keV on the sample surface is 10x15 square microns. This allows us to make detailed studies of the elemental composition of various geological samples: mono crystals, inclusions, annual layers in the bottom sediments and other. A set of analyzed elements depends on the excitation energy. For the energy of 25 keV it is possible to analyze about 30 rock-forming and trace elements: K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag using K-series, and Ta, W, Au, Pb, Th, U using L-series. The detection limits for light elements (K, Ca) are estimated to be 500-300 ppm, for Pd, Ag in optimal conditions, the detection limit is about 50-100 ppb. Local microanalysis or two-dimensional scanning is possible using one focusing lens. One can make a three-dimensional study of micro inclusions by using confocal scheme of experimental station (two lenses scheme). Also instrumental functions of pollycapilary lenses and confocal x-ray microscope were calculated to vary spot size on the sample (in range from 10 to 100 microns) and confocal volume size.