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   Indian Journal of Pure and Applied Physics

 

ISSN: 0019-5596   CODEN:IJOPAU 41(8) 585-670(2003)
 VOLUME 41

NUMBER 8

AUGUST 2003

 

CONTENTS

 

The Physics of Elementary Particles and Fields

Signature of void probability scaling in high energy hadronic interactions

Dipak Ghosh*, Argha Deb, Prabhat Bandyopadhyay, Mitali Mondal, Jayita Ghosh, Swarnapratim Bhattacharya, Kanchan Patra & Dipak Maity

 

589

Nuclear Physics

Measurement of D2O-concentration in D2O-H2O mixture using neutron radiography technique

M N Islam*, M M Ahasan, M K Alam, M S Uddin & M A Zaman

 

593

Atomic and Molecular Physics

Normal coordinate analysis of 2-mercapto and 4,6-dihydroxy-2-mercapto pyrimidines

V Krishnakumar* & R John Xavier

 

597

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

Compressible couple-stress fluid permeated with suspended particles heated and soluted from below in porous medium

Sunil*, Divya, R C Sharma & Veena Sharma

 


602

Physics of Gases, Plasmas and Electric Discharges

Effect of trapped charges in sheath formation in non-isothermal plasma

G C Das* & P Kalita

 

612

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

Kinetics of thermoluminescent calcite

V Ponnusamy, V Ramasamy & M Dheenathayalu*

 

621

Linear and non-linear optical properties of antimony thiourea bromide crystals

S Govinda Bhat & S M Dharmaprakash*

627

Dielectric relaxation studies of binary mixtures of acetone and N,N dimethylacetamide in the benzene solutions using microwave absorption data

Vir Singh Rangra & D R Sharma*


630

dc Electrical properties of vacuum evaporated amorphous V2O5 thin films

M J A Sarkar* & M A R Sarkar

634

Yellow-green organic light emitting diodes based on poly (p-phenylene vinylene)/CdS heterojunction thin films

Lokendra Kumar, S K Dhawan, Mahesh Kumar, M N Kamalasanan* & Subhas Chandra


641

Superconducting properties of K0.2 Ba0.5Y0.3CuOx powder compacts

A M Ahmed

646

Optical and infrared absorption of gamma irradiated ternary silicate glasses containing NiO

Magda M I Khalil, Fatma H A Elbatal*, N Nada & S A Desouky

651

*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, August 2003, pp. 589-592

 

 

Signature of void probability scaling in
high energy hadronic interactions

Dipak Ghosh, Argha Deb, Prabhat Bandyopadhyay, Mitali Mondal,
Jayita Ghosh, Swarnapratim Bhattacharya, Kanchan Patra & Dipak Maity

 

 

The rapidity gap probability in the p-AgBr interactions at 200 GeV/c and p--AgBr interactions at 200 and 350 GeV/c have been studied in detail. The data indicate scaling behaviour of the void probability in the central rapidity domain, which hints the validity of the linked-pair approximation for the N-particle cumulant correlation function.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, August 2003, pp. 593-596

 

 

Measurements of D2O-concentration in D2O-H2O
mixture using neutron radiography technique

M N Islam, M M Ahasan*, M K Alam, M S Uddin & M A Zaman

 

This study is based on the optical density results measured from neutron radiographs of different samples of light water (H2O) and heavy water (D2O), taken separately, and also in the D2O-H2O mixture. A calibration curve was drawn through the results, extracted from a series of standard mixtures of D2O-H2O, with the known D2O concentration. The scale along the abscissa is to be explained as percentage of deuterium atoms present in the liquid compared with all atoms of hydrogen isotopes present. It may be concluded that, as D2O concentration added to light water increases, the optical density also increases, i.e., optical density is a function of D2O concentration. Neutron radiographs were then taken from two other samples of D2O-H2O mixture with different and unknown D2O concentration. Concentration of D2O was determined using the calibration curve via measurement of average optical density values.

  

  

Indian J Pure & Applied Physics

Vol. 41, August 2003, pp. 597-601

 

 

Normal coordinate analysis of 2-mercapto and
4,6-dihydroxy -2-mercapto pyrimidines

V Krishnakumar & R John Xavier*

 

 

The FTIR spectrum of 2-mercapto pyrimidine has been recorded in the region 4000-50 cm-1 and normal coordinate analysis of 2-mercapto pyrimidine and 4,6-dihydroxy -2-mercapto pyrimidine has been carried out by assuming Cs point group symmetry. All the modes of vibrations are assigned and calculations of potential energy distributions are also performed.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, August 2003, pp. 602-611

 

 

Compressible couple-stress fluid permeated with suspended particles heated and soluted from below in porous medium

Sunil & Divya and R C Sharma & Veena Sharma

 

A layer of a compressible couple-stress fluid permeated with suspended particles, heated and soluted from below in a porous medium is considered. For the case of stationary convection, the stable solute gradient and couple-stress have stabilizing effects, whereas the suspended particles and medium permeability have destabilizing effects on the onset of convection in the couple-stress fluid permeated with suspended particles, heated and soluted from below in a porous medium. The effect of compressibility is to postpone the onset of thermosolutal instability. Results are illustrated, graphically, by giving numerical values to the parameters. The system is stable for (cp/g)β > 1; cp, β and g denote specific heat at constant pressure, uniform temperature gradient and acceleration due to gravity, respectively. The stable solute gradient is found to introduce oscillatory modes in the system for (cp/g)β > 1, which were non-existent in its absence. Sufficient conditions for the non-existence of over-stability are also obtained.

 

  

 

Indian Journal of Pure & Applied Physics

Vol. 41, August 2003, pp. 612-620

 

Effect of trapped charges in sheath formation in
non-isothermal plasma

G C Das and P Kalita

 

 

The salient features of sheath formation in plasma with the effect of trapped electrons have been studied. The trapping process of electrons causes the generation of multi-temperature electrons in plasma medium, which modifies the plasma sheath formation. The study has been augmented through the derivation of a non-linear wave equation known as Sagdeev potential equation with the consideration of multi-temperature electrons. The numerical studies show that, the presence of high temperature electrons enhances the plasma sheath. Further, the levitation of dust dynamics along with its characteristic behaviours within the sheath have been studied, which in turn finds the formation of dust cloud atmosphere in plasma sheath. The study enables to calculate the sizes of the dust suspended in the sheath and thus, the forces acted on the dust grains.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, August 2003, pp. 621-626

 

 

Kinetics of thermoluminescent calcite

V Ponnusamy, V Ramasamy & M Dheenathayalu*

 

 

The thermo-stimulated luminescence (TSL) glow curve characteristics of five, blue coloured calcite samples of southern Tamilnadu are put to analysis. NTSL glow peaks are obtained for these samples. The glow curves of annealed (600 °C) and un-annealed samples, irradiated with gamma dose of 500 Gy show three peaks at 145, 255 and 345°C, respectively, recorded with linear heating rate of 10 °C/sec. The kinetic parameters such as activation energy (E), frequency factor (S) and order of kinetics (b) are evaluated, using partial heating, peak shape, isothermal and initial rise methods. The investigations show that, the trapping centres are not affected by the annealing procedure and it follows second-order kinetics. The activation energies have been determined.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, August 2003, pp. 627-629

 

 

Linear and non-linear optical properties of
antimony thiourea bromide crystals

S Govinda Bhat & S M Dharmaprakash

 

 

Single crystals of antimony thiourea bromide with molecular formula Sb[CS(NH2)2]2Br3 (ATB) have been grown in gels at ambient temperature. Linear optical properties of this material such as, refractive indices, birefringence and absorption characteristics are measured in the wavelength range 200-1400 nm. No dispersion of the birefringence has been observed within the experimental accuracy. Optical second harmonic generation (SHG) of Nd:YAG laser (l=1.064 mm) has been observed for ATB crystal.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, August 2003, pp. 630-633

 

 

Dielectric relaxation studies of binary mixtures of acetone and N, N-dimethylacetamide in the benzene solutions
using microwave absorption data

Vir Singh Rangra & D R Sharma

 

 

Using standard standing wave microwave techniques and following Gopala Krishna’s [Trans Faraday Soc, 33 (1957) 767] single frequency (9.88 GHz) concentration variational method, the dielectric relaxation times (t) and the dipole moments (m) of the binary mixtures of different molar concentrations of acetone (Ac) in binary mixtures of acetone and N,N-dimethylacetamide in benzene solutions have been calculated at different temperatures (25, 30, 35 and 40 °C. The energy parameters (rHe, rFe, rSe) for the dielectric relaxation process of binary mixtures containing 50% mole fractions of Ac have been calculated, at the respective given temperatures. Comparison has been made with the corresponding energy parameters for viscous flow. From the observations, it is found that the dielectric relaxation process like the viscous flow process can be treated as the rate process. On the basis of above studies, solute-solvent type of the molecular association can be predicted.

 

 

   

Indian Journal of Pure & Applied

Physics Vol. 41, August 2003, pp. 634-640

 

 

dc Electrical properties of vacuum evaporated
amorphous V2O5 thin films

M J A Sarkar and M A R Sarkar

 

 

Memory switching current versus voltage (I-V) characteristics of Al-V2O5 -Al sandwich devices for different V2O5 film thicknesses (40-350 nm) and temperatures (300-420 K) were measured and from these measured data, OFF state I-V characteristics were selected for the study of dc electrical properties to determine the type of conduction mechanism operating in the OFF state I-V characteristics. The OFF state log I-E˝ characteristics are found linear for the applied electric field E > 2.25´106 Vm–1. Values of activation energy DE obtained from the slope of log I-103/T curves for 0.2, 0.4, 1.0 and 4.0 V applied fixed voltages are found in the ranges 0.03-0.05 and 0.10-0.17 eV for the temperature intervals 300-350 K and 350-420 K, respectively. It was found from the dc data analyses that, the conduction mechanism operating in the OFF state I-V characteristics of Al-V2O5-Al sandwich devices appears to be predominated by the Poole-Frenkel emission.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, August 2003, pp. 641-645

 

 

Yellow-green organic light emitting diodes based
on poly (p-phenylene vinylene)/
CdS heterojunction thin films

Lokendra Kumar, S K Dhawan, Mahesh Kumar*, M N Kamalasanan &

Subhas Chandra

 

 

Thin film electro-luminescent devices based on organic materials are very popular for organic light emitting diodes (OLEDs) fabrication. The authors have polymerized PPV precursor solution from p-Xylenebis (tetrahydrothiophenium chloride) salt. Thin films of PPV were prepared by spin-coating, the precursor onto ITO substrates and curing it at 220 °C in the absence of oxygen. Organic light emitting diode structures were fabricated using ITO as the bottom electrode, PPV as an emitter layer as well as hole transport layer, CdS as an electron transport layer and aluminium as the cathode. In this configuration, CdS provides the advantage of excellent charge-transporting properties of an inorganic semiconductor. Electro-luminescence spectrum obtained from this hetero-junction device was similar to the emission spectrum of PPV. The devices give bright greenish-yellow electro-luminescence on application of about 10V under forward biased condition.

 

 

  

Indian Journal of Pure & Applied Physics

Vol. 41, August 2003, pp. 646-650

 

 

Superconducting properties of K0.2Ba0.5Y0.3CuOx powder compacts
A M Ahmed

 

 

Measurements of the electrical resistivity and thermoelectric power for sintered samples of K0.2Ba0.5Y0.3CuOx system were carried out. Two sets of the samples were prepared, the first set was sintered in air and the second set was sintered during flowing oxygen. The temperature dependence of the resistivity was found to be similar to that of metals. Further, the zero resistance was attained at 91-95 K depending on the sintering time. The author believes that, the prolonged sintering time caused oxygen vacancies (which may reside either along central-cage Cu-O chains) to become positively charged on trapping the hole, and thus enhance the superconductivity. The thermoelectric power of all samples was found to possess plus sign and decreases slightly with decreasing temperature, and then it falls down to zero, at the critical temperature (Tc).

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, August 2003, pp. 651-666

 

 

Optical and infrared absorption of gamma irradiated
ternary silicate glasses containing NiO

Magda M I Khalil, Fatma H A Elbatal, N Nada & S A Desouky

 

 

The optical and infrared absorption spectra of ternary silicate glasses containing NiO were studied systematically, as function of glass composition. The same properties were measured after successive gamma ray irradiation. The induced spectra and the rate of formation of the intrinsic defect of the base glass and the extrinsic defect due to the nickel ions were calculated. The experimental optical results were analysed and explained by assuming that, nickel exists in glass as divalent Ni ions in two different states of coordination, namely, octahedral and tetrahedral. The infrared spectra of the doped glasses reveal the same spectra of the undoped glasses retaining the main vibrational bands which indicate that the dopant oxide has no effect on the main structural building groups. The rates of formation and annihilation of the color centers produced by gamma irradiation are believed to approach saturation or equilibrium with prolonged irradiation.