共查询到20条相似文献,搜索用时 15 毫秒
1.
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.
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2.
Ph. Albert J. Blouri Ch. Cleyrergue N. Deschamps J. Le Héricy 《Journal of Radioanalytical and Nuclear Chemistry》1968,1(4):297-311
The determination of sulphur and phosphor by means of activation analysis in high purity aluminium and magnesium is described. The irradiations were performed both with thermal and with fast neutrons. A detailed procedure is given and errors not considered so far are discussed. 相似文献
3.
A spectrophotometric study of the cobalt-β-nitroso-α-naphthol complex between 200 and 350 nm showed the existence of a very sensitive absorption maximum at 308 nm. Utilization of this wavelength allows cobalt in the range 10-6–10-5 g to be determined with good precision. The proposed method is very suitable for the determination of cobalt in high-purity iron. 相似文献
4.
Résumé Dans le cadre des recherches effectuées à l'Ecole Nationale Supérieure des Mines de Saint-Etienne sur les métaux de très haute
pureté, il était très important de pouvoir conna?tre avec précision la concentration de chaque élément étranger présent dans
ces métaux. Nous montrons comment un laboratoire, situé loin des Centres Atomiques, peut employer l'analyse par radioactivation.
L'application principale a été l'analyse du fer très pur pour laquelle nous avons mis au point une nouvelle méthode simple
et rapide utilisant l'extraction à l'acétate de butyle qui permet une séparation sélective et quantitative de la matrice fer. 相似文献
5.
Isonitrosomalonylguanidine reacts with iron salts in acid medium (pH ca. 6) ; or in basic medium (pH ca. 9), giving a blue color. This reaction is the basis of a new method for the determination of iron. in aluminium alloys (in acid medium) or in zincs (in acid medium or in basic medium) for the weakest contents. Concerning the determination of cobalt in steels, bromine can be used instead of nitric acid, in order to remove the excess of reagent. 相似文献
6.
M. Treuil H. Jaffrezic N. Deschamps C. Derre F. Guichard J. L. Joron B. Pelletier S. Novotny C. Courtois 《Journal of Radioanalytical and Nuclear Chemistry》1973,18(1-2):55-68
Résumé Pour utiliser au mieux les possibilités de l'analyse par activation et de la spectrométrie γ à l'aide des détecteurs à semi-conducteurs,
nous proposons des schémas de séparations rapides qui permettent d'effectuer les analyses de routine des lanthanides, du scandium,
du chrome, du manganèse, du cobalt, du cuivre et du zinc, dans la plupart des minéraux et des roches avec une précision comprise
entre 3 et 10%. La méthode a été appliquée à une grande variété d'échantillons et testée sur des standards. Nous montrons
par quelques exemples tout son intérêt dans les études géochimiques systématiques des éléments de transition. 相似文献
7.
《Materials Chemistry》1982,7(1):35-42
Electrical measurements of corrosion scales growing on copper and nickel in SO2O2 atmospheres show a different behaviour for both metals. For copper, the electrical conductivity indicates that Cu2S is formed in pure SO2 and Cu2O in SO2O2 mixtures (ratio PSO2/PO2 = 105). In the case of nickel, the high conductivity of product scales in atmospheres containing pure SO2 or SO2O2 is consistent with an interconnected Ni3S2 phase in NiO. In all cases the corrosion scales have a positive Seebeck coefficient. 相似文献
8.
J.F. Muller J.M. Magar D. Cagniant J.M. Mouchot J. Grimblot J.P. Bonnelle 《Journal of organometallic chemistry》1981,205(3):329-341
The complexes obtained by the action of vanadyl ethylate on some open-structured ligands (type 1,4,8,11-tetrathiaundecane TTU) are characterized by mass spectroscopy with laser impact (LAMMA) and by photoelectron spectroscopy ESCA. The results are compared with those obtained from some reference compounds and several fractions of asphaltenes. 相似文献
9.
F. Nordmann G. Tinelli Ch. Engelmann 《Journal of Radioanalytical and Nuclear Chemistry》1973,17(1-2):255-273
Résumé On expose les méthodes mises au point pour déterminer les très faibles teneurs en carbone et oxygène dans le sodium ou le
césium. Ces deux éléments sont en effet do sables respectivement par les réactions nucléaires suivantes:12C (γ, n)11C et16O(γ, n)15O. Les procédés de séparation chimique utilisés pour séparer carbone 11 et oxygène 15 sont décrits. L'influence des réactions
nucléaires compétitives produisant ces mêmes radioisotopes à partir des autres impuretés ou de la matrice dans le cas du sodium
est discutée. On donne de nombreux exemples d'applications. Ces méthodes ont en particulier permis de déterminer des teneurs
en oxygène de quelques 10−1 μg/g, et en carbone d'environ 1 μg/g, dans le sodium. Les concentrations trouvées dans le césium sont plus élevées. On compare
les résultats avec ceux obtenus par d'autres méthodes. 相似文献
10.
A method is described for titrimetric determination of iron, uranium or plutonium in nitric acid media. The element is reduced with titanium(III) solution in presence of sulfamic acid, and titrated with cerium(IV) solution. Precautions normally taken for nitric acid media are unnecessary. The method is rapid and precise and is readily applicable to determinations of plutonium or irradiated uranium. 相似文献
11.
12.
The complexing of Li+ by two new ethers has been studied by spectrophotometry. The strength of the complexing has been checked by tacticity analysis of PMMA obtained in the presence of the two (Li+, ether) systems. A weak (Li+, ether) complex does not affect the isotactic character of the anionic propagation in a hydrocarbon medium but, if the donor is a crown ether, Li+ is strongly complexed and the propagation becomes syndiotactic. 相似文献
13.
J. Kwinta J. Demange J. J. Michel 《Journal of Radioanalytical and Nuclear Chemistry》1980,55(2):233-252
The distribution of uranium in two different rock species: basalt from the Fangataufa atoll (located in Polynesia) and granit
from the Hoggar mountains (located in Sahara) was studied by the fission track method. The two distributions observed appear
quite different: uranium is uniformly distributed in the vitrous part of the basalt while in granit it is located on the intergranular
joints. Applying the sampling model proposed by A. D. WILSON to the observed distributions of uranium, the weight of the analytical
sample corresponding to a required sampling error can be estimated. Results show that representative sample weights of the
bulk powdered material, as usually obtained by milling, are about some tenths of milligrams for basalt and more than the grams
for granit (for uranium analysis). So, in trace element analysis, the sampling error could be more important than the analytical
one. This fact could explain the relatively poor accuracy of trace determinations in rock samples (including the reference
samples).
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14.
The 837 keV resonance is used for the rapid and non-destructive determination of the gradient of fluorine on the surface of metallic samples. The precise yield curve of this resonance for thick target and the experimental sensitivity of the method have been determined. With this method less than 5·10?4 μg·cm?2 fluorine content can be measured. The resolution is of the order of 1000 Å in aluminium and the concentration profiles can be measured to the depth of 1 μm. The time requirement of a surface analysis is 15–30 min, and 2–3 hrs of a gradient measurement. In addition, this method is simpler and more sensitive than the detection of the 1350 keV alpha-particles from the19F(p, αo)16O reaction. 相似文献
15.
《Journal of organometallic chemistry》1987,326(2):289-297
The new chiral aminodiphosphinite ligands are readily prepared from chiral amino acids. These compounds were characterized by 13C and 31P NMR spectroscopy and their behaviour as homogeneous catalysts was investigated in the linear dimerization of butadiene. 相似文献
16.
《Journal of fluorine chemistry》1988,39(1):1-16
(F-alkyl-2 ethyl) triphenylcarboethoxymethylenephosphorane ylides show two different sets of ethyl protons in their 1H NMR spectra. We have formulated a hypothesis, and proved it by X ray diffraction, that this phenomena in solution was related to hindered rotation. Two rotational isomers were present in equilibrium at low temperature. Each of them could exist as a mesomeric structure. Further, the complete structure of this type of compound was established and the main results are discussed. 相似文献
17.
N.M.R.13C peak assignments were established for each diastereoisomeric ketal form of norbornanone (±), or norbornenone (±). This method offers an attractive route for the determination of the optical purity of these ketones. 相似文献
18.
Résumé Nous montrons que l'activation par les protons de 11 MeV permet le dosage non destructif de traces d'impuretés dans des échantillons
d'Argent, d'Aluminium et de Cobalt. Nous avons pour le moment étudié le dosage de 30 éléments dans Al et Co et de 24 dans
Ag. Nous avons choisi les protons car ces particules sont les seules qui permettent d'effectuer un dosage non destructif dans
Ag et Co, au niveau des traces sans interférence, et ceci pour de nombreux éléments. Le cas de l'aluminium a été étudié, bien
que les neutrons puissent ici être utilisés pour l'analyse non destructive car l'activation dans les protons permet de doser
facilement des éléments autres que ceux dosés en irradiant dans les neutrons. Ces premiers résultats nous conduisent à penser
que l'activation dans les protons sera très employée dans les cas où l'activation neutronique est en difficulté (exemple de
Ag, Co, Ir, HgTe, AsGa, terres rares, etc.). 相似文献
19.
20.
The changes in Gibbs energy, enthalpy, and entropy for the protonation of phenylalanine anion (L) and for the formation of complexes ML+ and ML2 (M = Cu2+ or Co2+) are reported for I = 1 M (Na)Cl at 25°C. The results are compared with those of other workers. The Gibbs energy changes are determined from corresponding formation constants (or protonation constants) previously measured by potentiometry. The enthalpy changes are measured by calorimetry. Two experimental systems for carrying out solution calorimetry are described. 相似文献