共查询到20条相似文献,搜索用时 15 毫秒
1.
P. M. Pollard J. W. McMillan D. J. Malcolme-Lawes 《Journal of Radioanalytical and Nuclear Chemistry》1982,70(1-2):349-370
Sensitive and selective nuclear reaction methods have been sought for the nuclear microprobe measurement of the spatial distributions
of13C and13C/12C ratios. The13C(α, n)16O reaction, with neutron detection, is the most selective for13C, and has a sensitivity of ca. 100 ppm. The reactions13C(d, p)14C and12C(d, p)13C, with proton detection, are the most sensitive for the simultaneous measurement of13C and12C, with detection limits of 30 and 2 ppm respectively. Less sensitive alternative reaction pairs are;13C(3He, p)15N and12C(3He, p)14N;13C(d, nγ)14N and12C(d, pγ)13C;13C(3He, pγ)15N and12C(3He, pγ)14N. The conditions governing their use, particularly light element interferences, are detailed. 相似文献
2.
Thick-target yield of γ-rays emitted in the reactions14N(p,p′γ1)14N and15N(p,αγ1)12C were measured as a function of bombarding energy in order to select the conditions favoring the employment of these reactions
in nitrogen isotopic analysis. The applicability of these reactions in the determination of relative as well as absolute nitrogen
isotopic abundances was demonstrated at 4.3 MeV bombarding energy.
Supported in part by the International Atomic Energy Agency, Vienna, Austria. 相似文献
3.
O. Dersch A. Zouine F. Rauch J. E. Ericson 《Analytical and bioanalytical chemistry》1997,358(1-2):217-219
Diffusion of water into quartz was studied by measuring H and 18O concentration profiles in surface layers of quartz samples treated hydrothermally in the range of 125° C to 200° C. Sample
surfaces were orientated normal to the c-axis. The measurements were performed using the nuclear reactions 1H(15N,αγ)12C and 18O(p,α)15N. The diffusion profiles have widths of up to 500 nm. Diffusion rate constants derived from the profiles are in the range
of 10–15 cm2/s to 10–18 cm2/s and show a distinct temperature dependence, yielding a rough estimate of about 60 kJ/mole for the activation energy.
Received: 24 June 1996 / Revised: 20 January 1997 / Accepted: 22 January 1997 相似文献
4.
J. M. Calvert D. G. Lees D. J. Derry D. Barnes 《Journal of Radioanalytical and Nuclear Chemistry》1972,12(2):271-275
The various nuclear techniques which have been used to study oxygen self-diffusion in oxides are discussed. Results are given
for measurements using resonance capture in the18O(p, α)15N and18O(p, γ)19F reactions and the different techniques are compared. 相似文献
5.
I. S. Giles C. Olivier M. Peisach 《Journal of Radioanalytical and Nuclear Chemistry》1977,37(1):141-154
A survey of the possibilities of analysis by alpha-induced prompt gamma-ray spectrometry is reported for 57 elements at a
bombarding energy of 5 MeV. Additional data obtained at 11 and 16 MeV are given. Interference-free sensitivities are presented.
The use of the position sensitive detector is introduced to overcome problems such as occur in prompt alpha spectrometry from
(p, α) reactions. The technique is illustrated by studies on the reaction19F(p, α)16O and severely tested for boron analysis using the reaction11B(p, α)8Be and measuring the α0 and α1 groups. 相似文献
6.
Experimental data are presented for comparison of the determination of oxygen by the16O(3He, p)18F,16O(3He, α)15O and18O(p, α)15N prompt nuclear reactions, and of their use in the lattice location, by the ion-channelling technique, of oxygen atoms in
single crystal targets of elements such as niobium, where oxygen contents of ≈0.1 atomic % or more can be obtained. Both reaction
cross-sections and lattice-defect production rates are considered in the comparison. Details are given of an arrangement for
automatic crystallographic angular scanning of nuclear reaction and backscattering yields in channelling/lattice location
measurements. 相似文献
7.
Target purification of Sα is carried out by distillation at 444±2 °C under N atmosphere and diluting the vapors in CS2. The solution is filtered through fiberglass, Teflon and cellulose to obtain Sα by CS2 evaporation. Once 30 g of this target are irradiated with fast neutron fluxes from 4.5 to 7.4·1012 n·cm−2s−1 from 6 to 12 hours, the nuclear reaction 32S(n,p)32P takes place. So, the irradiated Sα sample is placed in a Pyrex container situated inside a furnace as the most important piece of equipment in one aluminum
and Lucite glove box. The distillation of irradiated sulfur takes place at 444±2 °C under N atmosphere during 1–2 hours. The
vapors are connected to a sulfur diluter containing 20% CS2 aqueous solution, followed by an activated carbon filter and the two similar additional sulfur diluters. Once cooled, the
distillation chamber keeps the radioactive, carrier-free 32P stuck to the wall. Then 25–50 ml of 0.1N HCl acid was injected by suction and heated again at 110±2 °C during 1 hour. The
corresponding chemical reaction takes place and the labeled H3
32PO4 solution is produced. In such a way, industrial production of 32P labeled molecules has started in Mexico, with an initial production of 3700–5550 MBq per week. 相似文献
8.
J. P. Thomas M. Fallavier J. M. Mackowski C. Pijolat J. Tousset M. Wehr 《Journal of Radioanalytical and Nuclear Chemistry》1980,55(2):427-443
A review is presented summarizing the specific nuclear microanalysis methods applied in our laboratory to study amorphous
semiconductor thin films. For backscattering, ∼3 MeV Li ions are applicable when depth resolution and sensitivity are required
while up to 8 MeV α-particles allow larger depths to be probed and elemental interferences to be solved. These features are
predominant for diffusion studies between metal electrodes and chalcogenide films. On the other hand hydrogen profiling using
the1H(1 5N, αψ) resonant nuclear reactions is described and analytical problems associated with its use are discussed. Applications
to the elaboration conditions of hydrogenated (a)Si is developed.
Work supported by C.N.R.S. (A.T.P. Materiaux 2726 and Photovoltaique A 651 3865) and the C.E.A.—D.A.M. (contract No 1350) 相似文献
9.
T. G. Sobolevskii I. S. Prasolov G. M. Rodchenkov 《Journal of Analytical Chemistry》2010,65(8):825-832
A procedure that makes it possible to establish the origin of endogenous steroids present in human urine by the determination
of the 13C/12C carbon isotope ratio is described. A combination of solid-phase and liquid-liquid extraction, as well as semipreparative
liquid chromatography, was used to separate fractions containing testosterone, 5α- and 5β-androstane-3α, 17β-diols, androsterone,
ethiocholanolone, 5β-pregnane-3α, 20S-diol, and 16(5α)-androstene-3α-ol. More than 100 samples were analyzed by gas chromatography coupled with isotope mass spectrometry.
The resulting values of 13C/12C were statistically processed, and the ranges required for the interpretation of the results were found. The procedure was
certified and accredited in accordance with ISO 17025 requirements. 相似文献
10.
Z. Janout S. Pospíšil M. Vobecký 《Journal of Radioanalytical and Nuclear Chemistry》1980,56(1-2):71-81
A Doppler broadening is described of the 4438 keV spectral gamma-line observed by means of a Ge(Li) detector during the deexcitation
of nuclei of12C in an inelastic scattering12C(n, n′γ)12C using an241Am−Be source as well as during the reaction9Be(α, nγ)12C taking place in the Am−Be source. The FWHM of the spectral line is equal to (90±4) keV in the latter reaction and (64±8)
keV in the former process. Experimental values agree well with theoretical ones.
Presented at the Instrumental Activation Analysis Conference, IAA 79, June 4–8, 1979, Klučenice, Czechoslovakia. 相似文献
11.
A. Ait Haddou M. Berrada G. Paić 《Journal of Radioanalytical and Nuclear Chemistry》1986,102(1):159-175
The yield and average cross section for the reactions11B(p, n)11C,12C(p, )13N,13C(p, n)13N,
12
12
C(d, n)13N,14N(p, )11C,16O(p, )13N,16O(d, n)17F,16O(t, n)18F, and18O(p, n)18F have been measured in different compounds. The charged particles were created in the samples themselves either through recoil by scattering of 14 MeV neutrons off hydrogen and deuterium, or by the (n, t) reaction on6Li using thermal neutrons. The yields of reactions12C(d, n);16O(p, );16O(t, n) and18O(p, n) have been measured using proton, deuteron and triton spectra generated by 14 MeV neutrons in the reactions D(n, p)2n;6Li(n, d);7Li(n, d) and10B(n, d);7Li(n, t) and10B(n, t), respectively. 相似文献
12.
Thick targets (mica) and thin hydrogen layers obtained by ionic implantation of protons in silica are used to establish the
excitation function of the nuclear resonant reaction1H (15N, α γ)12C. Two main resonances in the energy gap explored were observed. Their FWHM and the cross section at ER are specified. The experimental conditions required and the performances allowed, using this reaction to determine hydrogen
depth profiles in the near surface region of solids, are presented. Examples concerning borosilicates, leached in aqueous
medium, are given.
相似文献
13.
Andreas Markwitz Geoffrey Vaughan White William Joseph Trompetter Ian William Murray Brown 《Mikrochimica acta》2001,137(1-2):49-56
Thin SiO2 layers were produced by thermal oxidation of Si wafer material. To study the effect of nitridation on the oxide layers, the
specimens were nitrided in a furnace at high temperature. Non-destructive ion beam analysis was performed to determine changes
in the elemental concentrations and depth profiles of the major components. In particular, N and O concentrations were measured
using the non-resonant nuclear reactions 14N(d, α)12C and 16O(d, p)17O, respectively. To obtain depth profiles of the as-prepared and nitrided specimens, the samples were measured with RBS and
heavy ion elastic recoil detection analysis. The ion beam analyses revealed an increase in thickness of the SiO2 layers with temperature. The specimens nitrided at 1200 °C were almost free of N. Surface topology investigations with scanning
electron microscopy revealed concentric annular artificial patterns at the surfaces. In the centre of the pattern, only silicon
was measured. Additionally, a band consisting of Si, O, and N surrounding the pattern was discovered. The findings are in
agreement with specimens prepared at higher temperatures.
Received June 19, 2000. Revision December 9, 2000. 相似文献
14.
W. W. Osterhage 《Journal of Radioanalytical and Nuclear Chemistry》1980,56(1-2):267-275
A compilation of the cross sections (n, p), (n, n′ p), (n, α) (n, n′ α) and (n,3He) for93Nb,92,95,96,97,98,100Mo by 14 MeV neutrons is presented in the form of a table containing the results of nearly 70 different measurements, mainly
obtained by activation analysis. Brief assessments of the experimental methods and the data status are given. 相似文献
15.
V. W. Pike M. N. Eakins R. M. Allan A. P. Selwyn 《Journal of Radioanalytical and Nuclear Chemistry》1981,64(1-2):291-297
Methods have been developed for the labelling of acetate and palmitic acid with the positron-emitting radionuclide,11C (T=20.4 min). Labelling was achieved via carbonation of the appropriate alkyl magnesium bromide (methyl magnesium bromide
or n-pentadecyl magnesium bromide) with11C-labelled carbon dioxide produced by the14N(p, α)11C nuclear reaction. The radiochemical yield and speed of each method of labelling are such that a radiochemically pure product
is obtained in injectable form and in activity (>10 mCi) suitable for the study of myocardial metabolism by emission-computerised
axial tomography. High pressure liquid chromatography and thin layer chromatography were used to assess the radiochemical
purity of each radiopharmaceutical. The specific activity of11C-labelled acetate was estimated by an enzymic procedure to be greater than 0.5 Ci/μmole. 相似文献
16.
G. Sugihara A. A. Nakamura T. -H. Nakashima Y. -I. Araki T. Okano M. Fujiwara 《Colloid and polymer science》1997,275(8):790-796
For a sodium salt of α-sulfonatomyristic acid methyl ester (14SFNa), one of the α-SFMe series surfactants, the differential
conductivity (∂κ/∂C)
T
,
P
vs. square root of concentration (√C) was employed in order to determine not only CMC but also the limiting molar conductance (Λ0) and the molar conductance of micellar species (ΛM).
Based on the data of the degree of counterion binding to micelles (β) determined previously at different temperatures ranging
15–50 °C at every 5 °C, the experimental values of the degree of dissociation (ionization) of a micelle (αEX) were calculated by regarding as αEX=1−β. The ratio ΛM/Λ0 corresponding to the ratio of slopes below and above CMC in the curve of specific conductivity (κ) vs. concentration (C), which has been often assumed to be the degree of ionization of micelles (α), was compared with the present αEX. However, the ratio ΛM/Λ0 (=α) was found to have a correlationship with αEX (=1−β) as αEX≈0.40×(ΛM/Λ0), or strictly, αEX=0.40 (ΛM/Λ0)+0.08, indicating that the simple ratio of the slopes below and above CMC in κ vs. C curve is not true for αEX=1−β. On the other hand, the method proposed by Evans gave a value closer to αEX compared with the simple ratio.
Received: 17 September 1996 Accepted: 8 April 1997 相似文献
17.
Nuclear reactions induced on light elements by low energy deuterons are investigated. Differential cross-sections for10B(d, β0)8Be,10B(d, β1)8Be,12C(d, p0)13C,14N(d, β0)12C,14N(d, β1)12C,16O(d, p0)17O,16O(d, p1)17O and16O(d, β0)14N reactions are measured between 0.5 and 3 MeV at an observation angle of 135° with respect to the incident beam. Possible
application of these reactions to the measurement of surface concentration is considered—Special emphasis was given on nitrogen
determination in order to study nitrogen concentration in industrial glasses. Surface nitrogen repartition on glass, origin
of nitrogen, influence of oxidizing and reducing conditions and glass structure are discussed. 相似文献
18.
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
19.
R. Pretorius P. P. Coetze M. Peisach 《Journal of Radioanalytical and Nuclear Chemistry》1973,16(2):551-558
The coincident measurement of both nuclear products at their complementary angles was used to determine6Li by the reactions6Li(d, α)4He and6Li(p, α)3He, and7Li by the reaction7Li(p, α)4He. Elemental lithium was determined in natural samples or samples of known isotopic composition. Isotopic analyses could
be carried out over the entire range from 0 to 100 atom% with a relative standard deviation of about 4%. The CMCP technique
is highly specific and effectively eliminates interference and background. 相似文献
20.
The use, for analysis, of prompt gamma-rays excited by 5 MeV alpha-particles from the reactions19F(α,α′γ)19F,19F(α, nγ)22Na and19F(α, pγ)22NE, was studied. The precision of the analyses depended on the gamma-ray energy used for the measurement. Relative standard
deviations were ±1.8, ±0.9 and ±1.3% using the 110-, 197- or 1275 keV gamma-rays. The method was tested with N. I. M. standard
materials of calcium fluoride and fluorspar, and was used as a rapid method for the determination of fluorine in cements. 相似文献