Showing papers by "Indian Association for the Cultivation of Science published in 1984"
TL;DR: In this paper, the effect of a magnetic field on pyrene-N,N-dimethylaniline exciplex luminescence in methanol has been studied using an improved phase-sensitive detection technique.
47 citations
TL;DR: In this article, an open-shell many-body perturbation theory (mbpt) that applies to an incomplete model space is presented. But the effective Hamiltonian generated in the theory is hermitian.
Abstract: In this paper we have formulated an open-shell many-body perturbation theory (mbpt) that applies to an incomplete model space. The effective HamiltonianH
eff generated in our theory is hermitian. We follow the resolvent-operator based time-dependent formulation ofmbpt of Banerjeeet al, and show quite generally that, by classifying the various determinants spanning the Hilbert space as model valence spaceP, virtual valence spaceR and virtual spaceQ, a diagrammaticmbpt satisfying size consistency can be developed. The chief new features of the theory are (i) manifest hermiticity ofH
eff; (ii) presence of disconnected diagrams no part of which is a legitimate diagram (irreducible disconnected diagrams); (iii) presence of folded diagrams with components that may be irreducible disconnected diagrams; (iv) a consistent treatment of the variousn-valence sectors of the Hilbert space that may be interacting throughH
eft if valence-holes are present—in particular a modified treatment of the core-valence separation. The generalisation afforded by the theory offers useful conceptual as well as computational advantages because the convergence difficulty encountered in a complete valence space formulation may be bypassed here by keeping the offending valence space determinants out of the model space. A brief critique of the developmentvis-a-vis the only other general model space development leading to a nonhermitianH
eff is also given.
34 citations
TL;DR: In this article, the type integral Rinfinity r-nF1(r)F2(r), where F1 and F2 are Coulomb functions, is used for various problems in atomic physics.
Abstract: Integrals of the type integral Rinfinity r-nF1(r)F2(r) dr, where F1 and F2 are Coulomb functions, are required for various problems in atomic physics Methods are described for the evaluation of such integrals; they involve deformation of the integration contours into the complex plane
30 citations
TL;DR: In this paper, a detailed analysis of the x-ray diffraction line profiles of binary fcc Ag-and Cu-base alloys has been carried out using the Warren-Averbach method of peak-shift and peak-asymmetry.
Abstract: This review concerns our recent investigations with a series of binary fcc Ag- and Cu-base alloys (viz Ag-Ga, Ag-Ge, Ag-Al and Cu-Ga, Cu-Ge) from detailed analyses of x-ray diffraction line profiles, the importance of which has been briefly summarized. The theoretical formulations of the Warren-Averbach’s method of Fourier analysis of peak-shapes along with the methods of peak-shift and peak-asymmetry have been outlined. A preview on the significant studies carried out earlier with Ag- and Cu-base (fcc) binary alloys has been made in short. A detailed analyses on the recorded profiles in the present considerations revealed, in general, quantitative estimates of several microstructural parameters characterising the deformed state of the materials namely, propensity of stacking faults (intrinsic, extrinsic and twin faults), rms microstrains, coherent domain sizes, long-range residual stresses, lattice parameter changes, dislocation density and stacking fault energy. The results indicate a general trend of increase in the concentrations of stacking faults, primarily, of intrinsic character, with increase in solute concentrations; which are solely responsible for the observed peak-shifts as well as domain size broadening. Small asymmetry in the profiles is due to the presence of extrinsic stacking faults, relatively less in magnitude compared to the intrinsic ones while the deformation twin faults are almost absent—an observation with significance. The dislocation density, quite appreciable in magnitude, has been evaluated from the anisotropic values of the coherent domain sizes and rms microstrains. The stacking fault energies of pure Ag and Cu, an important parameter have also been estimated and compared with those obtained from electron microscopy. Annealing experiments with a Ag-5·8% Al alloy, aluminium being a precipitating solute, do not reveal any detectable evidence of solute segregation at the stacking faults. The occurrence of stacking faults in the alloy systems has been correlated with a number of physical factors involving solvent-solute types.
28 citations
TL;DR: In this paper, a generalised method for the calculations of inelastic collision strengths for scattering of electrons by ions in dense plasma taking account of the shielding of the Coulomb potential by the Debye-Huckel model is presented.
Abstract: The authors present a generalised method for the calculations of inelastic collision strengths for scattering of electrons by ions in dense plasma taking account of the shielding of the Coulomb potential by the Debye-Huckel model. Matrix elements between arbitrary initial and final Slater orbitals are obtained in closed form. Results for the 1s-2p transition in the He+ ion due to Hatton et al. (1981) have been reproduced and new results have been presented for 1s-3d and 1s-4f transitions.
28 citations
TL;DR: Developpement d'une telle fonctionnelle energie en utilisant une forme specifique de la representation de la Fonction d'onde par un developpements d'amas as mentioned in this paper.
Abstract: Developpement d'une telle fonctionnelle energie en utilisant une forme specifique de la representation de la fonction d'onde par un developpement d'amas
26 citations
TL;DR: In this paper, the transition energies and excited state wavefunctions of Li, Be+, B2+ and C3+ for the transitions were estimated from the position of the poles of a linearised variational functional.
Abstract: Time-dependent HF (RPA) calculations have been performed to estimate the transition energies and excited state wavefunctions of Li, Be+, B2+ and C3+ for the transitions 1s
22s∶ 2
S → 1s
2
ns ∶ 2
S (n = 3,4, 8) The excitation energies and excited state wavefunctions are extracted from the position of the poles of a linearised variational functional The excitation energies are in excellent agreement with those obtained spectroscopically The excited state wavefunctions are utilised to find the matrix elements of different operators and the cusp values
19 citations
TL;DR: The chelating behavior of a new multidentate ligand with tuberculostatic activity toward Cu( II) and Ni(II) ions has been studied and it is found to chelate the above metal ions in both its keto and enol forms.
19 citations
TL;DR: In this article, the crystal structure of the nickel(II) complex (C20H22N6S2Ni) of the N2S2 ligand hexan-2,5-dionebis(4-phenyl-thiosemicarbazone) has been solved using diffractometric data.
19 citations
TL;DR: The 2 K 15/2 and 2 K 13/2 states of Er 3+ have been assigned on the basis of the circulardichroism/optical density (CD/OD) ratio in two optically active crystals, Er-pyrogermanate and Er-diglycollate as discussed by the authors.
18 citations
TL;DR: In this paper, Cadmium sulphide films were deposited by hot wall technique at a system pressure of ≈10−6 Torr onto corning 7059 glass slides.
TL;DR: In this paper, the electronic and optical properties of p-type a-Si:H films prepared by the rf glow discharge decomposition of a mixture of silane and diborane gases have been studied.
TL;DR: In this paper, a joint theoretical-experimental study of the Thomas peak in electron capture by several-MeV protons on hydrogen and on He is presented, and the folding of theoretical cross sections with the experimental angular resolution, required to compare theory to experiment, is explained and illustrated.
Abstract: A joint theoretical-experimental study of the Thomas peak in electron capture by several-MeV protons on hydrogen and on He is presented. The folding of theoretical cross sections with the experimental angular resolution, required to compare theory to experiment, is explained and illustrated. Strong-potential Born calculations, with and without the full peaking approximation, are presented and compared to observation. Also compared are recent continuum-distorted-wave calculations of Salin and Rivarola.
TL;DR: In this paper, the donor sites ONNS of the cobalt(III) complexes [CoL1-(H2O)2]X (X=Cl or ClO4) appear to be betrans-diaqua-species.
Abstract: Complexes of nickel(II), palladium(II), copper(II), cobalt(II), and cobalt(III) with methyl-2-(β-salicylaldiminoethyl)-cyclopent-1-en-dithiocarboxylate (H2L1) and methyl-2-(β-salicylaldiminoisopropyl)cyclopent-1-en-dithiocarboxylate (H2L2) have been prepared. They contain the donor sites ONNS. The metal(II) ions from neutral, monomeric square planar chelate complexes. The cobalt(III) complexes [CoL1-(H2O)2]X (X=Cl or ClO4) appear to betrans-diaqua-species. All compounds have been characterized by a number of physico-chemical methods.
TL;DR: In this paper, undoped and p-type hydrogenated amorphous silicon carbide (a Si C:H) films were studied under different deposition conditions by the r.f. glow discharge decomposition of gas mixtures of silane and methane.
TL;DR: The effects of variation in the concentration of H2 in the mixture were also investigated in this paper, showing that the activation energy increases slowly with H2 concentration up to 25% and then decreases with a further increase in the H 2 concentration.
TL;DR: In this article, the influence of various deposition parameters on the properties of amorphous silicon thin films produced by r.f. magnetron sputtering was studied and the results show that the magnetron-based sputtering method has good potential for producing high quality a-Si films.
TL;DR: In this paper, the spin-orbit coupling arising from the non-planarity of the lone-pair orbital of the oxygen atom in diphenyl ether was found to contribute to the increase in the phosphorescence.
TL;DR: Pyridine has been found to exhibit weak but readily observable dual fluorescence (S 2 (ππ ∗ )→ S 0 - major, S 1 (nπ ∆ )→S o - minor) as well as dual phosphorescence (T 1 (π π ∆ → S o fluorescence) in its pure crystalline state and in a variety of rigid matrices at 77 K as discussed by the authors.
TL;DR: A model-potential method is used to investigate elastic e/sup + -/-Ar scattering at low incident energy, up to 18 eV, and results are found to be in good agreement with the existing theoretical predictions and measured values.
Abstract: A model-potential method due to Khan et al. (Phys. Rev. A 29, 3129 (1984)) is used to investigate elastic e/sup + -/-Ar scattering at low incident energy, up to 18 eV. The effect of short-range correlation has been included via an adjustable parameter. Same polarization potentials have been used for both the electron and positron cases, and scattering parameters are presented. The results are found to be in good agreement with the existing theoretical predictions and measured values.
TL;DR: In this article, an antiferromagnetic model with N-eel states as ground states was discussed and the Finite-temperature properties of this model were compared with those of the isotropic Heisenberg Hamiltonian through a similar method.
Abstract: We discuss in one as well as three dimensions an antiferromagnetic model with N\'eel states as ground states. Long-range order exists for this Hamiltonian. Finite-temperature properties of this Hamiltonian can be computed through the usual Green-function method and the results obtained are identical with those of the isotropic Heisenberg Hamiltonian through a similar method. The reason for this identity and its implication in analysis of experimental data are discussed.
TL;DR: The capsular polysaccharide from Streptococcus pneumoniae Type 23 (S-23) was found to contain D-galactose, D-glucose, L-rhamnose, glycerol, and phosphorus in the ratios of 1:1:2:0.6:1.
TL;DR: Differential scanning calorimetric measurements have been carried out for Cul, CuBr, Agl, Ag2S, NaNO2, NaNo3 and KSCN as discussed by the authors.
Abstract: Differential scanning calorimetric measurements have been carried out for Cul, CuBr, Agl, Ag2S, NaNO2, NaNO3 and KSCN. First-order phase transformations occur with the compounds Cul, CuBr, Agl and Ag2S; NaNO2, NaNO3 and KSCN exhibit λ-type transformations. The enthalpy changes due to phase transitions have been determined. Thermal hysteresis exhibited by these compounds have been examined in the light of their change in unit cell volumes.
TL;DR: In this paper, a degraded polysaccharide was prepared by autohydrolysis of an aqueous solution of PS-AII, which yielded d-galactose, d-glucose, l -arabinose, and d -glucuronic acid in the mole ratios of 3.9:2.
TL;DR: In this article, the composition of the cobalt-II and copper-II complexes is [M(H2L3)X2] (X=Cl or Br) which contain the chromophore [MN3X2].
Abstract: Nickel(II), palladium(II), cobalt(II) and copper(II) complexes of the ligandN,N′-1,2-propane-bis(methyl 2-amino-cyclopent-1-ene-dithiocarboxylate) (H2L1),N,N′-1,3-propane-bis(methyl 2-aminocyclopent-1-ene-dithiocarboxylate) (H2L2) andN,N′-[bis(methyl 2-aminocyclopent-1-ene-dithiocarboxylate)] diethylenetriamine (H2L3) have been synthesised. Both H2L1 and H2L2 form complexes of the type ML, and all but the copper(II) complexes, are square planar. In the copper(II) complexes tetrahedral distortion is significantly more with CuL2. From H2L3 square planar complexes of the type [M(HL3)X] (M=Ni, X=Cl, Br, I or SCN; M=Pd, X=Cl or Br) have been obtained in which the donor unit involved is N2SX. The composition of the cobalt(II) and copper(II) complexes is [M(H2L3)X2] (X=Cl or Br) which contain the chromophore [MN3X2].
TL;DR: In this paper, the authors used a Shimadzu thermal analyzer to investigate the thermal properties of bis-and tris-diamine complexes and 1,3-Diaminopropane complexes.
TL;DR: In this paper, a crystal field analysis of the experimental results on the magnetic susceptibilities and their anisotropies in Ho(OH)3 and Tb(OH)-3 was made with a view to resolve the previous anomalies observed in the results of specific heat studies.
TL;DR: In this paper, a time-dependent perturbation theory is presented in a form that naturally eliminates the undesirable "secular " terms for a timeindependent perturbations, permits an order-by-order calculation of the exact wavefunction for a ‘resonant’ harmonic perturbing and offers a simple route to establish the adiabatic hypothesis in quantum mechanics.
Abstract: Within the framework of the method of variation of constants, time-dependent perturbation theory is presented in a form that naturally eliminates the undesirable ‘secular ’ terms for a time-independent perturbation, permits an order-by-order calculation of the exact wavefunction for a ‘resonant’ harmonic perturbation and offers a simple route to establish the adiabatic hypothesis in quantum mechanics. The formulation rests on the introduction of a flexibility in the choice of the phase factors associated with the varying amplitudes, together with development of a perturbation procedure that closely resembles the Brillouin-Wigner formalism in the static case, and which exploits the flexibility of the phase factors at each order of the theory.
TL;DR: In this paper, the continuous oscillator strength and photoionization cross section of He and Li/sup +/ were calculated by using polarized-orbital method and matrix elements involving distorted-target wave functions have been included.
Abstract: The continuous oscillator strengths and photoionization cross section of He and Li/sup +/ are calculated by using polarized-orbital method. Matrix elements involving distorted-target wave functions have been included. The results are found to be in excellent agreement with the experimental values.
TL;DR: In this paper, a model calculation of the optical activity has been performed to correlate the observed rotational strengths for crystal-field component-to-component transitions for cubic potassium praseodymium double nitrate (anhydrous), K 3 Pr 2 (NO 3 ) 9.