Showing papers by "Indian Association for the Cultivation of Science published in 1985"
TL;DR: It is shown that this theory is equivalent to a propagator formalism in terms of hole- and particle-creation and/or annihilation operators with a modified effective Hamiltonian.
Abstract: A general method for constructing bases for operator manifolds for any propagator, which satisfy ``vacuum annihilation conditions'' (VAC's) is developed. This approach is based on the observation that if the transformation of the unperturbed ground state to the correlated ground state is represented as a rotation in the Fock space, the corresponding rotation induced in the basis of the concerned operator space would generate a basis which satisfies VAC's on the correlated ground state. The associated requirements for the Hermiticity of superoperator Hamiltonian would also be met in this new basis. The proposed method is noniterative in that, once the form of the ground-state function is specified, the expansion of the operator manifold satisfying VAC's on the ground state does not require any iterative readjustment. The resultant propagators in this approach are fully linked. It is shown that this theory is equivalent to a propagator formalism in terms of hole- and particle-creation and/or annihilation operators with a modified effective Hamiltonian. The self-consistent electron and polarization propagators are considered as examples, and their underlying perturbative structures are analyzed. The role of density shift operators and higher-rank operators are discussed.
39 citations
TL;DR: In this paper, the refractive indices ne, no and densities and the dielectric primittivities e∥ and e⊥ of three P-cyano-P-alkylcyclohexanes (PHC-3, PCH-5,PCH-7) have been measured at different temperatures.
Abstract: The refractive indices ne, no and densities and the dielectric primittivities e∥ and e⊥ of three P-cyano-P-alkylcyclohexanes (PHC-3, PCH-5, PCH-7) have been measured at different temperatures. The ...
37 citations
TL;DR: In this article, the rate constants for the excited-state proton transfer reaction of carbazole in aqueous alkaline solution have been determined using picosecond single photon counting.
35 citations
TL;DR: Positron impact ionisation cross sections for helium atoms have been calculated in the energy range 30-150 eV as mentioned in this paper, where the initial state of the system is represented by a distorted wave and the final state is described by (i) a product of two unscreened Coulomb functions and (ii) product of a plane wave and Coulomb function.
Abstract: Positron impact ionisation cross sections for helium atoms have been calculated in the energy range 30-150 eV. The initial state of the system is represented by a distorted wave and the final state is described by (i) a product of two unscreened Coulomb functions and (ii) a product of a plane wave and the Coulomb function. The corresponding two sets of results using the plane wave in the incident channel have also been reported. The authors' results have been compared with other existing theoretical and experimental estimates of e+-He ionisation cross sections and experimental values of e--He ionisation cross sections.
31 citations
TL;DR: The first-Born-approximation results of the 2p-excited-state capture cross section in the case of helium is reported for the first time and the first Born approximation is found to be unsuitable for prediction of the rearrangement processes.
Abstract: A distorted-wave model (Phys. Rev. A 27, 1904 (1983); 28, 2180 (1983)) is applied to calculate the formation of positronium in the n = 2 states in e/sup +/ scattering from hydrogen and helium atoms. The incident wave is represented by a polarized-orbital method. The first-Born-approximation results of the 2p-excited-state capture cross section in the case of helium is reported for the first time. The first Born approximation is found to be unsuitable for prediction of the rearrangement processes. The present total (ground- and excited-state) positronium-formation cross sections have been compared with the corresponding observed values of Fornari et al. (Phys. Rev. Lett. 51, 2276 (1983)) and of Charlton et al. (J. Phys. B 16, L465 (1983)).
25 citations
TL;DR: In this paper, the synthesis, characterisation, structure, redox equilibria and reactivity of nickel(III) and nickel(IV) complexes are reviewed, and the possible significance of the present complexes in the context of the nickel-containing methanogenic enzymes is noted.
Abstract: Model complexes of nickel(III) and nickel(IV) are furnished by hexadentate and tridentate oxime-imine-amine ligands derived by the condensation of biacetyl monoxime with amines. The synthesis, characterisation, structure, redox equilibria and reactivity of these complexes are critically reviewed. Correlations and generalisations pertaining to oxidation state stability, electroprotic equilibria and reaction mechanisms are examined. The possible significance of the present complexes in the context of the nickel-containing methanogenic enzymes is noted.
23 citations
TL;DR: In this article, the thermal stability and electrical, galvonomagnetic, thermoelectric and optical properties of indium tin oxide (ITO) films were evaluated using the d.c. sputtering technique.
18 citations
TL;DR: The ligating behavior of the normally tridentate but potentially tetradentate ligand 3-hydroxyimino-2-butanone-1-benzoylhydrazone (LH2) towards CuII and NiII ions has been investigated in this paper.
Abstract: The ligating behaviour of the normally tridentate but potentially tetradentate ligand 3-hydroxyimino-2-butanone-1-benzoylhydrazone (LH2) towards CuII and NiII ions has been investigated The ligand reacts in either its keto or enol form, depending on the pH of the reaction medium Metal complexes of the type [Cu(LH2)]X2 · H2O (X = Cl, NO3 or ClO4), [Ni(LH2)2]X2 · 2H2O (X = Cl, Br, NO3 and ClO4), Cu(L) and Ni(L) have been isolated and characterised by spectral (uv-vis, ir and epr) and magnetic susceptibility measurements Location of the bonding sites and the probable structures of the complexes has also been discussed The reactions of Cu(L) and Ni(L) with pyridine have also been examined
14 citations
TL;DR: In this paper, the bulk properties of nuclear matter are studied by considering a chirally invariant lagrangian which contains an interaction term involving scalar and vector mesons, of the form (apart from a numerical factor) used by Boguta.
14 citations
TL;DR: Two complextrans-NiL2 (NCS)2] (L =N, N-dimethyl-1,3-propanediamine) synthesised from solution in two isomeric forms (1) and (2), exhibit similar colours, magnetic moments and electronic spectra, but differ in their i.r. spectra and x-ray powder diffraction patterns.
Abstract: Two complextrans-NiL2 (NCS)2] (L =N, N-dimethyl-1,3-propanediamine) synthesised from solution in two isomeric forms (1) and (2), exhibit similar colours, magnetic moments and electronic spectra, but differ in their i.r. spectra and x-ray powder diffraction patterns. We suggest they possesstrans- chair-chair andcis-chair-chair chelate conformations, respectively. Complexes (1) → (2) isomerise (temperature range 382–397.5 K; ΔH = 5.12 kJ mol−1) in the solid state. Isomer (2) is converted into isomer (1) upon recrystallisation from chloroform. Thetrans-[NiL2NCSe)2] complex does not isomerise upon heating. The compound [NiL(NCS)2], prepared by thermal decomposition of [NiL2(NCS)2], possesses octahedral polymeric structure in which the diamine is chelated and all the thiocyanato groups are bridging.
13 citations
TL;DR: In this article, the deaquation behavior of [NiL3]SO4·2 H2O appears interesting, and its monohydrate undergoes a solid-state reaction without mass loss, showing an exothermic peak at 95 °C (ΔH=− 5.1 kJ mole−1).
Abstract: Thermal studies have been carried out on [NiL3]X2·n H2O, whereL=1,2-propanediamine;X=Cl−, Br−, SCN−, 1/2SO42− and 1/2 SeO42−; andn= 2, 1.5 and 0. [Ni2L5(NCS)2](SCN)2 and [NiL2SO4] have been synthesized pyrolytically in the solid-state from their mother diamine complexes. The deaquation behaviour of [NiL3]SO4·2 H2O appears interesting, and its monohydrate undergoes a solid-state reaction (88–102°) without mass loss, showing an exothermic peak at 95 °C (ΔH=− 5.1 kJ mole−1).
TL;DR: In this paper, the synthesis, reactivities, solid state properties, and electronic and molecular structure of chromium(IV) and chromium-V compounds that have been isolated in pure form are discussed.
Abstract: This review provides information on synthesis, reactivities, solid state properties, and electronic and molecular structure of chromium(IV) and chromium(V) compounds that have been isolated in pure form. Spectroscopic properties, especially EPR of Cr5+ and Cr4+ ions doped in various host lattices, are also discussed. However, compounds that generated in solution as transient species, or occured as intermediates in redox reactions, lie outside the scope of discussion. The types of compounds which received major consideration are: oxo-compounds, peroxo complexes, halo and oxyhalo complexes, alkoxides, amides, alkyls, hydroxy carboxylates and macrocyclic compounds. Literature through 1984 is covered. It will be apparent from this article that certain aspects of chromium(IV) and chromium(V) chemistry will get enriched in future.
TL;DR: In this article, water adsorption and reaction on a clean and on an oxygen-covered Ni(111) surface is studied theoretically with a Ni10 model cluster using ASED molecular orbital theory.
TL;DR: In this paper, the antimony impurity levels have been postulated to exist between the bands L v and L c, which together with the existing band structure of Bi-Sb alloys can explain the observed behaviour of both the alloys of which one is a semimetal and the other a semiconductor.
TL;DR: In this paper, the photoisomerization of cis-benzocycloheptenone to trans benzocycloenone and its cycloaddition with selected dienes is reported for the synthesis of trans fused benzobicyclo[5.3.0]decanes 10, 12 and benzobicycleclo [5.4.4]undecanes 13, 15.
TL;DR: In this article, the authors report the first ab initio molecular applications of linear response theory in the coupled-cluster framework for calculating inner and outer valence ionization potentials (IPs).
TL;DR: In this paper, a convenient route for the synthesis of benzohydropentalene 14 and benzohydroazulenes 21 and 22 is described for entry into a number of tri-and tetracyclic terpenoids.
TL;DR: The microstructure and growth of CdTe films deposited onto glass and freshly cleaved NaCl substrates are critically studied by a TEM Fully oriented growth was observed when DTe was deposited onto NaCl at the optimum deposition conditions as mentioned in this paper.
TL;DR: In this paper, an external heavy atom induced quenching of luminescence emission of carbazole in n-hexane and methylcyclohexane in the presence of chloro-and bromoacetic acids at 300 K and 77 K was described.
TL;DR: In this paper, a stereocontrolled total synthesis of the title compound, a marine natural product as well as a degradation product of sigmosceptrellins and palauolide, has been accomplished by a simple route broadly applicable to certain trans-clerodanes and congeners.
TL;DR: The present calculated results are found to be in good agreement with the available experimental findings and the existing theoretical calculations in the high-energy region.
Abstract: A method has been derived for the evaluation of the Coulomb integral containing the product of a Coulomb wave function with a Slater-type orbital in a closed form. This method which is relevant to the charge transfer in second-order theories has been applied for the calculation of cross sections from the K shell of C, N, O, Ne, and Ar atoms by fast protons in the framework of the continuum intermediate-state approximation. The present calculated results are found to be in good agreement with the available experimental findings and the existing theoretical calculations in the high-energy region.
TL;DR: X-ray crystallographic studies on the molecular structure of α-naphthil reveal that the intercarbonyl dihedral angle is 87.29° whereas the naphthalene groups make angles of 4.26° and 6.98° with the respective carbonyl planes.
TL;DR: A detailed analysis of X-ray line broadening in filings of hexagonal zinc-silver alloys containing 09, 19 at pct (η-phase) and 131, 168, 206, 246, and 288 at e-phase have been made using Warren and Averbach's method of Fourier analysis as discussed by the authors.
Abstract: A detailed analysis of X-ray line broadening in filings of hexagonal zinc-silver alloys containing 09, 19 at pct (η-phase) and 131, 168, 206, 246, and 288 at pct Ag (e-phase) have been made using Warren and Averbach’s method of Fourier analysis The diffraction profiles from fault-unaffected [H-K = 3N] reflections 100, 002, 110, 200, 112, 004 and fault-affected [H-K = 3N ± 1] reflections 101, 102, 103, 201, 202, 203 have been chart recorded in a Geiger counter X-ray diffractometer equipped with a LiF crystal monochromator With an awareness of the small anisotropy in average domain size and strain, the deformation stacking fault probabilityα and growth fault probabilityβ have been calculated from a least-squares analysis performed on H-K = 3N ± 1 reflections It has been observed that values ofα are significantly small while values ofβ are negligible — an observation remarkably different from hexagonal alloys studied earlier The dislocation densityρ and the stacking fault energyγ have been evaluated for all the alloy compositions Since the primary slip plane may be either basal or prismatic in hcp structures, a favorable slip mode in this system has been discussed on the basis of stacking fault energy and unit cell parameters
TL;DR: In this paper, a new method based on the penalty-function way of satisfying equality constraints is proposed for the determination of constrained pure state one-electron density matrices for closed-shell many-electron systems.
Abstract: A new method based on the penalty-function way of satisfying equality constraints is proposed for the determination of constrained pure state one-electron density matrices for closed-shell many-electron systems. The algorithm suggested can handle many constraints simultaneously. Certain interesting features of the proposed algorithm are discussed with numerical examples.
TL;DR: In this article, two-photon dissociation (TPD) of HD+ was studied for the 1sσg → 2pσu transition using a direct perturbation technique, and non-resonant TPD cross sections from the ν = 6, J = 0 level of the ground 1 sσg state were calculated at different wavelengths of linearly polarised infrared photons, considering all possible bound and free intermediate states.
TL;DR: In this article, the circular dichroism spectra corresponding to 8 S 1/2 → 6 P 1/25/23/2 transitions of Gd 3+ in chiral pyrogermanate single crystal have been obtained at room temperature.
TL;DR: In this article, the corrosion products of mild steel in an acid medium are identified by Mossbauer spectroscopy using electron reemission and the diffusion coefficient which gives the rate of reaction is measured to 0.14 × 10−12 cm2/s.
Abstract: The corrosion products of mild steel in an acid medium are identified by Mossbauer spectroscopy. Using electron reemission Mossbauer spectroscopy the diffusion coefficient which gives the rate of reaction is measured to 0.14 × 10−12 cm2/s. The retardation of corrosion by an inhibitor and a surfactant is also discussed.
Die Korrosionsprodukte von weichem Stahl in saurer Umgebung werden mittels Mosbauer-spektroskopie identifiziert. Der Diffusionskoeffizient, der die Reaktionsgeschwindigkeit ergibt, wird mit der Elektronreemissions-Mosbauerspektroskopie gemessen, und betragt 0,14 × 10−12 cm2/s. Die Verzogerung der Korrosion durch einen Inhibitor und einen Surfaktant wird ebenfalls diskutiert.
TL;DR: In this paper, the structural properties of tin doped indium oxide (ITO) films have been studied by X-ray diffraction and electron microscopy using a planar magnetron configuration.
Abstract: The structural characteristics of transparent and conducting thin films of tin doped indium oxide (ITO) have been studied by X-ray diffraction and electron microscopy. The ITO films have been prepared by radio frequency sputtering employing a planar magnetron configuration. The effects of variation of substrate temperature and annealing have been studied. Films deposited at substrate temperatures up to 230° C show a marked 〈1 1 0〉 preferred orientation, whereas those deposited at 330° C are preferentially oriented in the 〈3 1 1〉 direction. Transmission electron micrographs of ITO films deposited on KCI crystals show the possible effects of strain on the structure, which are minimized to a great extent by annealing.
TL;DR: In this article, the thermal stability of the hydrated and anhydrous compounds of pyridine-2-carboxylic acid (picolinic acid) has been studied by simultaneous TG, DTA and DTG traces.
Abstract: The solid-state dehydration of the hydrated Ca(II), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) salts of pyridine-2-carboxylic acid (picolinic acid) and subsequent decarboxylation of the corresponding anhydrous salts have been studied by simultaneous TG, DTA and DTG. The sequences of thermal stability of the hydrated and the anhydrous compounds have been established from analysis of the TG, DTA and DTG traces for dehydration of the hydrated salts and for decarboxylation of the anhydrous compounds. Thermal parameters such as activation energy, enthalpy change and order of reaction for the different stages of each process have been computed by standard methods. An attempt has been made to account for the observed trend in the thermal stability of the anhydrous salts towards decarboxylation. A mechanism of thermal decraboxylation of calcium picolinate has been proposed.
TL;DR: In this article, the efficacy of a new acid-catalyzed intramolecular C-alkylation has been demonstrated by the synthesis of 1-methyl-4- p -methoxyphenylbicyclo [2.2] from easily accessible starting materials.