Spatial XRF distribution characteristics associated with polarized EDXRF spectrometry

An experiment was designed and carried out to measure the XRF yield distribution over the area irradiated by the target's x-rays in a polarized EDXRF spectrometer. A small solder disc, which was made of mainly lead and tin and with a diameter of about 3 mm, was scanned manually with equal displacements over the area. XRF spectra excited by radiation from three typical targets, namely, highly oriented pyrolytic graphite (HOPIG), Mo and Al2O3, were collected. Intensities of Sn Ka and La and Pb La and Ma lines were obtained and used to describe the XRF yield distributions from different targets. The results showed that the total areas contributing to the XRF signal were over 2 cm 2 for the above three targets. Also, Pb Ma and Sn K alpha maps irradiated by HOPG and Al2O3, respectively, showed very high intensities in the central parts, while they were very low in the periphery. The sum of intensities from four spots in central area (corresponding to about 7 x 7 mm(2)) represents about 50% of overall integrated intensities of the 33 measured spots. Also, the sharpest areas of Pb Ma and Sn Ka were slightly shifted. Pb La maps obtained using the Mo target showed much larger distribution areas, with center being the most intense and becoming weaker gradually toward the outer parts. The relatively small irradiation areas of the polarized targets may require better sample homogeneity, and care should be taken when small pieces of samples are to be analyzed. Copyright (C) 2007 John Wiley & Sons, Ltd.