Indian Journal of Pure and Applied Physics

 

ISSN: 0019-5596   CODEN:IJOPAU 41(5) 337-412(2003)
VOLUME 41

NUMBER 5

MAY 2003

 

CONTENTS

 

 

Atomic and Molecular Physics

Vibrational and normal coordinate analysis of thymine hydrochloride

V Krishnakumar* & M Arivazhagan

 

341

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

Computation of excess values of some acoustical parameters of binary/ternary liquid systems
using C-program

S B Kalyanaraman*, P Vasantharani & P Selvakumari

 


346

Condensed Matter: Structure, Mechanical and Thermal Properties

Crystal structure of tetrakis (imidazole) copper (II) bromide (CuBr2C12N8H12)

Pratyush Purkayastha*, B K Sarma & A N Talukdar

 

350

Correction term in total phonon conductivity

B K Singh, V J Menon* & K C Sood

354

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

Effect of axial index dip on the characteristics of broadband dispersion compensating optical fiber

Pramod R Watekar, M L N Goswami, S Kher, J C Biswas & H N Acharya*

 

358

Characterization of zirconium dioxide thin films prepared by cw CO2 laser-assisted evaporation

M G M Choudhury*, J S Kao, G R Lai & A G M R Ali

362

Formation of textured WS2 thin films by van der Waals rheotaxy process and their photoactivity

P S Patil*, E A Ennaoui, S Fiechter, H Tributsch & S B Sadale

369

Comparative absorption spectroscopy involving 4f-4f transitions to explore kinetics of complexation of Zn (II) with Er (III)-glutathione complex & compositional dependence of intensity parameters

Minaz A Gagnani, Ram S Shukla, Shreekala K Hari & Sudhindra N Misra*

374

Studies on the opto-electronic constants of alkali-halide crystals

 M A Salem

384

Anomalous Hall constant of heavy fermion systems

Sunil Panwar, Piyush Dua & Ishwar Singh*

389

Mossbauer, EPR and IR studies of some Fe doped dielectric materials

K K P Srivastava*, K K Sinha, D Banerji & Sajukta Ghose

393

Dielectric relaxation study of some binary liquid mixtures using frequency domain technique

T Kalaivani*, S Kumar & S Krishnan

398

Interdisciplinary Physics and Related Areas of Science and Technology

Ring oscillator based direct digital frequency synthesizer with improved spectral purity

B C Sarkar* & M K Mandal


402

News Scan

Paint anywhere LCD

Tarun Banerjee

 

408

*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, May 2003, pp. 341-345

 

Vibrational and normal coordinate analysis of thymine hydrochloride

V Krishnakumar

Department of Physics, Nehru Memorial College, Puthanampatti 621 007

and

M Arivazhagan

Department of Physics, JJ College of Engineering and Technology, Tiruchirapalli 620 009

 

Received 10 July 2002; revised 28 August 2002; accepted 31 January 2003

 

 

The FTIR and laser Raman spectra of thymine hydrochloride were recorded in the region 4000-100 cm-1 and the normal coordinate analysis has been carried out by assuming Cs point group symmetry. All the normal modes of vibrations are assigned and calculations of potential energy distribution are also performed.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, May 2003, pp. 346-349

 

 

Computation of excess values of some acoustical parameters of binary/ternary liquid systems using C-program

S B Kalyanaraman*, P Vasantharani & P Selvakumari

Department of Physics, Annamalai University, Annamalainagar, Tamil Nadu 608 002

Physics Wing, Directorate of Distance Education, Annamalai University, Annamalainagar, Tamil Nadu 608 002

 

Received 21 May 2002; revised 14 May 2003; accepted 10 April 2003

 

 

Excess values of acoustical parameters obtained from experimental measurements and theoretical calculations in binary/ternary liquid mixtures provide valuable information about the nature and strength of molecular interactions in the system. A brief explanation on the computation of the excess values of acoustical parameters using C-program is presented.

 

 

 

Indian J Pure & Applied Physics

Vol. 41, May 2003, pp. 350-353

 

 

Crystal structure of tetrakis (imidazole) copper(II) bromide
(CuBr2 C12 N8 H12)

Pratyush Purkayastha, B K Sarma & A N Talukdar

Department of Physics, Gauhati University, Guwahati, Assam 781 014

 

Received 20 December 2002; accepted 14 March 2003

 

 

The crystal and molecular structure of tetrakis imidazole copper (II) bromide (CuBr2C12N8H12) has been investigated from three-dimensional intensity data. The two imidazole rings bonded to the central Cu atom through the respective N atom, which constitutes one-half of the asymmetric unit of the centrosymmetric structure under consideration. The distance between CuBr¯ ion is found to be 3.376(1)Å which excludes the possibility of formation of any covalent bond between them.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, May 2003, pp. 354-358

 

 

Correction term in total phonon conductivity

B K Singh, V J Menon & K C Sood

Department of Physics, Banaras Hindu University, Varanasi 221 005

 

Received 5 September 2002; accepted 14 January 2003

 

 

In Holland’s two-mode thermal conduction theory, the correction term Kc (which represents the effect of momentum conserving normal processes in the Callaway model) was treated under certain limitations. To be specific, (i) his starting expression of Kc had an unwarranted temperature-dependent coefficient, (ii) the Taylor expansion of integrand was not quite satisfactory, and (iii) use of the same functional form of the three phonon normal process relaxation rate at low and high frequencies was not justified. These deficiencies were overcome by starting with the correct expression of Kc, doing a careful Taylor expansion and also incorporating the umklapp processes, apart from the normal ones. The relative importance of Kc is illustrated numerically for Si and LiF.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, May 2003, pp. 358-361

 

 

Effect of axial index dip on the characteristics of
broadband dispersion compensating optical fiber

Pramod R Watekar, M L N Goswami, S Kher*, J C Biswas† & H N Acharya

Optical Fiber Unit, Central Research Facility,

†Department of Electronics and Electrical Communication Engineering

Indian Institute of Technology, Kharagpur 721302

*Centre for Advanced Technology, Indore

 

Received 9 September 2002; accepted 17 March 2003

 

 

The experimental studies of the characteristics of dispersion compensating optical fiber (DCF) with reference to its axial index dip have been reported. The DCF characteristics such as chromatic dispersion, dispersion slope, mode field diameter, bending loss and cut-off wavelength have been altered due to axial index dip in the DCF. This work is useful for the optical fiber communications.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, May 2003, pp. 362-368

 

 

Characterization of zirconium dioxide thin films
prepared by cw CO2 laser-assisted evaporation

M G M Choudhury†, J S Kao*, G R Lai* & A G M R Ali†

Department of Physics, University of Rajshahi, Rajshahi-6205, Bangladesh

†Department of Physics, University of Rajshahi, Rajshahi, Bangladesh

*Precision Instrument Development Center (PIDC), Hsinchu, Taiwan

 

Received 5 June 2002; revised 21 March 2003; accepted 9 April 2003

 

 

Zirconium dioxide thin films have been deposited by cw CO2 laser-assisted evaporation on Si(100), quartz and optically polished glass substrates at different substrate temperature. Films were grown in oxygen, under partial pressure. The surface morphology of the films has been observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the structure has been studied by X-ray diffraction (XRD). The optical bandgap has been calculated from transmission spectra, taken in the UV range. The dc dark conductivity has been investigated in the temperature range 30-130 C. The SEM micrographs show that, the film surfaces are smooth and polycrystalline and grows in a well-aligned columnar structure. XRD observations revealed that, the structure of the films deposited at 250 C substrate temperature is tetragonal having lattice constants a = 0.5074 nm and c = 0.572 nm. The bandgap evaluated from optical spectra is  5.25 eV. The dc conductivity shows linear variation with temperature with the experimental temperature range, suggesting an activated process, having single activation energy.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, May 2003, pp. 369-373

 

 

Formation of textured WS2 thin films by
van der Waals rheotaxy process and their photoactivity

P S Patila, E A Ennaouib, S Fiechterb, H Tributschb & S B Sadalea

aDepartment of Physics, Shivaji University, Kolhapur 416 004

bHahn-Meitner Institute, Glienicker Strasse 100, 14109 Berlin, Germany

 

Received 1 August 2002; revised 11 February 2003; accepted 26 March 2003

 

 

Photoactive thin films of tungsten disulphide (WS2) have been prepared by sulphurization of tungsten trioxide (WO3) thin films. WO3 films have been deposited in an inert atmosphere onto the pre-deposited Ni coated quartz substrates by using an ultrasonic spray pyrolysis technique (USP). Subsequently, the WO3 films have been treated at 700 oC in a sealed quartz ampoule filled with elemental sulphur and 0.2 bar N2/H2 forming gas for about 6 hr. The films have been investigated by using X-ray diffractometer (XRD), scanning electron microscopy (SEM), and optical absorption techniques. The photoactivity has been measured using time-resolved microwave conductivity (TRMC) technique. For comparison, the results of WS2 films grown on quartz substrates without pre-deposited nickel layer have been given.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, May 2003, pp. 374-383

 

 

Comparative absorption spectroscopy involving 4f-4f transitions to explore kinetics of complexation of Zn(II) with Er(III)-glutathione complex & compositional dependence of intensity parameters

Minaz A Gagnani1, Ram S Shukla1, Shreekala K Hari2 & Sudhindra N Misra2

1Central Salt & Marine Chemicals Research Institute, Bhavnagar, Gujarat 364 002

2Department of Chemistry, Bhavnagar University, Bhavnagar, Gujarat 364 002

 

Received 8 April 2002; revised 10 December 2002; accepted 14 February 2003

 

 

The kinetic and spectroscopic investigations on complexation of Zn(II) with Er2(GSH)2(H2O)4 1 (GSH = reduced glutathione) to form Er2(GSH)2Zn(H2O)6 complex 2 have been performed at 30 C by following five, 4f-4f sensitive transitions of lanthanide Er(III), 4I15/ 2  4G11/2 , 4I15/2  4F7/2 , 4I15/2  2H11/2 , 4I15/2  4F9/2 and 4I15/2  4I11/2 in water as well as in equimolar mixture of DMF and water. Performances of all the five bands were found to be competently sensitive, on the basis of kinetic studies done by following the changes in the intensity (absorbance, molar absorptivity) and intensity parameters (oscillator strength P and Judd-Ofelt T intensity). Kinetics showed first order dependence in terms of concentrations of Zn(II) and complex 1 on the rate of formation of complex 2. In order to support the kinetic and spectroscopic observations, complex 1 and 2 were synthesized also, and were characterized by C, H, N, S, and elemental analysis; UV/VIS, NMR and IR techniques. Kinetic, mechanistic and spectroscopic aspects of the complexation reaction are presented and discussed.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, May 2003, pp. 384-388

 

 

Studies on the opto-electronic constants of alkali-halide crystals

M A Salem

Physics Department, Faculty of Science, Azhar University, Nasr-City, Cairo, Egypt

E.mail: salemazhar@yahoo.com

 

Received 1 July 2002; accepted 21 March 2003

 

 

Correlation between refractive index (n) of alkali-halide crystals and both energy band gap (Eg) and Pauling’s electronegativity difference (X) have been studied. The following relations are proposed for estimating the refractive index (n): n2+C=A/ Eg1/2 and n2+C=E/(X)0.425, where A, C and E are numerical constants. In addition, an interrelation between the energy band gap (Eg) and electronegativity difference (X) has also been proposed. This relation reads as: Eg=4.45(X)0..85. The estimated values of the refractive index are utilized to evaluate the electronic polarizability of alkali-halides (e) by applying Lorentz-Lorentz formula. The computed values of refractive index, energy gap and electronic polarizability are compared with the literature ones.

 

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, May 2003, pp. 389-392

 

 

Anomalous Hall constant of heavy fermion systems

Sunil Panwar

Department of Basic Sciences, College of Engineering & Technology, Gurukul Kangri University, Hardwar

and

Piyush Dua & Ishwar Singh

Department of Physics, Indian Institute of Technology, Roorkee

 

Received 12 June 2002; revised 29 January 2003; accepted 20 March 2003

 

 

The large anomalous Hall constant of heavy fermion systems can be understood using Periodic Anderson model. A variational method in this work to study temperature variation of Hall constant RH of cerium compounds has been used. The skew scattering plays a dominant role in deciding RH in these compounds. The scattering phase shift is strongly magnetic field dependent and the Hall constant is expressible in terms of magnetic susceptibility.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, May 2003, pp. 393-397

 

 

Mossbauer, EPR and IR studies of some Fe doped dielectric materials

K K P Srivastava, K K Sinha, D Banerji* & Sajukta Ghose*

Department of Physics, T M Bhagalpur University, Bhagalpur 812 007

*Department of Physics, Calcutta University, Kolkata 700 001

 

Received 4 October 2002; revised 3 March 2003

 

 

The PbTiO3 and BaTiO3 are well-known ferroelectrics of ABO3 type perovskite structure with dielectric constants of about a few hundred. Several ceramics synthesised partially with other divalent, tetravalent and pentavalent atoms show high dielectric constants and are useful for electronic components and hence their characterisation is important. Mossbauer, EPR and IR methods can be quite effective provided these ceramics contain a small percentage of Fe which produces spectra depending upon its valence state and local symmetry. The spectra of such lead and strontium titanates show the presence of high spin Fe(III) valence state as indicated by QS, IS and g-values. The IR band at around 600 cm-1 seems to originate from FeO6 polyhedron besides the usual absorption band at around 410 cm-1 coming from the TiO6 polyhedron.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, May 2003, pp. 398-401

 

 

Dielectric relaxation study of some binary liquid mixtures
using frequency domain technique

T Kalaivani, S Kumar & S Krishnan

Department of Physics, Annamalai University, Annamalainagar 608 002

 

Received 20 September 2002; revised 10 April 2003

 

 

Dielectric relaxation studies have been carried out in three binary liquid systems namely hexanol, heptanol and octanol with benzene solution. The oscillating frequency of X- band microwave bench is at 9.36 GHz. The orientation of molecular dipoles have been identified by the Kirkwood linear correlation factor (g). The relaxation time () is obtained by both Higasi’s and Cole-Cole method. The dipole moments of the systems are determined by Higasi’s and Gopalakrishna’s method. The activation energies due to the relaxation process (F) and the viscous flow (F) are calculated.

 

 

 

Indian J Pure & Applied Physics

Vol. 41, May 2003, pp. 402-407

 

 

Ring oscillator-based direct digital frequency synthesizer
with improved spectral purity

B C Sarkar & M K Mandal

Radionics Laboratory, Physics Department, Burdwan University, Golapbag, Burdwan, (WB) 713 104

[e-mail: vishbdn@vsnl.net]

 

Received 19 August 2002; accepted 13 March 2003

 

 

Conventional direct digital frequency synthesizers (DDFS), designed using accumulators and phase registers, normally employ a clock signal of a fixed period. This results in synthesized signals having instantaneously varying time periods. The present work employs a ring oscillator (RO) to provide the clock signal and the time period of the RO is properly varied to obtain fixed period, synthesized output signal. Experimental results are incorporated to prove the validity of the design modification algorithm.

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 41, May 2003, pp. 408-408

 

 

NEWS SCAN

 

Paint anywhere LCD

 

 

A conventional LCD (liquid crystal display) screen consists of two glass plates having conducting and alignment coatings with a 5-μm-thick layer of liquid crystal – generally a mixture of pentyl cyanobiphenyl with some other cyanobiphenyl molecules in between. Orientation of the liquid crystals are determined by the electric field in the conducting layer applied on the inner surface of the glass substrates and results into different shades leading to formation of an image. With the passage of time, the glass plates were replaced by plastic ones that are generally unbreakable, leading to easy mass production of LCDs, having, however, the same basic sandwich structure. Nonetheless, the process is laborious, time consuming, and hence, expensive. That apart, since the substrate is rigid, design flexibility regarding size and shape is minimal.