Arun Kumar Chatterjee

The electronic structure and chemical bonding mechanism of silver oxide

The electronic structure and the chemical bonding mechanism of silver oxide are studied on the basis of band-structure calculations, using the full-potential linearized augmented-plane-wave (FLAPW) method. Our calculations indicate that silver oxide is a metal (or a semi-metal). Total and partial densities of states and electron densities were calculated and are utilized to give an interpretation of the chemical bonding. The admixture of the Ag 5s states with the Ag 4d-O 2p bands proved to be essential for the covalent bonding effect, since pure 4d-2p bands, with bonding and antibonding states fully occupied, do not lead to a covalent energy gain. It is found that there are significant deviations from a simple ionic picture due to the depletion of the valence band of the Ag 4d electrons, leading to non-spherical charge density around the silver.

Compton scattering studies of the electron momentum distribution in indium phosphide

Abstract The electron momentum anisotropy of indium phosphide has been studied by measuring the directional Compton profiles of indium phosphide single crystals with the use of radiation from an 241 Am gamma source. Three different samples, cut along the [100], [110] and [111] planes, were used. The experimental anisotropy has been compared with the results based on the linear combination of Gaussian orbitals (LCGO) method. The agreement is very good with our theoretical results. It is found that the extrema appearing in the dependences on q of the anisotropies have an intimate connection with the bonding properties of the semiconductor. A self-consistent, all-electron, local density calculation for the partial density of states, total density of states and the charge analysis is also presented here.

Compton profile of scandium oxide

Abstract In this paper we report the measurement of the Compton profile of polycrystalline scandium oxide using 59.54 keV gamma radiation from a Am 241 source. The experimental results are compared with the theoretical Compton profile values calculated based on the linear combination of Gaussian orbital (LCGO) method. The theoretical values from such calculations agree well with the experimental results.

Compton scattering study on the electronic properties of niobium carbide and niobium nitride

Abstract The electronic structure, experimental Compton profile and the chemical bonding mechanism of niobium carbide and niobium nitride are studied on the basis of the band structure calculations, using a self-consistent, all-electron, linear combination of Gaussian orbitals (LCGO) calculation based on density functional theory. Isotropic Compton profiles of niobium carbide have been measured, using a conventional technique based on 59.54 keV gamma-radiation with a solid state detector. The agreement between the experimental and the theoretical momentum density is very good. It is shown that the anisotropies at low momentum are heavily influenced by the particular shape of the Fermi surface. The charge distributions resulting from valence bands in different regions of the unit cell are discussed. The limitations of the rigid band structure model are illustrated and general trends in the chemical bonding are discussed.

Compton profile of cuprous oxide by linear combination of Gaussian orbitals

In this paper we report self-consistent all-electron local-density calculations using the linear combination of Gaussian orbitals method for cuprous oxide. We calculated the directional Compton profile and their anisotropic effect. The spherical average Compton profile has also been calculated and compared with the experimental results. We also calculated the density of states of cuprous oxide.

Compton profile of cuprous oxide

Abstract In this paper we report measurements of the Compton profile of polycrystalline cuprous oxide using 59.54 keV γ-radiation. Our measured data are compared with our calculated results based on the Renormalized Free Atom model and using Watsons + 1 well solution for the O 2p state with different Cu 3d-4s and O 2p configurations. A Cu 3d-4s hybridization in Cu 2 O is found, and best agreement with experiment is obtained for a Cu 3d 9.8 4s 0.2 O 2p 6 configuration.

MEASUREMENT OF ELASTIC NEUTRONS BY ORGANIC SCINTILLATORS.

Abstract A method for the measurement of elastically scattered neutrons in the presence of inelastic ones has been developed. The method consists in measuring the neutron intensity at two different biases of the recoil proton scintillation neutron counter. It has been shown that these experimental results are sufficient to determine the elastic neutron intensity unambigously. No additional data like differential elastic neutron cross sections etc. are required in this method. The experimental test of this new procedure has been carried out by measuring nonelastic cross sections of nuclei for 14.8 MeV neutrons. The experimental results indicate the consistency and the validity of the method.

Measurement of absolute efficiency of solid state track detectors for 14 MeV neutrons

Abstract Efficiencies of solid state track detectors were measured with 14 MeV neutrons. Detectors were etched by following the conventional method of etching. Tracks were counted by a scanning electron microscope.

On the non-elastic cross section of 14.2 MeV neutrons

Abstract Non-elastic scattering cross sections for 14.2 MeV neutrons have been measured for the elements O, Al, Cu, Cd, Sn, W and Pb employing the modified sphere transmission technique. Essentially it involves the simultaneous measurement of neutron transmission at different bias levels of the detector providing scope for better experimental accuracy. An automatic search routine was used to calculate an optical model fit to the data. An average set of parameters was obtained by analysing non-elastic as well as differential elastic cross-section data together.

Investigations on the improvement of the effective resolution in scintillation spectrometers

Abstract A method for resolving peaks in a scintillation spectrum which otherwise would overlap due to photomultiplier statistics is presented here. The arrangement is quite flexible for varying light divisions between the two photomultipliers viewing one scintillating crystal. A differential discriminator accepts pulses from a fixed portion of the spectrum from one of the tubes whereas another differential discriminator scans the spectrum from the second tube, coincidence gated by the first. Experimental results presented here show that the 1.33 MeV monoenergetic line from 60Co source was separated and resolved; the effective resolution was made better by increasing the light input to the second photomultiplier.