共查询到20条相似文献,搜索用时 31 毫秒
1.
S. M. Kormali W. D. James J. E. Poland E. A. Schweikert 《Journal of Radioanalytical and Nuclear Chemistry》1985,91(1):179-183
The application of charged particle activation analysis to the determination of phosphorus in a variety of sample materials is discussed. The activity produced via the31P(, n)34mCl reaction is quantitated either nondestructively or using postirradiation radiochemical separations depending on the characteristics of the sample matrices. Corrections which are necessary for the determination of phosphorus in pure tantalum metal due to spectral interferences are discussed. 相似文献
2.
M. A. Arribére S. Ribeiro Guevara A. J. Kestelman I. M. Cohen 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(1):25-31
The feasibility of validating data obtained in the determination of chlorine, potassium, and calcium by neutron capture activation
analysis, through their determination using threshold reactions has been studied. To this purpose the authors experimentally
determined the following fission neutron spectrum averaged cross sections (in mb):37Cl(n,p)37S, 0.234±0.015;41K(n,α)38Cl, 0.740±0.044;42Ca(n,p)42K, 3.09±0.22;43Ca(n,p)43K, 2.27±0.12;44Ca(n,p)44K, 0.074±0.013. The application of these values to the analysis of some reference materials are presented. Also, the problem
of mutual interferences has been addressed for the following pairs:36S(n,Γ)37S and37Cl(n,p)37S;37Cl(n,Γ)38Cl and41K(n,α)38Cl;41K(n,ψ)42K and42Ca(n,p)42K. 相似文献
3.
Ph. Albert J. Blouri Ch. Cleyrergue N. Deschamps J. Le Hericy 《Journal of Radioanalytical and Nuclear Chemistry》1968,1(5):389-396
The analytical procedure for the determination of sulfur in copper by activation with thermal neutrons is given. The purifications
necessary to obtain a radiochemically pure precipitate of baryum sulphate are described. The occurrence of some discrepant
values in the determinations led to the observation, for the first time, of abnormally high contents of35S* at a relatively important depth in the samples of irradiated copper (as deep as about 300 μ). Therefore it is necessary to
etch the samples to a depth of 300 μ at least on each surface, before doing the chemical separations. Owing to the great influence
of the reaction35Cl(n,p)35S*, the determination of sulfur by thermal neutrons is only possible at contents higher than 10−6, even if the chlorine concentration is very low (2·10−8 Cl introduces a correction in terms of sulfur of the order of 10−6). For sulfur contents lower than 10−6, the determination is made by irradiation in fast neutrons. The analytical procedure is described and the corrections in
the presence of phosphorus and chlorine are discussed. At contents of the order of 10−8, the corrections are very small and the determination of some 10−7 of sulfur is easy. Finally, the determination of phosphorus in copper by activation in thermal neutrons is given. The chemical
separations are the same as in the preceding case. Contents of the order of 10−8 phosphorus are determined without difficulty. The results of the determination of sulfur and phosphorus in many samples of
copper are indicated: OFHC copper, High Purity copper (99.999%) and different samples of zone refined copper prepared at the
Vitry’s Laboratory.
相似文献
4.
R. Van Grieken A. Speecke J. Hoste 《Journal of Radioanalytical and Nuclear Chemistry》1970,6(2):385-398
A fast (10 min), non-destructive simultaneous determination of silicon and phosphorus in cast iron and steel by 14 MeV neutron
activation was developed. The 1.78 MeV28Al activity (T=2.24 min) induced by the reaction28Si(n, p)28Al is counted on a NaI(Tl) detector. Two measurements are made to correct for the 1.81 MeV56Mn activity (T=2.58 hr) from the iron matrix. However,28Al is also produced via31P(n, α)28Al. By (n, 2n) reaction, phosphorus yields also30P (T=2.6 min), the 0.511 MeV annihilation radiation of which is counted by two opposite NaI(Tl) detectors in coincidence.
Again, two successive coincidence measurements are carried out in order to take into account the53Fe activity (β+; T=8.9 min) from54Fe(n, 2n)53Fe. The28Al measurement is appropriately corrected via the computed phosphorus content. An oxygen flux monitor was used to normalize
to the same flux. Nuclear interferences have been examined. Special attention has been paid to the presence of copper. The
standard deviation for phosphorus being as high as ca. 0.09% P for a single determination, this technique can only be practical
as an independent phosphorus analysis for high phosphorus cast irons. The precision on the28Al measurement is 5% relative for 0.2% Si and 2.5% above 1% Si.
Aspirant of the N.F.W.O. 相似文献
5.
Silicon as silicon dioxide in iron and steel-making slags and fluorspars was analyzed by 14 MeV neutron activation high-resolution
γ-ray spectrometry. Silicon was detected by measuring the 1.78 MeV γ-ray of28Al, the product of the28Si(n, p) reaction, using a 30 cm3 coaxial Ge(Li) detector. A modified TPA method was used for the calculation.28Al is also produced from phosphorus by the31P(n,α) reaction, and from aluminium by the27Al(n,γ) reaction. The contribution from the former reaction could be corrected experimentally when the P2O5 content of the sample was known, while the latter reaction could be neglected in this neutron energy region. The experimental
correction coefficient for phosphorus agreed well with the theoretical value calculated from the nuclear properties of silicon
and phosphorus. Yields of28Al from SiO2, P2O5 and Al2O3 of the same weight percentages were calculated as 1, 0.426 (experimentally 0.44) and 0.0022, respectively. The results of
this method agreed well with the results of the usual chemical methods. The limit of detection of SiO2 in iron and steel-making slags and fluorspars was calculated as 0.07%. The coefficient of variation of repeated experiments
was compared with the statistical one. 相似文献
6.
Ph. Albert J. Blouri Ch. Cleyrergue N. Deschamps J. Le Hericy 《Journal of Radioanalytical and Nuclear Chemistry》1968,1(6):431-441
The chemical separation of sulphur and phosphorus from pure iron and nickel, is described. Sulphur has been determined first
by irradiation in fast neutrons, then by irradiation in mixed fast and thermal neutrons. The two methods gave two different
results; so, we were led to point out the same phenomenon asJ. Le Hericy had already pointed out for the determination of sulphur in copper. We found that the abnormal amounts of sulphur came from
external contamination with chlorine since sulphur is then produced by the35Cl(n, p)35S reaction. The diffusion of35S atoms (produced on the edge of the samples) explains that the concentration of sulphur decreases from the edge to the middle
of the sample. We prepared samples of iron and nickel, artificially covered with ammonium chloride, and we studied the apparent
concentration of sulphur as a function of the depth in these samples. Our experiences pointed out that the contamination in
sulphur yielded by the (n, p) reaction, reaches very quickly the middle of the samples. This phenomenon limits the determination
of sulphur by the34S(n, γ)35S reaction, in nickel and iron.
相似文献
7.
T. Sekine M. Konishi H. Kudo K. Tagami S. Uchida 《Journal of Radioanalytical and Nuclear Chemistry》1999,239(3):483-487
A95mTc tracer with an excellent quality was prepared by a simple sublimation method after α-bombardment of niobium metal. Technetium-95m
produced by the93Nb(α,2n)95mTc reaction was separated from the niobium targets in a quartz tube by heating at 1100°C in an oxygen gas flow. Technetium-95m
sublimed as an oxide was deposited on the inner wall of the quartz tube outside an electric furnace, and then collected as
a pertechnetate solution by washing with water. The ICP-MS analysis of the95mTc solution revealed its excellent quality, compared to a95mTc solution prepared from the same targets through a wet chemical separation method and a commercial95mTc solution. With this tracer, the precision of ICP-MS analysis of99Tc in environmental samples are highly improved. 相似文献
8.
G. K. Semin E. N. Tsvetkov T. L. Khotsyanova E. V. Bryukhova 《Russian Chemical Bulletin》1999,48(5):906-913
Regularities of transmission of the effect of equatorial and axial substituents were established for a number of chlorine-containing
organic compounds of pentatalent phosphorus using35Cl NQR spectra. The field constants of35Cl NQR frequencies of the chlorine atoms participating in the P−Cl bond were estimated for a series of tetrahedral phosphorus
ions. The35Cl NQR frequencies of chlorine atoms in tetracoordinated ions of pentavalent phosphorus and in analogous isoelectronic silicon
compounds are related by a linear dependence.
Deceased
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 915–922, May, 1999. 相似文献
9.
Transuranium nuclides were produced by irradiating a pellet of natural uranium sulfide in the Japan Material Testing Reactor
(JMTR). After irradiation, a successive separation of uranium, plutonium, americium and curium was carried out. The fractional
concentrations of the nuclides238Pu,239Pu,240Pu,241Am,243Am,242Cm and244Cm were determined by α-ray spectrometry, and those of241Pu and242mAm were estimated from the build-up of α-emitting daughters,241Am and242Cm, respectively. As the yield of242Pu was too slight to be detected by α-counting, the neutron activation analysis of the plutonium fraction based on the242Pu(n, γ)243Pu reaction was carried out by γ-ray spectrometry, and it was shown that a few pg of242Pu could be determined. A burn-up of235U was also estimated by neutron activation analysis. The experimental results are compared with the calculated ones. 相似文献
10.
Junhua Luo Chenghu Li Zhenlai Liu Xinxing Wang Rong Liu Li Jiang 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):421-426
Cross-sections for (n,p), (n,α), (n,n′α), (n,t) and (n,2p) reactions have been measured on 139La isotope at the neutron energy 14.8 MeV using the activation technique in combination with high-resolution gamma-ray spectroscopy.
Neutrons were produced via the 3H(d,n)4He reaction using a solid tritium–titanium target. The neutron fluences were determined using the monitor reaction 27Al(n,α)24Na. The neutron energy in this measurement was determined by cross section ratios for the 90Zr(n,2n)89m+gZr and 93Nb(n,2n)92mNb reactions. Data are reported for the following reactions: 139La(n,p)139Ba, 139La(n,α)136Cs, 139La(n,n′α)135mCs, 139La (n,t)137mBa, and 139La(n,2p)138Cs. The cross sections were discussed and compared with experimental data found in the literature, and with the comprehensive
evaluation data in ENDF/B-VII.0, JENDL-3.3, JEFF-3.1/A, and TENDL-2008 libraries. 相似文献
11.
P. K. Sazonov M. M. Shtern Yu. F. Oprunenko I. P. Beletskaya 《Russian Chemical Bulletin》1998,47(8):1532-1536
The13C and19F NMR spectra ofZ- andE-isomers of β-X-substituted α,β-difluorostyrenes (X=F, Cl, CpFe(CO)2, Re(CO)5, Re2(CO)9Na) were studied. Direct and long-range (across 1–5 bonds) spin-spin coupling constants and the (13C−12C) isotope shifts in the19F NMR spectra were determined. The study of the13C satellites in the19F NMR spectra of substituted difluorostyrenes permitted assignment of the13C NMR signals of the vinylic carbon atoms. Similarly, the signals in19F NMR spectra were assigned based on coupling constants of fluorine withipso-carbon. These assignments were found to be in good agreement with the data available from the literature (X=F, Cl). The developed
approach was applied to the elucidation of the structure ofZ−PhCF=CClFe(CO)2Cp.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya. No. 8, pp. 1575–1579, August, 1998. 相似文献
12.
S. Kopta T. Petryna I. Stroński 《Journal of Radioanalytical and Nuclear Chemistry》1972,11(2):189-195
The results of experiments on the preparation of carrier-free lanthanides from some targets irradiated in the U-120 cyclotron
are presented. In the reactions151Eu(α, n)154m,154Tb,151Eu(α, 2n)153Tb,155Gd(α, 2n)157Dy,169Tm(α, n)172Lu and169Tm(α, 2n)171Lu, the isotopes154m,154+153Tb,157Dy and172+171Lu were obtained. These were seaprated by means of ion-exchange chromatography.
Part II: see Ref. 2 相似文献
13.
The MNDO andab initio (Hartree—Fock method, split 6-31G* basis set, full optimization of geometry) calculations for theo- andm-dichlorobenzene molecules have been performed. The populations of the valent p-orbitals of the carbon and chlorine atoms have been analyzed. Estimations of the35Cl NQR frequencies and the asymmetry parameters of the electric field gradient at the35CI nuclei have been made. It was confirmed that these values are not determined by the contribution of the whole valent p-shell, but only by its less diffuse component.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2180–2183, September, 1996. 相似文献
14.
An INAA technique employing beta spectrometry was developed for the determination of phosphorus in polymers. The (n,γ) reaction
on phosphorus produces32P, half-life 14.3 days, a pure beta emitter with end-point energy 1.71 MeV. Polymer samples in the form of powders, films
and pellets are irradiated and then counted with a plastic scintillator. The beta spectrum is corrected for interferences
(especially Sb, Zn and Br which are quantified by gamma spectrometry) and for energy loss in the thick sample. Samples must
also be analyzed for S and Cl which cause nuclear interferences. With an irradiation time of 4 hours at a neutron flux of
5·1011 n·cm−2
s
−1, decay time 10 days and counting time 10 minutes, the sensitivity is 520 counts/μg phosphorus and the detection limit is
typically 2μg/g. 相似文献
15.
J. D. Jones P. B. Kaufman W. L. Rigot 《Journal of Radioanalytical and Nuclear Chemistry》1979,50(1-2):261-275
Silicon has been found to be an essential element for the growth and development of many ecomomically important plants such
as sugarcane, rice, oats, and wheat. A method is described for the quantitative determination of silicon in plant samples.
Measurements were made with two Ge(Li) detectors matched with a multiplexing unit to provide a single amplified signal to
a computerized analyzer system. For those materials containing greater than 0.5 weight percent silicon, the reaction29Si(n, p)29Al (1273 keV) provides a direct measurement of the quantity of silicon provided the irradiation is done in a special boron
nitride capsule to reduce interferences from thermal neutron reactions and a correction is made for the single escape line
from28Al (1268 keV). For lesser quantities of silicon, a technique which utilizes the fast neutron reaction28Si(n, p)28Al is preferred. Corrections for the interference produced by the presence of phosphorus31P(n, α)28Al are made by determining the phosphorus content following the instrumental analysis using a unique application of neutron
activation analysis, i. e., measurement of tungsten in tungstomolybdophosphoric acid produced when molybdate and tungstate
ions are added to dissolved samples of the plant material containing phosphorus. Aluminum, which may also produce an interference
by thermal neutron reaction27Al(n, γ)28Al, is determined directly from the original activation data after subtracting out the effect of the phosphorus. Thus, three
irradiations in the pneumatic sample irradiator are necessary; one short irradiation (1 min) without thermal neutron shielding,
a longer irradiation (6 min) in the boron capsule, and a final irradiation of the tungstomolybdophosphoric acid provide all
data required to accurately determine silicon in plant materials. A computer program has been developed that provides rapid
reduction of the data in final report format. Elements such as sodium, chlorine, calcium, manganese, potassium, and magnesium
extrinsic to the analysis for silicon are also determined by this method. The method has been tested on a large number of
samples and reliable results are obtained with less than 0.2 g of sample.
This work was supported by Grant 533 from the Michigan Memorial—Phoenix Project. 相似文献
16.
M. Berrada M. A. Misdaq P. Thalouarn 《Journal of Radioanalytical and Nuclear Chemistry》1979,54(1-2):361-366
The applicability of 14 MeV neutron activation analysis for the determination of K in beet has been investigated by measuring
the 2.167 MeV gamma-line from the decay of38gK produced in the39K(n, 2n) reaction. Beet samples were treated in different solutions of KCl and HgCl2 to study the diffusion of K+ ions into the beet cells. The contribution of the gamma-line to the measured peak area from38Cl produced in the37Cl(n, γ) reaction was found to be 1%. Results obtained by fast neutron activation analysis and by flame spectrometry have
been compared, and good agreements were found. 相似文献
17.
K. Rössler W. Tornau G. Stöcklin 《Journal of Radioanalytical and Nuclear Chemistry》1974,21(1):199-209
The radioisotopes123I (T=13.3 h) and, potentially,211At(T=7.2 h) find increasing interest for radiopharmaceutical applications in diagnosis and therapy. They were produced via
the122Te(α, 3n)13Xe(α+)13I and the209Bi(α, 2n)211At processes. Fast and efficient separations of carrier-free species obtained from target processing, as well as from classical
or decay-induced synthesis were archieved by means of high-pressure ion-exchange and partition chromatography. Inorganic forms
(X−, XO
3
−
, At+) could be identified and separated on pretreated Aminex A 27 and A 7 resins, and biomolecules such as 5-halodeoxyuridines
and-uracils on Aminex A 25 resins and Merckosorb Si 60 silica. The chromatographic methods can also be used for stability
tests of radiopharmaceuticals in biochemical mixtures, notably physiological fluids. 相似文献
18.
W. D. James W. D. Ehmann C. E. Hamrin L. L. Chyi 《Journal of Radioanalytical and Nuclear Chemistry》1976,32(1):195-205
The feasibility of using fast neutron (14 MeV) activation analysis techniques for the determination of oxygen and nitrogen
in coal has been investigated. Conditions that favor instrumental neutron activation analysis (INAA) include the absence of
problems associated with sample dissolution and the capability of extremely rapid analyses as compared to older techniques
such as the Kjeldahl method for nitrogen. Most previous oxygen determinations have been by difference after major component
analyses. In the present study, oxygen was determined in sized coal and its low temperature ash (LTA) with the difference
representing the organic oxygen content. Both the oxygen and nitrogen analyses employ a multiscaling technique with the former
based on the16O(n, p)16N reaction, while the latter utilizes the annihilation radiation produced by the product of the14N(n, 2n)13N reaction. The high-energy gamma-radiation associated with the decay of16N was essentially free of spectral interferences for coal analysis, although fluorine could cause a primary interference if
the F/O ratio exceeds 0.02. In the nitrogen work, experiments were performed to determine correction factors to account for
the effects of the12C(p, γ)13N and13C(p, n)13N “knock-on” reactions and the39K(n, 2n)38K reaction which produce interfering β+ emitting radionuclides. Data are presented for oxygen in Western Kentucky No. 9 and No. 11 coal and coal ash and for nitrogen
in eleven different coals. 相似文献
19.
A method has been developed for determining silicon in aluminium by fast neutron activation. It is based on the separation
of two gamma lines by a Ge(Li) detector: the 1.73 MeV line from the product of27Al(n, α)24Na and the 1.78 MeV line from the28Si(n, p)28Al reaction. In the case of aluminium-silicon alloys 100 μg silicon can be determined, with an error of 10% in an aluminium
sample of 1 g.
This work was supported in part by the International Atomic Energy Agency. 相似文献
20.
The field constant of the NQR frequency of a chlorine atom (35Cl) in a series of arsenic derivatives [R1R2R3AsCl]+M− was estimated from correlations. The field frequency is ∼41.5±3.5 Hz cm kV−1, which is nearly twice as much as that in analogous phosphorus compounds.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1758–1760, August, 2005. 相似文献