Grazing-exit particle-induced X-ray emission analysis with extremely low background

The grazing-exit technique is applied to particle-induced X-ray emission (P IXE) analysis of thin-films and aerosols deposited on nat silicon wafers. P IXE is known as a trace-analytical method; however, Bremsstrahlung backgrou nd is still important in the low-energy region. A 2.5 MeV proton beam bomba rded the sample at an incident angle of 90 degrees, and the emitted X-rays were detected at grazing exit angles by using an energy-dispersive detector . When the characteristic X-rays were measured at grazing exit angles, this background almost disappeared. The characteristic X-rays of Ca K alpha and Zn K alpha emitted from atmospheric particles could hardly be observed by PIXE in the normal arrangement; however, they were clearly observed with lo w background under grazing-exit conditions. The detection limit for Ca was improved by a factor of 7, It is also demonstrated that analysis of the top most layer and depth analysis for double-layered samples are both possible by adjusting the exit angle. Consequently, grazing-exit PIXE is a promising method for surface-, micro-, and trace analysis.