Indian Journal of Pure and Applied Physics

 

Total visitors:1,429 since 20-6-05

 ISSN: 0019-5596

CODEN: IJOPAU 43 (6) 395-474

VOLUME  43

NUMBER 6

JUNE 2005

 

CONTENTS

 

Review Article

 

Adaptive optics and its applications

D Mohan, S K Mishra & S K Saha*

399

General

 

Convective flow of two immiscible viscous fluids using Brinkman model

Atul Kumar Singh

415

The Physics of Elementary Particles and Fields

 

Energy values for light quark system in the ultra-relativistic limit

U Laha

469

Nuclear Physics

 

Gamma activity in some environmental samples in south Egypt

A M El-Arabi

422

Atomic and Molecular Physics

 

 

Potential function for diatomic molecules

S V Birajdar, C J Kadam, R M Shelke & S H Behere*

427

Condensed Matter: Structural, Mechanical and Thermal Properties

       

Theory of multilayer solar cells

K M Khanna*, R Ekai, C K Ronno, S K Rotich & P K Torongey

432

Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties

 

Computational interfacing of resistivity of high temperature superconductor using Visual Basic program

Intikhab A Ansari*, K P Singh, M Shahabuddin, M Husain & A Gupta


439

Study of dielectric properties of a-alumina doped with MnO, CdO and MnO

I S Ahmed Farag, I K Battisha* & M M El-Rafaay

446

Spectroscopic and thermodynamic analysis of enolic form of 3-oxo-l-gulofuranolactone

S Srinivasan, S Gunasekaran*, U Ponnambalam, A Savarianandam,

S Gnanaprakasam & S Natarajan

459

Effect of metallic substitution on the optical, mechanical and photoconducting properties of

L-arginium diphosphate single crystals

A Joseph Arul Pragasam*, S Selvakumar, J Madhavan, D Prem Anand & P Sagayaraj

463

________

*The corresponding author has been indicated by (*) mark in case of papers with more than one author

 


Indian Journal of Pure & Applied Physics

Vol. 43, June 2005, pp. 399-414

 

 

Adaptive optics and its applications

D Mohan, S K Mishra & S K Saha*

Instruments Research & Development Establishment, Dehra Dun, India

*Indian Institute of Astrophysics, Bangalore, India

[E-mail: sks@iiap.res.in]

Received 4 March 2005; accepted 1 April 2005

The adaptive optics (AO) system combines technologies that enable corrections in real time for the deleterious effects of the atmosphere allowing terrestrial telescopes to achieve their near diffraction-limit. Such a system introduces controllable counter wavefront distortions, which both spatially and temporally follow that of the atmosphere. AO system has advantages over post-detection image restoration techniques that are limited by noise and recovers near diffraction-limited images and improves the point source sensitivity. This system may become standard tool for the new generation large optical imaging systems. Development of such a technique was made possible due to the significant improvements in technological innovation over the past few decades. After a brief introduction on the deleterious effects of the atmosphere on the image, this article discusses in detail about required components in order to develop the AO system and its applications in various fields, particularly in observational astronomy.

Keywords: Adaptive optics, Wavefront sensor, Deformable and Tip-tilt mirrors, Telescope, Turbulence

IPC Code: G01M11/00

 

Indian Journal of Pure & Applied Physics 

Vol. 43, June 2005, pp. 415-421

 

 

Convective flow of two immiscible viscous fluids using Brinkman  model

Atul  Kumar  Singh

Department of Mathematics, V S S D College, Kanpur 208 002

Received 30 July 2004; revised 1 February 2005; accepted 12 April 2005

Generalised Couette flow of two viscous, incompressible, immiscible fluids with heat transfer through two straight parallel horizontal walls is studied. A naturally permeable material of high porosity bound below the lower wall and the flow inside the porous medium is assumed to be of moderate permeability, modeled by Brinkman equation. Analytical solutions of the momentum and energy equations have been obtained for the flow domain by dividing it into three zones. Appropriate matching conditions of velocity and temperature have been used to link various flow regimes. The effects of inverse permeability parameter, Reynolds number and viscous parameter on velocity fields and temperature fields in various zones along with mass flow rate, skin-friction at the walls and rates of heat transfer have been presented.

Keywords: Convective flow, Heat transfer, Porous medium

IPC Code: G01N

 

Indian Journal of Pure & Applied Physics 

Vol. 43, June 2005, pp. 422-426

 

 

 

gamma activity in some environmental samples in south egypt

 

A M El-Arabi

Physics Department, Faculty of Science Qena, South Valley University, Egypt

E-mail elarabi21@yahoo.com

Received 29 September 2004; revised 27 December 2004; accepted 20 January 2005

As a part of national survey to evaluate natural radioactivity in the environment, concentration levels of natural radioactivity have been analyzed from more than 108 environmental samples taken from wadi Allaqi area, south Egypt. The distribution of naturally occurring radionuclides of 226Ra, 232Th and 40K in the samples (soil, granite, grass and water) have been measured using a high purity germanium detector. The specific activities in these samples, having a radium equivalent activity of less than 370 Bq.kg-1, when evaluated for radiological effects show that all samples meet the external gamma-ray dose limitation of 1.5 mSv.y-1. The data presented here will serve as a baseline survey for primordial radionuclide concentrations in igneous and sediment of the area.

Keywords: Radionuclides, Radioactivity, Dose rate

IPC Code: G01T

Indian Journal of Pure & Applied Physics 

Vol. 43, June 2005, pp. 427-431

 

 

Potential function for diatomic molecules

 

S V Birajdar1, C J Kadam2, R M Shelke3 & S H Behere4

1Department of Physics, S B College of Science, Aurangabad 431 001

2Department of Physics, Maharashtra Mahavidyalaya, Nilanga, Dist Latur 431 521

3Shri Chhatrapati Shivaji Mahavidyalaya, Shrigonda, Dist Ahmednagar 413 701

4Department of Physics, Dr Babasaheb Ambedkar Marathwada University, Aurangabad 431 004

(E-mail: subhashbehere@yahoo.com)

Received 24 February 2004; revised 11 April 2005; accepted 19 April 2005

The potential energy function suggested by Rafi (Indian J Phys, 74B (485) 2000) has been investigated further and the adjustable parameter c appearing in the potential function has been calculated. Using Varshni’s formulation, the value of c has been calculated for fifty randomly selected diatomic molecules. Besides the individual value of c, an average value of c has also been used to calculate the potential energy curves for the ground states of CO and I2 molecules using this potential. These potential energy curves are compared with RKR and Morse curves.

Keywords: Potential energy curves, Potential energy function, Diatomic molecules

 

Indian Journal of Pure & Applied Physics 

Vol. 43, June 2005, pp. 432-438

 

 

 

 

Theory of multilayer solar cells

 

K M Khanna, R Ekai, C K Ronno, S K Rotich & P K Torongey

Moi University, Physics Department, P O Box 1125, Eldoret, Kenya

Received 15 September 2004; revised 25 January 2005; accepted 18 April 2005

An expression has been derived for the absorption coefficient a of an incident radiation with energy ħw by a semiconductor with band-gap DE0. For a multilayer solar cell composed of seven layers that facilitate the solar cell to use the seven colours of the white light for maximum efficiency, the expression for the solar current ISC has been used to calculate the value of the charge carrier density n in each layer. ISC should be the same through all the layers for the layers to be connected in optical series. For such an arrangement, the efficiency of the multilayer solar cell turns out to be more than 42%.

Keywords: Multilayer solar cell, Solar current, Charge carrier density

IPC Code: F24J2/00

Indian Journal of Pure & Applied Physics 

Vol. 43, June 2005, pp. 439-445

 

Computational interfacing of resistivity of high temperature superconductor

using Visual Basic program

 

Intikhab A Ansari, K P Singh, M Shahabuddin, M Husain & A Gupta§

Low Temperature Laboratory, Department of Physics, Jamia Millia Islamia (Central University), Jamia Nagar, New Delhi 110 025

§Superconductivity and Cryogenics Division, National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110 012

E-mail: intikhab@jamia-physics.net

Received 13 January 2005; accepted 28 March 2005

The developed Visual Basic interfacing program measured the transition temperature of any high temperature superconductor by using the IEEE 488.2 GPIB card. This interfacing program is also applicable for the doped superconductors. A summary of our work on the MgB2 system is reported here.

Keywords: Resistivity, High temperature superconductor, Transition temperature

IPC Code: C04B101:00

Indian Journal of Pure & Applied Physics

Vol. 43, June 2005, pp. 446-458

 

 

Study of dielectric properties of a-alumina doped with MnO, CdO and MoO

 

I S Ahmed Farag, I K Battisha & M M El-Rafaay

National Research Center Solid State Department, Dokki, Cairo, Egypt

Received 27 April 2004; revised 13 September 2004; accepted 19 October 2004

The dielectric constant (e),conductivity (s) and activation energy (Eg) of a-alumina doped with different molar ratios ranging from 0.01 to 0.19 of manganese oxide (MnO), and from 0.01 to 0.16 for both molybdenum oxide (MoO) and cadmium oxide (CdO) were studied. The XRD patterns reveal clearly that the prepared samples, consist of only single phase (a-alumina phase). The crystallite size and micro-strain of the investigated samples were calculated. The crystallite size increases with increasing dopant concentration. But the rate of the crystallite growth differs from one system to another. The value of  e has been measured in a frequency range 42 Hz-5 MHz as a function of temperature ranging from 100 to 450°C. The possible explanations and the role of some impurities (mainly Mn, Mo and Cd) are analyzed. The value e of pure sample increases from 9.4 to 10.63 as a function of temperature at constant frequency 1 MHz. In this material, the value of e increases with increase of temperature due to space charge polarization and crystal defects, while it decreases as a function of frequency due to the scattering of charge carriers at high frequencies. From the plots of log s as a function of the reciprocal of temperature at different frequencies, it has been shown that more than one straight line with different shapes are obtained, indicating different conduction mechanisms at 100 kHz and 1 MHz. An increase in the conductivity with increasing dopant concentration appeared and it could be related to the increase of the charge carriers, which are localized at ions or vacant sites. The activation energies for conduction in the high temperature region are calculated and found to be equal to 0.489, 0.457 and 0.459 eV for 0.01% of Mn, Mo and Cd, cations respectively at constant frequency of 100 kHz. The lower activation energy values for conduction in doped materials may be attributed to a larger charge carrier concentration in them compared to pure a-alumina. The XRD was elucidating to confirm that the obtained phase is a single a-alumina phase.

Keywords: Dielectric constant, Conductivity, Alumina, Micro-starin, Crystallite

IPC Code: G01R27/26

Indian Journal of Pure & Applied Physics

Vol. 43, June 2005, pp. 459-462

 

Spectroscopic and thermodynamic analysis of enolic form of
3-oxo-L-gulofuranolactone

S Srinivasan+, S Gunasekaran*, U Ponnambalam+, A Savarianandama, S Gnanaprakasama & S Natarajanb

+Department of Physics, Presidency College, Chennai, India

*Department of Physics, Pachaiyappa’s College, Chennai, India

aDepartment of Physics, St.Joseph’s College, Trichy, India

bDepartment of Physics, Kongunadu College, Coimbatore, India

Received 15 June 2004; revised 15 March 2005; accepted 20 April 2005

A qualitative analysis of the enolic form of 3-oxo-L-gulofuranolactone (ascorbic acid) has been made by a satisfactory vibrational band assignment using FTIR and FT Raman spectra. The calculated theoretical vibrational frequencies are compared with the experimental frequencies by employing the molecular mechanics method using MM3 force field. The observed frequencies are used to compute the thermodynamic functions, namely, the entropy, heat capacity and heats of formation using standard expressions, at one atmospheric pressure in the 298-398 K temperature range.

Keywords: FTIR, FT Raman spectra, Molecular mechanics, Vibrational band assignment, Thermodynamic functions

IPC Code: G01J 3/28

Indian Journal of Pure & Applied Physics

Vol. 43, June 2005, pp. 463-468

 

Effect of metallic substitution on the optical, mechanical and photoconducting properties of L-arginium diphosphate single crystals

 

A Joseph Arul Pragasam*, S Selvakumar, J Madhavan, D Prem Anand & P Sagayaraj

*Department of Physics, Sathyabama Institute of Science and Technology, Deemed University, Chennai 600 119

Department of Physics, Loyola College, Chennai 600 034

Received 9 December 2004; revised 7 February 2005; accepted 16 March 2005

L-arginium diphosphate (LADP) is one of the important analogs of LAP crystal. LADP has excellent optical, thermal and mechanical properties, which make it a potential candidate for photonics device fabrication. The present work deals with the growth and characterization of metal (Cu2+ and Mg2+) substituted single crystals of LADP. The grown crystals are subjected to single crystal XRD, AAS, FTIR, DRS spectra and microhardness studies. Microhardness studies indicate that the presence of dopant has enhanced the hardness of the material. The photoconductivity study reveals the positive photoconducting nature of both pure and doped crystals.

Keywords: Non-linear optical properties, Vicker’s hardness number, Metal substitution, Photoconductivity

IPC Code: H01L21/00

Indian Journal of Pure & Applied Physics 

Vol. 43, June 2005, pp. 469-470

 

 

 

Note

 

 

Energy values for light quark system in the ultra-relativistic limit

 

U Laha

Department of Physics, National Institute of Technology, Jamshedpur 831 014

Received 25 August 2003;revised 25 October 2004;
accepted 17 March 2005

Schrödinger equation with relativistic kinematics for light quarks has been studied in the representation space for Harmonic oscillator potential. The eigen functions and eigen values so obtained may prove useful for deeper understanding of N-N interaction.

Keywords: Light quarks, Schrödinger equation, Harmonic oscillator potential