Rajesh Jain

Compton profile study of bonding in BeO

The isotropic Compton profile of BeO has been measured using a γ-ray Compton spectrometer which employs a 5 Ci annular 241Am source. The measurement is compared with the theoretical HF-LCAO Compton profile published by Lichanot et al. The measurement has also been compared with our calculations based on the RFA model employing different ionic wavefunctions. It is seen that the experimental Compton profile is in very good agreement with the HF-LCAO calculations. To determine the nature of bonding, equal-valence-electron-density Compton profile of BeO has been compared with that of the isovalent compound MgO. It is observed that the bonding in BeO is partially covalent and less ionic than MgO in agreement with the conclusions of the HF-LCAO calculation.

Electronic Structure of Platinum: A Compton Profile Analysis

In this paper we report the results of a Compton profile study on polycrystalline platinum. The measurement has been made using 241 Am γ-rays and is compared with APW calculations of Papanicolaou et al. and also with our calculations based on the renormalized-free-atom (RFA) model. It is seen that the incorporation of electron correlation effects improves slightly the agreement between APW theory and experiment but the best fit to our experimental data is seen for the simple RFA model for 5d 9.2 6S 0.8 configuration. A comparison of the equal valence-electron-density Compton profiles of platinum and the other two isogroup metals, namely palladium and nickel, reveals an interesting trend for the d-band width in agTeement with the results based on photoemission measurements. The d-band occupancy as determined from RFA analysis is in agreement with Lytles estimates.

High resolution Compton scattering study of molybdenum

Abstract In this paper directional Compton profiles of Mo are presented and the results compared with LCGO and APW model calculations. Both electronic structure models describe qualitatively the anisotropy of the electron momentum distribution, which is influenced by the Fermi surface topology. However, the absolute profiles indicate that electron–electron correlation effects are inadequately described within the local density approximation.

Dual frequency rectangular patch antenna with a rectangular notch for improved bandwidth performance

The simulation results of rectangular patch antenna with a rectangular notch with and without air gap are reported in this paper. The structure has three layered structure in between conducting patch and the ground plane. It is found that rectangular antenna having an appropriate size of rectangular notch resonates at two different frequencies and also provides much improved bandwidth. On the introduction of an air gap of 1.5 mm between the dielectric layers, this antenna resonates only at a single frequency but with further improved bandwidth. Improved gain, efficiency and directivity of antenna may be obtained under this condition.

Simulation of a dual band circular patch antenna with an off centered narrow ring slit

This paper presents the simulation results obtained with a circular patch antenna having an off centered narrow ring slit. With a particular location of ring slit near periphery of circular geometry, antenna resonates at two different frequencies which lie in the lower and upper band of Wi-Max communication adopted by IEEE 802.16. The efficiency and gain of antenna at one of these frequencies are better than those at other frequency while directivity is more or less same at two resonance frequencies. Experimental work is underway to test these simulation results.