Indian Journal of Pure and Applied Physics

 

 

 

ISSN: 0019-5596  

CODEN:IJOPAU 41(1) 1-84(2003)

VOLUME 41 

NUMBER 1   

JANUARY  2003

 

 

CONTENTS

 

Nuclear Physics

Study of neodymium mass chain in the variation after projection framework

R K Bhat, Rani Devi & S K Khosa*

 

 

5

Atomic and Molecular Physics

Hybrid theory for one-dimensional binary alloys with local environment disorder

Sureshchandra J Gupta* & Rajalaxmi Das

 

 

15

Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics and Fluid Dynamics

Ultrasonic behaviour of substituted acrylo phenone and its complexes

C C Deshmukh*, A G Doshi & C M Deshmukh

 

21

MHD free convection and mass transfer flow with Hall current, viscous dissipation, Joule heating and thermal diffusion

Ajay Kumar Singh

 

24

Physics of Gases, Plasmas and Electric Discharges

Relativistic stimulated Raman Scattering in a plasma channel

J K Sharma, J Parashar* & A S Mehta

 

73

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

Effect of hydrostatic pressure on series resistance of Au/n-GaAs Schottky diodes

Güven Çankaya & Nazim Uçar*

 

36

Dielectric behaviour and trapping in praseodymium doped calcium sulphide phosphors

R N Dubey, M S Qureshi, Vijay Singh, Manoj Tiwari* & S J Dhoble

40

Study of dipole moment of 18-crown-6 in CCl4 solutions at 298.15 K

K J Patil * P K Patil, R R Kolhapurkar & D H Dagade

46

Degradation of photon distribution and its effect on high frequency performance of 2D hot electrons in CdS quantum wells

Subir Kumar Sarkar

 

52

Temperature dependence of dielectric relaxation of rigid polar molecules acetophenone, pyridine and their mixtures in dilute solutions of benzene

K K Gupta, A K Bansal*, P J Singh & K S Sharma


57

Low cost PC based I-V measurement set-up for ion implanted semiconductor devices

K V Sukhatankar, A M Narasale* M M Belekar & B M Arora

64

News Scan

Unraveling the Sun, neutrino and X-ray astronomy

Tarun Banerjee

 

77

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

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, January  2003, pp. 5-14

 

 

Study of neodymium mass chain in the variation after projection framework

R K Bhat, Rani Devi & S K Khosa

Department of Physics and Electronics, University of Jammu, Jammu 180 006

 

Received 1 March 2002; revised 20 June 2002; accepted 14 August 2002

 

 

Variation after projection (VAP) calculations in conjunction with Hartree Bogoliubov (HB) ansatz have been carried out for 128-154Nd mass chain. In this framework, the yrast spectra, B(E2) transition probabilities and occupation numbers for various shell model orbits have been obtained. The observed shape transition encountered in going from 148Nd to 150-154Nd is seen to arise due to enhanced occupation of low k-components of (h11/2)p orbit, increased polarization of (d5/2)p orbit and increase in the occupation of (i13/2)n and (h11/2)n orbits.

 

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, January 2003, pp. 15-20

 

 

Hybrid theory for one-dimensional binary alloys
with local environment disorder

Sureshchandra J Gupta

Department of Physics, University of Mumbai, Mumbai  400 098

and

Rajalaxmi Das

Department of Physics, BVIT, Navi-Mumbai, Mumbai  400 614

 

Received 15 June 2002; revised 23 September 2002; accepted 25 November 2002

 

 

The vibrational frequency spectra of the random one-dimensional binary alloys AcB1-c have been accurately predicted by a hybrid theory which combines the single-site coherent potential approximation (CPA) with the statistical theory of small clusters embedded in a defect lattice potential. It takes advantage of the assets of both the numerical calculations of Dean1,2 [Rev Mod Phys, 44 (1972) 127; Proc Roy Soc A, 260 (1961) 263] and the statistical-analytical approaches of mean- field approximations. It uses the fundamental properties of finite clusters of atoms in order to properly determine the short-ranged correlations in atomic motions. The local environment effects on the density of states are included, by considering the system as a multi-component system with different neighbour compositions. The theory of the authors is an alternative to multi-site CPA and the embedded cluster theory.

 

 

 

 

 

Indian J Pure & Applied Physics

Vol. 41, January  2003, pp. 21-29

 

 

Ultrasonic behaviour of substituted acrylo phenone and its complexes

C C Deshmukh, A G Doshi & C M Deshmukh1

Vidyabharti Institute of Research and Post Graduate Studies in Science and Management, Amravati

Shri Shivaji Agriculture College , Amravati

 

Received 3 May 2002, revised 9 September 2002; accepted 25 November 2002

 

 

Ultrasonic velocity and density measurements on 3-(2-hydroxy-3-nitro-5-chlorophenyl)-5-(2-furyl)-D2-pyrazoline and its complexes with Fe (II), Ni (II), Co (II), Cu (II), Mn (II) and Cr (II) in acetone as a solvent, have been carried out at 298.5 K. Different acoustic properties like apparent molar volume, apparent molar compressibility, inter-molecular free- length, etc. have been determined. The parameters so obtained have been interpreted in terms of solute-solvent and solute-solute interactions.

 

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, January 2003, pp. 24-35

 

 

MHD free convection and mass transfer flow with Hall current, viscous dissipation, Joule heating and thermal diffusion

Ajay Kumar Singh

Department of Mathematics, C L Jain (PG) College, Firozabad 283 203

 

Received 29 April 2002; revised 15 July 2002; accepted 2 August 2002

 

 

The combined effect of Hall current, viscous dissipation, Joule heating and thermal diffusion on the hydromagnetic free convection and mass transfer flow of an electrically conducting, viscous, incompressible fluid past an infinite vertical porous plate, has been studied. The governing partial differential equations of this MHD-free convective boundary layer flow are reduced to non-linear ordinary differential equations by introducing suitable similarity transformations. The problem is solved analytically, and the velocity, temperature and concentration profiles are presented graphically. The skin-friction coefficient, the Nusselt number and the Sherwood number are calculated and presented. Finally, a thorough discussion has been presented for the results obtained.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, January 2003, pp. 73-76

 

NOTE

 

Relativistic stimulated Raman scattering in a plasma channel

J K Sharma , J Parashar & A S Mehta

Department of Applied Physics, Samrat Ashok Technological Institute, Vidisha (MP) 464 001

 

 

Received 15 January 2002; revised 23 July 2002; accepted 5 August 2002

 

An intense laser radiation propagating in a plasma channel undergoes stimulated Raman scattering (SRS) and produces a Langmuir and a sideband electromagnetic wave. At higher laser power, relativistic effects become important. It has been found that, the growth rate is dependent on the localization of the Langmuir wave. The growth rate of the process is maximum near the axis.

 

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, January 2003, pp. 36-39

 

 

Effect of hydrostatic pressure on series resistance
of Au/n-GaAs Schottky diodes

Güven Çankaya1 & Nazim Uçar2

1Atatürk University, Faculty of Sciences and Arts, Physics Department, Erzurum, Turkey

2 Süleyman Demirel University, Faculty of Sciences and Arts, Physics Department, Isparta, Turkey

 

Received 4 October 2002; accepted 26 November 2002

 

 

Au/n-GaAs Schottky barrier diodes have been fabricated. The series resistance has been measured as a function of hydrostatic pressure using the current-voltage (I-V) technique. It has been found that the series resistance increases with increasing hydrostatic pressure.

 

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, January 2003, pp. 40-45

 

 

Dielectric behaviour and trapping in praseodymium doped
calcium sulphide phophors

R N Dubey & M S Qureshi

Department of Physics, Maulana Azad College of Technology, Bhopal 462 007

and

Vijay Singh & Manoj Tiwari

Department of Physics, Regional Institute of Education, Bhopal 462 013

and

S J Dhoble

Department of Physics, Kamla Nehru College, Nagpur 440 013

 

Received 20 May 2002; revised 11 November 2002; accepted 13 November 2002

 

 

Loss tangent, loss capacitance and relaxation times are generally evaluated by simultaneous measurement of ac conductance and ac capacitance for dielectrics and semiconductors in different shapes, sizes and states. Here, a new method is suggested to evaluate all the above parameter using Debye equations and measuring capacitance of phosphor cells at different audio frequencies. Relaxation time at room temperature comes out to be in microseconds. This may be due to electron traps 0.7 eV below the conduction band. This dielectric study leads to the same trap level position as found by many workers in thermally stimulated luminescence (TSL) and thermally stimulated conductivity (TSC) as well as phosphorescence decay mechanism.

 

  

   

 

Indian Journal of Pure & Applied Physics

Vol. 41, January 2003, pp. 46-51

 

 

Study of dipole moment of 18-crown-6 in CCl4
solutions at 298.15 K

K J Patil*, P K Patil, R R Kolhapurkar & D H Dagade

Department of Chemistry, Shivaji University, Kolhapur 416 004

 

Received 14 June 2002;

 

 

Dielectric constant (e), density (d) and refractive index (n) measurements at 298.15 K for solutions of 18-crown-6 in CCl4 (0.5 to 25 ´ 10-3 weight fraction of solute) have been reported. The data, along with partial molar volume data for solute are subjected to analysis using various equations to obtain solute polarization and dipole moment values at finite and infinitely dilute concentrations. The dipole moment value of 3.5 D has been compared with gas-phase value and the values in solutions of benzene and cyclohexane, reported earlier. The unexpected large value of dipole moment obtained has been discussed in terms of conformation adopted by the cyclic polyether in a solvent environment. It is further explained that, in solution phase if 18C6 molecules exist in Ci symmetry conformation (this cannot have dipole moment), the atomic polarization via –CH2– chains must be making large contribution to account for the observed solute polarization.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, January 2003, pp. 52-56

 

 

Degradation of photon distribution and its effect on high frequency performance of 2D hot electrons in CdS quantum wells

Subir Kumar Sarkar

Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata 700 032

[E-mail: su_sarkar@hotmail.com]

 

Received 22 February 2002; revised 27 June 2002; accepted 31 October 2002

 

 

The high frequency performance of two-dimensional hot electron in CdS quantum wells is studied in the framework of the heated, drifted Fermi-Dirac distribution function, incorporating the relevant scattering mechanisms. The effects of non-equilibrium longitudinal optic (LO) phonons are also included in the calculations. The influences of large – q LO phonon and electron – LO phonon interactions at low qLz are also studied. The ac mobility normalized by its dc value is found to decrease with increasing frequency of the applied field beyond about 100 GHz while the drift velocity lags behind the applied field above, about 10 GHz. The degradation of phonon distribution enhances the 3 dB cut-off frequency at which the ac mobility drops to 0.707 of its low frequency value.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, January 2003, pp. 57-63

 

 

Temperature dependence of dielectric relaxation of
rigid polar molecules acetophenone, pyridine and
their mixtures in dilute solutions of benzene

K K Gupta, A K Bansal, P J Singh & K S Sharma*

Department of Physics, M S J College, Bharatpur 321 001

 

Received 25 June 2002; revised 3 October 2002; accepted 26 November 2002

 

 

The dielectric absorption studies of acetophenone, pyridine and their binary mixtures, both consisting of rigid molecules, have been studied at 8.93 GHz in the dilute solutions of benzene at different temperatures. The relaxation times, dipole moments, thermodynamical parameters, viz. free energy, enthalpy and entropy of activation have been calculated from the dielectric data. The relaxation time (t0) of the single component agrees well with literature values. The experimental values of relaxation time (t0) of the dipolar mixture have been compared with the theoretical values obtained by employing different methods. The non-linear behaviour of m2 versus mole fraction is explained on the basis of solute-solute molecular association between these two-polar rigid molecules. The values of the molar entropy for the relaxation process indicate that, the cooperative orientation of the molecules in the single component system is retained in the mixture also.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, January 2003, pp. 64-72

 

 

Low cost PC-based I-V measurement set-up for ion implanted semiconductor devices

K V Sukhatankar1, A M Narasale1, M M Belekar1 & B M Arora2

1Department of Physics, University of Mumbai, Vidyanagari, Mumbai 400 098

2Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005

 

Received 7 January 2002; revised 24 October 2002; accepted 8 November 2002

 

 

A low cost PC-based system to measure, record and plot current-voltage characteristics of the ion implanted semiconductor samples has been designed and developed. The various modules of the system are programmable voltage source, current to voltage converter and data acquisition system. The programmable voltage source makes use of two 12-bit digital to analog converters, a summing amplifier, a programmable amplifier and a high voltage amplifier stage. This voltage source can be programmed over a voltage span of ± 20 V, in any step voltage desired, up to a minimum step of ± 10 mV. Data acquisition system is developed using a sample and hold circuit, a programmable amplifier and a 12-bit analog-to-digital converter. The gain of programmable amplifier stage can be set through I/O signals from PC. The current can be measured in five different ranges from (0-1mA) to (0-10mA) and the current resolution of the system is ± 0.5 nA. User-friendly software has been developed in Turbo C, in an interactive mode, to store the I-V data and plot it either simultaneously or later on whenever required. The number of current readings per voltage step can be programmed through the software and their average is recorded. The system shows good accuracy, repeatability, reliability and is relatively inexpensive. The designed and fabricated PC-based I-V set-up has been used to study the I-V characteristics of n+-GaAs substrates implanted with 70 MeV 120Sn ions. Single crystal n+-GaAs substrates of <100> orientation have been implanted at room temperature with 120Sn ions at 70 MeV energy to three different doses of 1 ´ 1012, 1 ´ 1013 and 1 ´ 1014 ions/cm2. The implanted samples were isochronally annealed for 10 min in a RTA system at different temperatures in the range 100-300 °C. The room temperature I-V curves for the as-implanted sample and samples annealed at different temperatures were recorded and their room temperature resistance values are estimated from them. The I-V behaviour of these samples has been found to be dominated by radiation-induced defect states in the GaAs substrates.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, January 2003, pp. 77-80

 

 

NEWS SCAN

Unraveling the Sun, neutrino and X-ray astronomy

 

 

Man's first gods were the forces of nature. Terrifying and unpredictable, they were feared rather than revered by our ancestors. They also worshipped gods that were beautiful to behold, luminous and colourful. In ancient times Apollo was the Sun God of the Greeks and the Romans. Amon-Ra was believed to be the Sun God in ancient Egypt and the lord of the universe. The Hindus also worship the Sun by chanting the mantra:

 

Om jabaakusuma sankaasham kaashyapayam mahaadyutim

Tamorim sarvapaapaghnam pranato-smi divaakaram

Om suryaaya namah