Micro-crystalline inclusions analysis by PIXE and RBS

A characteristic feature of the nuclear microprobe using a 3 MeV proton beam is the long range of particles (around 70 \mu m in light matrices). The PIXE method, with EDS analysis and using the multilayer approach for treating the X-ray spectrum allows the chemistry of an intra-crystalline inclusion to be measured, provided the inclusion roof and thickness at the impact point of the beam (Z and e, respectively) are known (the depth of the inclusion floor is Z + e). The parameter Z of an inclusion in a mineral can be measured with a precision of around 1 \mu m using a motorized microscope. However, this value may significantly depart from Z if the analyzed inclusion has a complex shape. The parameter e can hardly be measured optically. By using combined RBS and PIXE measurements, it is possible to obtain the geometrical information needed for quantitative elemental analysis. This paper will present measurements on synthetic samples to investigate the advantages of the technique, and also on natural solid and fluid inclusions in quartz. The influence of the geometrical parameters will be discussed with regard to the concentration determination by PIXE. In particular, accuracy of monazite micro-inclusion dating by coupled PIXE-RBS will be presented

Effects of irradiation damage on the back-scattering of electrons: Silicon-implanted silicon

Radiation damage in a (initially crystalline) silicon wafer was generated by microbeam ion implantation with 600 keV Si+ ions (fluence 5 x 10(14) ions/cm(2)). To produce micro-areas with different degrees of damage, 14 implantations at different temperatures (between 23 and 225 degrees C) were done. The structural state of irradiated areas was characterized using Raman spectroscopy and electron back-scatter diffraction. All irradiated areas showed strong structural damage in surficial regions (estimated depth contrast in our sample, this observation again supports the hypothesis that structural radiation damage may strongly affect BSE images of solids