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A procedure is outlined for a programmable spin-free configuration-interaction (CI ) study in molecules using single-parameter alternant molecular orbitals for generating various configurations. The configurations were chosen to form bases for the irreducible representation {2N/2–2, 12S} of the general linear group GL(n). Using a transformation to biorthogonal space the CI matrix elements of a spin-free Hamiltonian were generated. The procedure has been used to obtain the π-electron energies for the 3,1Ag and 3,1Bu states of cis- and trans-butadiene. 相似文献
24.
Summary The mixed ligand complex, [Fe(Phen)2(N3)2] can be extracted into nitrobenzene giving a molar absorptivity of 16750 at 510 nm. This is the basis of a photometric method for iron which may be either in the trivalent or bivalent state. The new method is free from interference from a number of substances and is more sensitive than the ferroin method.
Zusammenfassung Der Eisen-Phenanthrolin-Azid-Mischkomplex [Fe(Phen)2(N3)2] ist mit Nitrobenzol extrahierbar und gibt bei 510 nm eine molare Absorption von 16750. Darauf läßt sich eine photometrische Bestimmungsmethode für zweioder dreiwertiges Eisen begründen. Diese wird von vielen Stoffen nicht gestört und ist empfindlicher als die Ferroinmethode.相似文献
25.
T. Suryanarayana Murthy D. V. N. Sarma 《Fresenius' Journal of Analytical Chemistry》1958,161(2):114-115
Summary A method for separation of thorium from rare earths in monazite based on the difference of stability of EDTA complexes towards oxine is described. 相似文献
26.
Sumit Bhaduri Krishna R. Sarma Bikshandarkovil A. Narayan 《Transition Metal Chemistry》1981,6(4):206-210
Summary Four-coordinate nickel nitrosyl complexes of the general formula Ni(NO)X(Dppe) (Dppe=Ph2PCH2CH2PPh2) have been prepared byin situ formation of Ni(NO2)X(Dppe), (X= Cl, Br, I or SCN) followed by reduction with triphenylphosphine, or carbon monoxide, and/or DMF. Oxygenation of the nitrosyl complexes gives the corresponding nitro products and as indicated by u.v.-vis spectroscopy involves formation of an intermediate. The oxygenation rate increases markedly in the presence of light or of a catalytic amount of benzoyl peroxide and a tentative explanation is offered for these observations. Ionic adducts are formed in reactions between the nitrosyl complexes and donor molecules.Paper presented in part at the XXth ICCC Conference. 相似文献
27.
Dutta D Sarma TK Chowdhury D Chattopadhyay A 《Journal of colloid and interface science》2005,283(1):153-159
In this paper we report a new idea for synthesizing polyaniline in an ordinary filter paper. The synthesis was carried out by a process in which aqueous acidic aniline solution and the oxidizing agent H(2)O(2) was added to the paper drop by drop and in sequence. Uniform polymerization could be obtained with the addition of reagents in either sequence. The polymer formation led to a green coloration of the paper. Formation of the emeraldine salt of polyaniline was confirmed by UV-vis and FTIR spectroscopy. Scanning electron microscopic measurements were made for surface characterization of the polymer formed in the paper. The same paper was used as a sensor for ammonia in vapor and in solution, for acid and base as well as endpoint indication, and also to filter acids and bases. We found that, using the polymer-containing paper, ammonia concentrations in a solution as low as 14 ppm could be measured. 相似文献
28.
We report the study of complex and unexpected dependencies of nanocrystal size as well as nanocrystal-size distribution on various reaction parameters in the synthesis of ZnO nanocrystals using poly(vinyl pyrollidone) (PVP) as a capping agent. This method establishes a qualitatively different growth mechanism to the anticipated Ostwald ripening behavior. The study of size-distribution kinetics and an understanding of the observed non-monotonic behaviors provides a route to rational synthesis. We used a simple, but accurate, approach to estimate the size-distribution function of nanocrystals from the UV-absorption spectrum. Our results demonstrate the accuracy and generality of this approach, and we also illustrate its application to various semiconducting nanocrystals, such as ZnO, ZnS, and CdSe, over a wide size range (1.8-5.3 nm). 相似文献
29.
Chen CH Hwang BJ Wang GR Sarma LS Tang MT Liu DG Lee JF 《The journal of physical chemistry. B》2005,109(46):21566-21575
We report in situ X-ray absorption spectroscopy (XAS) investigations on the formation of palladium-platinum (Pd/Pt) bimetallic clusters at the early stage within the water-in-oil microemulsion system of water/AOT/n-heptane. The reduction of palladium and platinum ions and the formation of corresponding clusters are monitored as a function of dosage of reducing agent, hydrazine (N(2)H(5)OH). Upon successive addition of the reducing agent, hydrazine (N(2)H(5)OH), five distinguishable steps are observed in the formation process of Pd/Pt clusters at the early stage. Both in situ X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analysis for both the Pd K-edge and Pt L(III)-edge revealed the formation of Pd/Pt bimetallic clusters. A corresponding structural model is proposed for each step to provide a detailed insight into the nucleation and growth mechanism of Pd/Pt bimetallic clusters. We also discussed the atomic distribution of Pd and Pt atoms in Pd/Pt bimetallic clusters based on the calculated XAS structural parameters. 相似文献
30.
Depending on the pH, 1-(1-indolinyl)-3-aryltriazenes (I) or 5-arylazoindolines (II) are formed in the reaction of indoline with aryldiazonium salts. In acid media, I are rearranged to II. The dehydrogenation of I or II with chloranil gives 5-arylazoindoles.See [1] for communication LXXVI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 648–651, May, 1972. 相似文献