Experimental comparison of synchrotron radiation with other modes of excitation of X rays for trace element analysis

Monochromated synchrotron radiation (SXRF), 17.5 keV photons from an X-ray tube (XRF) with Mo anode and 3 MeV protons (PIXE) were used to excite X-ray spectra from thin samples of standard reference materials. Relative detection limits derived from these X-ray spectra were calculated to compare the different excitation modes. XRF shows the highest detection limits, while protons and synchrotron radiation monochromated to 16.5 keV are comparable. Much lower detection limits (down to 0.1 ppm) are experimentally shown with synchrotron radiation monochromated to 9.1 keV. Results are in agreement with theoretical predictions. The advantage of the polarization of the synchrotron radiation has been discussed theoretically and shown experimentally.