Premium
Improvement in detection limits by using helium ions for particle‐induced x‐ray emission
Author(s) -
Beck Lucile
Publication year - 2005
Publication title -
x‐ray spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.447
H-Index - 45
eISSN - 1097-4539
pISSN - 0049-8246
DOI - 10.1002/xrs.854
Subject(s) - bremsstrahlung , helium , ion , ionization , atomic physics , stopping power , electron , materials science , physics , analytical chemistry (journal) , chemistry , nuclear physics , quantum mechanics , chromatography
PIXE analysis is usually carried out by using protons as the incident projectiles. Protons generally present the advantages of large penetration depth and high ionization power. However, the use of heavier ions can be useful in a specific context. Deuterons or helium‐4 ions produce negligible nuclear bremsstrahlung for matrix elements whose Z / A is close to 0.5 and the secondary electron bremsstrahlung is shifted to lower x‐ray energies. Thanks to the reduction of these backgrounds, better limits of detection are expected. In this study, helium‐induced x‐ray emission (HIXE) analysis was applied to various thick specimens. We observed that the detection of light trace elements in medium‐ Z matrices can be improved by selecting an appropriate energy for the helium ion beam. For calcite, brass or casting iron, the signal‐to‐background ratios for Mg, Si, P, S, etc. are enhanced by using helium ions instead of protons. Moreover, as the intensity of the major element peaks (Ca, Cu or Fe) is low, the use of x‐ray absorbers for limiting the counting rate is less necessary. As a result, the detection limits of the low elements in these matrices are reduced by a factor of two. Copyright © 2005 John Wiley & Sons, Ltd.