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Abstract  

A method of radioactivation analysis has been developed for the determination of chromium. It is based on the substoichiometric extraction of chromium diethyldithio-carbamate into methyl-isobutyl-ketone from acetate buffer solution in the presence of EDTA and potassium cyanide. The method has been applied for the determination of chromium in high-purity calcium carbonate and NBS glasses as standard reference materials.

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Abstract  

Oxygen in silicon was determined by the secondary nuclear reactions of6Li(n, α)T and16O(t, n)18F. Lithium fluoride was deposited in vacuum on fused quartz, covered with the sample and irradiated in a nuclear reactor. The depth profiles of18F in fused quartz and in silicon were observed, and enough depth to eliminate surface oxygen was estimated. On the basis of these results, oxygen was determined by the average cross-section method. Oxygen concentration in CZ silicon with various growing condition was 5–26 ppm and was consistent with those determined by the infrared absorption method. The detection limit of oxygen in silicon is 5 ppm.

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Abstract  

The effectiveness of charged particle (alpha) activation analysis in determining the content of ion-implanted boron on the surface of Si wafers and the doped boron in epitaxially grown Si film and SiO2 film was evaluated. The method was found to be accurate and precise if interference from surface contamination and the matrix were accounted for and an appropriate standardization method was used.

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Abstract  

Instrumental charged particle activation analysis (CPAA) for determining boron in a thin surface layer of silicon was developed. The nuclear reaction and incident energy were selected in order to minimize any interference from surface or bulk impurities. Thin boron film was used as a standard sample and its boron content was determined by neutron induced prompt -ray analysis. As a result, we were able to determine11B and10B at 1015 atoms/cm2 with an accuracy of better than 3% by 4 MeV proton and 7 MeV -bombardment, respectively. Each boron isotope could be determined down to 1013 atoms/cm2. Our CPAA was applied to determine boron in a boron implanted silicon wafer of a SIMS standard sample.

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Abstract  

In order to determine iron on silicon wafer surface at a level of 1014 atoms·m–2 the efficiency of a well-type Ge detector for59Fe -ray emissions was measured and a low temperature silicon direct bonding technique was developed. With silicon direct bonding at a temperature of 350 to 650°C iron remains near the interface of the bound silicon. The iron contamination of the interface escaped from the interface can be ignored with this technique. The value of iron obtained was (2.7 to 5.9)·1014 atoms · m–2 in the surface on silicon wafers.

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Abstract  

The radiochemical separation of nitrogen was studied for the determination of ultra trace carbon in gallium arsenide by deutron activation analysis using the12C/d, n/13N reaction. It is based on steam distillation as ammonia and successive substoichiometric precipitation as ammonium tetraphenylborate. It was found that the decontamination factors of coexistent elements such as72Ga,76As and11Co to13N are enough large to determine carbon as low as 1 ppb in gallium arsenide.

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Abstract  

We have developed charged particle activation analysis to determine light elements at a sub-ppb level. This analytical method is characterized by sample bombardment with charged particles at a few tens of mA and substoichiometric separation for13N,11C and18F within two half-life times and with decontamination factors of more than 108. Nuclear reactor interference is also estimated with this method. This analytical method is confirmed to be useful for characterizing highly purified materials from analytical results for boron, carbon, nitrogen and oxygen in Nb refined by the floating zone melting method.

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Abstract  

Oxygen was determined in three kinds of ZrF4-based fluoride glass [ZrF4–BaF2–GdF3–AlF3 (ZBGA), ZrF4–BaF2–LaF3–YF3–AlF3–LiF–NaF (ZBLYALN) and ZrF4–BaF2–LaF3–YF3–AlF3–LiF (ZBLYAL)] used for fabricating optical fiberby18O(p, n)18F reaction without significant nuclear interference. The main long life96Nb nuclide was produced by the96Zr(p,n) reaction in a non-destructive analysis of ZBGA-fluoride glass and reduced by using a coincidence system with Ge(Li) and NaI(T1) detectors. Substoichiometric separation of18F was also used to determine oxygen in fluoride glass, especially in glass containing yttrium as a component element because the89Zr produced by the89Y(p,n) reaction is a positron emitter, the same as18F. It was confirmed that the oxygen concentration in fluoride glass was 13–2460 ppm related to the loss by scattering.

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Study on the comparator method using substoichiometry

II. Simultaneous multielement determination of rare earth elements

Journal of Radioanalytical and Nuclear Chemistry
Authors:
M. Katoh
,
T. Shigematsu
, and
H. Yonezawa

Abstract  

The comparator method using substoichiometry is developed. In the method, the contents of the elements can be determined simultaneously by the measurement of radioactivities of the comparator elements and of simultaneously separated parts of the elements in question. The method is applied to the simultaneous determination of rare earth elements, such as lanthanum, europium and terbium in NBS botanical standard reference materials. It is confirmed that the method is reliable for simultaneous multielement determination.

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Abstract  

Ultra trace carbon in gallium arsenide has been determined by deuteron activation analysis. It consists of steam distillation of nitrogen as ammonia and successive substoichiometric precipitation as ammonium tetraphenylborate. It is confirmed that nitrogen is precipitated substoichiometrically as ammonium tetraphenylborate in spite of the various chemical species of13N. The procedure developed was applied to the deuteron activation analysis of carbon in carbon-doped and undoped gallium arsenides. It took 30 minutes from the end of irradiation to the start of the radioactivity measurement. The detection limit of carbon in gallium arsenide was as low as 1 ppb.

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