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Radioactivation methods in general are essential for trace analysis because of their accuracy; among these methods, charged particle activation analysis (CPAA) is especially suitable for the determination of light elements such as boron, carbon, nitrogen, and oxygen at trace levels in materials. CPAA can also be used advantageously for other heavier elements if needed, and sometimes be a complement to neutron activation analysis, or even competes with it. The CPAA is the best reference method because of its high sensitivity and selectivity. It permits the determination of the total concentration, regardless of chemical state. The surface contamination can be eliminated by etching after irradiation and absolute concentrations can be obtained by direct comparison with known compounds. There are no matrix effects and no need for reference samples. This article describes and discusses, in more detail, the principle and some applications of CPAA. Examples are given of typical applications of CPAA technique such as the study the oxygen profiling in Czochralski‐silicon (Cz‐Si) substrates submitted to a rapid thermal annealing, and the study of the oxygen behavior in thermally treated Cz‐Si substrates by combining CPAA with ion channeling.
Radioactivation methods in general are essential for trace analysis because of their accuracy; among these methods, charged particle activation analysis (CPAA) is especially suitable for the determination of light elements such as boron, carbon, nitrogen, and oxygen at trace levels in materials. CPAA can also be used advantageously for other heavier elements if needed, and sometimes be a complement to neutron activation analysis, or even competes with it. The CPAA is the best reference method because of its high sensitivity and selectivity. It permits the determination of the total concentration, regardless of chemical state. The surface contamination can be eliminated by etching after irradiation and absolute concentrations can be obtained by direct comparison with known compounds. There are no matrix effects and no need for reference samples. This article describes and discusses, in more detail, the principle and some applications of CPAA. Examples are given of typical applications of CPAA technique such as the study the oxygen profiling in Czochralski‐silicon (Cz‐Si) substrates submitted to a rapid thermal annealing, and the study of the oxygen behavior in thermally treated Cz‐Si substrates by combining CPAA with ion channeling.
Radioactivation methods in general are essential for trace analysis because of their accuracy; among these methods, charged particle activation analysis (CPAA) is especially suitable for the determination of light elements such as boron, carbon, nitrogen, and oxygen at trace levels in materials. CPAA can also be used advantageously for other heavier elements, if needed, and sometimes be a complement to neutron activation analysis, or even competes with it. The CPAA is the best reference method because of its high sensitivity and selectivity. It permits the determination of the total concentration, regardless of the chemical state. The surface contamination can be eliminated by etching after irradiation, and absolute concentrations can be obtained by direct comparison with known compounds. There are no matrix effects and no need for reference samples. In this article, we have described and discussed, in more detail, the principle and some applications of CPAA. Examples are given of typical applications of CPAA technique such as the study of the oxygen profiling in Czochralski‐silicon (Cz‐Si) substrates submitted to a rapid thermal annealing (RTA) and the study of the oxygen behavior in thermally treated Cz‐Si by combining CPAA with ion channeling. Helium behavior in irradiated UO 2 is an important role in the mechanical stability of nuclear fuels during and after its use in nuclear power plants. Helium migration mechanisms in bulk uranium dioxide (UO 2 ) have already been the subject of theoretical studies, but there is a lack of experimental data relating to the most stable location in the crystal. The question of the helium behavior in silicon carbide 6H–SiC single crystals has been studied at the atomic scale by numerical simulations, but no experiment has been carried out to assess the results hitherto. The measurements have shown that a portion of the He is located in the interstitial tetrahedral sites as predicted by the numerical simulations.
Activation analysis in general and mainly reactor neutron activation analysis (NAA) has been used extensively for measuring trace elements in high purity materials, particularly semiconductor materials. The advantages of NAA in determination of trace elements differ from one semiconductor material to another. For all of them the inherent properties of activation analysis especially those of non contamination with the reagents, low blanks and high sensitivity are the reasons for the choice of NAA as the main analytical procedure. These inherent properties are essential for analysis of high‐purity materials where concentrations of ppb's and sub ppb's have to be measured. NAA is specially suitable for the determination of trace elements in silicon due to the very short lived very low activity induced by neutron reaction in silicon. This enables easy instrumental (i.e. without chemical separations) determination of trace elements in silicon. In the HFR reactor at Peten, Netherlands, a special facility was constructed for irradiation of silicon samples of Philips, in which silicon wafers of up to 15 cm diameter can be irradiated with 4 × 1013n. cm−2. sec−1 and the irradiation is done for 72–96 hours. using large Ge(Li) detectors (100 to 150cc) and long counting time (8–16 hours) they measured 22 elements in concentrations below ppb and 10 others between ppb and 300 ppm. Trace elements in germanium have been determined both instrumentally after very long decay time (100 days) or after short decay time removing the activities from the matrix by chemical separation. Trace elements in GaAs are determined only after chemical separtion. Several other semiconductor material such as Sc, Te, GaP and CuInS2 were also determined by NAA. Some trace elements cannot be determined by neutron activation. Carbon, nitrogen and oxygen are determined by activation with protons, alphas or 3He particles. Boron and hydrogen are determined by prompt emission induced by charged particle activation, which gives not only the total concentration but also the depth profile. Carbon, nitrogen, oxygen and phosphorus were also determined by prompt proton activation analysis. The environmental samples studied by activation analysis can be divided into three categories: atmospheric aerosols, water samples and solid wastes. NAA of atmospheric aerosols have been used for their posible toxicological hazards, their source identification and for studies of atmospheric transport processes.
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