Indian Journal of Pure and Applied Physics

Total visitors:1,946 since 10-10-05

 

 ISSN: 0019-5596

CODEN: IJOPAU 43 (10) 725-810

VOLUME  43

NUMBER 10

OCTOBER 2005

CONTENTS

Nuclear Physics

 

Cross- section measurements of (n, 2n), (n, p) and (n, α) reactions on some selenium isotopes near En=14 MeV

Guo-zhu He, Zhong-jie Liu, Jun-hua Luo& Xiang-zhong Kong*

729

 

Pulse height defect in ion implanted silicon detector for heavy ions with Z = 6 - 28 in the energy range~ 0.25 - 2.5 MeV/u

P K Diwan*, V Sharma, Shyam Kumar & D K Avasthi

 

733

Atomic and Molecular Physics

 

Calculation of Franck-Condon factors and r-centroids using isospectral Hamiltonian approach

Anil Kumar & C Nagaraja Kumar*

738

Photo physical properties of 8-hydroxy quinoline

L R Naik  & N N Math*

743

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

 

Ultrasonic study of induced dipole-dipole interactions in binary liquid mixtures

V Kannappan* & R Jaya Santhi

750

Ultrasonic study of 1-butanol in pyridine with benzene

G Arul & L Palaniappan*

755

Condensed Matter: Structure, Mechanical and Thermal Properties

 

Analysis of inverted type high pressure equations of state for solids

S Digpratap, K Sushil & B P Singh*

759

Growth mechanism of carbon nanotubes deposited by electrochemical technique

S K Mandal, S Hussain & A K Pal*

765

Theoretical study of ABO3 type perovskite with reference to KNbO3

Kuldeep Singh, S C Bhatt* & B S Semwal

772

 

 

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

 

Dielectric dispersion and microwave dielectric study of marbles in support of radar investigations

R J Sengwa* & A Soni

777

Segregation behaviour of trace metal impurities during ultra high purification of gallium by zone refining

U Rambabu*, N R Munirathnam, R C Reddy & T L Prakash

783

Study of impedance spectroscopy conducting polymer prepared with the use of water soluble support polymer

D K Ray, A K Himanshu & T P Sinha*

787

Effect of charge bump on the series resistance and microwave properties of Si n+np+ IMPATT diode at X-band

P De

794

Realization of voltage-mode and current-mode biquad filters using current feedback amplifiers

N A Shah*, M F Rather & S Z Iqbal

799

——————

*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, October 2005, pp. 729-732

 

 

 

Cross-section measurements of (n, 2n), (n, p) and (n, α) reactions on some
selenium isotopes near En=14 MeV

 

Guo-zhu He, Zhong-jie Liu, Jun-hua Luoa & Xiang-zhong Kong*

Department of Modern Physics, Lanzhou University, Gansu Lanzhou 730000, P R China

aDepartment of Physics, Hexi University, Gansu zhangye 734000, P R China

Received 21 February 2005; accepted 21 July 2005

Cross-sections for 82Se(n, 2n)81mSe, 82Se(n, 2n)81gSe, 76Se(n, 2n)75Se, 78Se(n, p)78As, 76Se(n, p)76As, 74Se(n, p)74As and 80Se(n, α)77Ge reactions have been measured for neutron energies from 13.5 to 14.6 MeV using activation technique. Neutrons were produced by reaction 3H(d, n)4H and neutron flux were monitored by reaction 93Nb(n, 2n) 92mNb. The results of the present work are compared with the values of previous researchers.

Keywords: Selenium isotopes, Gamma spectroscopy, HPGe detector, Neutron energies

IPC Code: G01T

Indian Journal of Pure & Applied Physics

Vol. 43, October 2005, pp. 733-737

 

 

 

 

Pulse height defect in ion implanted silicon detector for heavy ions with Z = 6-28 in the energy  range ~ 0.25-2.5 MeV/u

P K Diwan1, V Sharma2, Shyam Kumar2 & D K Avasthi3

1Department of Physics, U.I.E.T., Kurukshetra University, Kurukshetra 136 119

2Department of Physics, Kurukshetra University, Kurukshetra 136 119

3Nuclear Science Centre, P.O. Box 10502, New Delhi 110 067

Received 29 December 2004; revised 10 June 2005; accepted 3 August 2005

The response of ion implanted silicon detector has been studied for heavy ions with Z = 6-28 in the energy range ~ 0.25 - 2.5 MeV/u utilizing the 15UD Pelletron accelerator facility at Nuclear Science Centre, New Delhi, India. The variation of pulse height in ion implanted silicon detector with projectile’s atomic number and its energy have been investigated. It has been observed that pulse height-energy calibration for a given projectile is described well by a linear relationship indicating no pulse height defect with the variation in energy for specific Z projectile. Pulse height defect has been found to increase with increasing projectile atomic number. The mean slope of the collected charge signal versus projectile energy depends significantly on the atomic number of the projectile.

Keywords: Pulse height defect, Heavy ions, Silicon detector, Pelletron accelerator

IPC Code: H05H6/00, H01L


 

Indian Journal of Pure & Applied Physics

Vol. 43, October 2005, pp. 738-742

 

 

 

 

Calculation of Franck-Condon factors and r-centroids using isospectral Hamiltonian approach

 

Anil Kumar & C Nagaraja Kumar*

Department of Physics, Panjab University, Chandigarh 160 014

Received 5 April 2005; accepted 22 July 2005

The calculation of Franck-Condon factors is of interest to study the vibrational transitions in diatomic molecules. Morse potential is one of the commonly used models for these calculations. Using isospectral Hamiltonian approach, a family of isospectral potentials, which have the same energy eigenvalues as that of Morse potential has been obtained. The eigenfunctions for this family of isospectral potentials are different from that of the original potential. The Franck-Condon factors and r-centroid values obtained using the deformed wavefunctions can be varied to match the experimental data.

Keywords: Isospectral Hamiltonian, Franck-Condon factor, r-Centroid

IPC Code: G09B23/20

Indian Journal of Pure & Applied Physics

Vol. 43, October 2005, pp. 743-749

 

 

 

Photo physical properties of 8-hydroxy quinoline

L R Naik & N N Math*

Department of Physics, Karnataka University, Dharwad 580 003

Received 3 May 2005; accepted 18 August  2005

The steady state absorption, fluorescence excitation and emission spectra of 8-hydroxy quinoline (8-HQ) have been studied in a wide range of solvents of varying dipole moments. The dependence of fluorescence emission on concentration and excitation wavelength indicates the existence of two different emitting species in equilibrium. The fluorescence quantum yield exhibits a substantial solvent dependence. The high quantum yield observed in polar aprotic solvents such as dimethyl formamide and dimethyl sulphoxide might be due to severe overlapping of electronic transitions of various species/single species. The fluorescence and emission spectra of 8-HQ in various solvents exhibit dual fluorescence in the region 330-410 nm. The fluorescence emission of 8-HQ in pure dimethyl formamide, dimethyl sulphoxide and propanol solvents measured as a function of concentration in the range 10´10-6 to 5´10-4 mol dm-3 displays a clear iso-emissive point at 395 nm while in binary mixture of propanol and dimethyl formamide, iso-emissive point is obtained around 410 nm for excitation wavelength of 290 nm. This finding reveals the formation of two stoichiometric hydrogen-bonding complexes, namely, 1:1 and 1:2 complexes in the ground and excited state.

Keywords: Absorption, Fluorescence excitation, Emission spectra, H-bonding complexes, Monomers, Dimers

IPC Code: C09K9/00


 

Indian Journal of Pure & Applied Physics

Vol. 43, October 2005, pp. 750-754

 

 

 

 

Ultrasonic study of induced dipole-dipole interactions in binary liquid mixtures

 

V Kannappan# & R Jaya Santhi*

#Postgraduate and Research Department of Chemistry, Presidency College, Chennai 600 005

*Department of Chemistry, Auxilium College, Vellore 632 006

Received 28 February 2005; revised 14 June 2005; accepted 8 August 2005

The induced dipole-dipole interactions have been studied in binary liquid mixtures of pyridine, chlorobenzene, bromobenzene and nitrobenzene with p-xylene by measuring the ultrasonic velocity (U), density (ρ) and viscosity (η) values at 298 K at various concentrations. Acoustical parameters such as adiabatic compressibility (β), free volume (Vf), internal pressure (πi), intermolecular free length (Lf), absorption coefficient (α/f2), relaxation time (τ), Rao constant (R), cohesive energy (CE) and molecular interaction parameter with respect to velocity (χU) have also been calculated. The acoustical parameters can be used to assess the strength of induced dipole-dipole interactions in the four systems studied. The strength of dipole-induced dipole attractions correlates with dielectric constant and dipole moment of the polar compounds.

Keywords: Interactions, Induced dipole, Substituted benzene, Molefractions

IPC Code: B01J19/10

 

 

Indian Journal of Pure & Applied Physics

Vol. 43, October 2005, pp. 755-758

 

 

 

 

Ultrasonic study of 1-butanol in pyridine with benzene

 

G Arul & L Palaniappan

Department of Physics (DDE), Annamalai University, Annamalainagar 608 002

Received 22 November 2004; revised 14 March 2005; accepted 19 July 2005

Sound velocity, density and viscosity have been measured in the ternary mixtures of 1-butanol in pyridine with benzene at 303K. Some of the acoustical parameters such as adiabatic compressibility, free length, free volume and internal pressure are calculated from the measured data using the standard relations. The trend shown by the excess parameters of free volume and internal pressure is peculiar that both are negative and in increasing order confirms that the associative nature of alcohol disturbs the molecular symmetry available in benzene molecule. The reduction in the cohesion of dipolar pyridine is also noticed.

Keywords: Sound velocity, Viscosity, Adiabatic compressibility, Free length, Free volume, Internal pressure

IPC code: B01J19/10


 

Indian Journal of Pure & Applied Physics

Vol. 43, October 2005, pp. 759-764

 

 

 

 

 

Analysis of inverted type high pressure equations of state for solids

 

S Digpratap, K Sushil & B P Singh

Department of Physics, Institute of Basic Sciences, Khandari, Agra 282 002 (UP) India

E-mail: bhanuprakashsingh@yahoo.co.in

Received 7 March 2005; revised 7 June 2005; accepted 14 July 2005

Diffrent inverted type equations of state (EOS) have been discussed, which express volume ratio as a function of pressure for materials at a given temperature. It is shown in the present study that some of these EOS do not satisfy the basic requirements revealed from the fundamental thermodynamics for solids in the limit of extreme compressions developed by Stacey. The critical test of EOS for solids under extreme compressions by evaluating the pressure-volume derivative properties viz. isothermal bulk modulus and its pressure derivative calculated for MgO and NaCl up to extremely large pressures has been presented. Among the five equations of state studied here, the inverted type of EOS due to Bose-Roy S and Bose-Roy P has been found to be most satisfactory. A detailed comparison of this EOS has been presented with the Keane’s EOS and the Stacey EOS.

Keywords: Inverted type equation of state, Bulk modulus, MgO, NaCl, Isothermal bulk modulus

 

 

Indian Journal of Pure & Applied Physics

Vol. 43, October 2005, pp. 765-771

 

 

 

 

Growth mechanism of carbon nanotubes deposited by electrochemical technique

 

S K Mandal, S Hussain & A K Pal*

Department of Instrumentation Science, Jadavpur University, Calcutta 700 032

Received 25 July 2005; accepted 25 August 2005

Understanding the nucleation and growth of carbon nanotubes at room temperature by a novel electrochemical process using acetonitrile as the electrolyte is investigated here. Microscopic insight into the nucleation process clearly reveals coalescence of amorphous carbon clusters in a branched network instigated mainly by dangling-bond induced relaxation and subsequent rearrangement of carbon atoms through a quasi-liquid state leading to the formation of multi-walled carbon nanotubes. Such a direct conversion of amorphous carbon into nanotubes is not abrupt, rather driven by a slow thermodynamical process that is inherent to the electrochemical process.

Keywords: Carbon nanotubes, Growth, Electrodeposition

IPC Code: C25,B82B

 


 

Indian Journal of Pure & Applied Physics

Vol. 43, October 2005, pp. 772-776

 

 

 

 

Theoretical study of ABO3 type perovskite with reference to KNbO3

Kuldeep Singh, S C Bhatt & B S Semwal

Dielectric and Ultrasonic Laboratory, Department of Physics, H N B Garhwal University,

Srinagar Garhwal 246 174

Received 2 April 2004; revised 28 June 2005; accepted 4 July 2005

One-dimensional model study has been carried out for KNbO3 system by the model Hamiltonian proposed by B D Silverman. Third and fourth order coupling constants, change in coupling constants by doping, spring constants, shift and width have been calculated and the variation of polarization mode frequency and polarization per unit electric field with temperature (T) has been obtained for KNbO3 system. The values obtained are also compared with the values obtained by the Hamiltonian proposed by Pytte.

Keywords: Perovskite, Polarization, Shift and width, Spring constants

Indian Journal of Pure & Applied Physics

Vol. 43, October 2005, pp. 777-782

 

 

 

 

Dielectric dispersion and microwave dielectric study of marbles
in support of radar investigations

 

R J Sengwa* & A Soni

Microwave Research Laboratory, Department of Physics, J N V University, Jodhpur 342 005, Rajasthan

Recevied 13 February 2004; revised 11 August 2005; accepted 16 August 2005

The dielectric permittivity e¢ and loss e¢¢ of nine marble samples collected from open marble mines of Makarana, Rajsamand, Ambhaji and Kesariyaji of Rajasthan were studied in the frequency range 100 Hz-100 kHz and also at 10.1 GHz at room temperature. It is found that the e¢ values of dry marbles decrease with increase in frequency in the range 100 Hz-100 kHz. All the studied marbles are governed by the Cole-Cole dielectric dispersion. The values of static dielectric constant eo, high frequency limiting dielectric constant e¥, dielectric relaxation strength De, distribution parameter a, and relaxation time for dipole rotation t were determined from the complex Cole-Cole plots. All these samples have a values greater than 0.5 and their De values vary significantly. Further, wide variation in ac conductivity s is also observed for different samples. The effect of sample bulk density and variation in the chemical composition on low frequency and microwave permittivity of the studied marbles have been recognized. The measured values of dielectric permittivity of these marbles were also compared and discussed with the earlier reported e¢ values of marbles and limestones of other regions. The precise microwave dielectric measurements of marbles and recognization of their dependence on petrological and chemical composition are interesting and can be used in support of radar investigations of the Earth’s geology.

Keywords: Geological materials, Marbles, Dielectric constant, Cole-Cole plots, Relaxation time

IPC code: G01R27/26


 

Indian Journal of Pure & Applied Physics

Vol. 43, October 2005, pp. 783-786

 

 

 

 

Segregation behaviour of trace metal impurities during ultra high
purification of gallium by zone refining

 

U Rambabu*, N R Munirathnam, R C Reddy & T L Prakash

Centre for Materials for Electronics Technology (C-MET), High Purity Materials Division, IDA Phase II,
Cherlapally, HCL (Post), Hyderabad 500 051

Received 15 June 2005; accepted 12 August 2005

The details of an in-house fabricated laboratory scale horizontal zone-refiner (HZR) for the purification of indigenous 4N (99.99%) gallium have been reported. The purified gallium ingot was analyzed for its selected trace metal impurity elements, namely Zn, Pb, Cu, Al, Cr, Ni, Fe, B and Mn using inductively coupled plasma optical emission spectrophotometer (ICP-OES). Segregation behaviour of the trace metal impurities throughout the ingot have been illustrated. The repeated experimental results confirm 6N (99.9999%) purity gallium.

Keywords: Electronic materials; High purity gallium; Zone refining; Trace metal impurities; ICP-OES analysis

IPC Code: B28D5/00

Indian Journal of Pure & Applied Physic

Vol. 43, October 2005, pp. 787-793

 

 

 

 

Study of impedance spectroscopy conducting polymer prepared with the use of water soluble support polymer

 

D K Ray*, A K Himanshu# & T P Sinha+

+Department of Physics, Bose Institute, Kolkata 700 009

*Department of Radiotherapy, Chitranjan National Cancer Institute, Kolkata 700 026

#School of Studies in Physics, Jiwaji University, Gwalior 474 011

Received 28 March 2005; accepted 8 August 2005

The intrinsically conducting polymer (ICP), polyaniline (PANI) is synthesized by chemical oxidative polymerization process with the help of water soluble support polymer poly-vinyl alcohol (PVA). The field dependence of the dielectric response is measured in the frequency range 50 Hz-1 MHz and temperature range 140-318 K. The frequency dependence of the imaginary impedance (Z²) is found to obey an Arrhenius law with the activation energy of 0.0176 eV. An analysis of real and imaginary parts of dielectric permittivity, conductivity formalism and impedance (Z) with frequency and temperature is performed, showing the polydispersive nature of the sample as confirmed by Cole-Cole plot as well as the scaling behaviour of the Z². The frequency dependent electrical data are discussed in the context of models for dc and ac transport in PANI-PVA composite, with the results supporting hopping of charges among positively charged polaron and bipolaron states. These results elucidate that there is an increased coupling among the local dipolar motions (short-range order localized motion).

Keywords: Conducting polymer, Polyaniline-polyvinyl alcohol, Impedance spectroscopy, Dipolar motions

IPC Code: G01J3/00,C08F118/00

Indian Journal of Pure & Applied Physics

Vol. 43, October 2005, pp. 794-798

 

 

 

 

Effect of charge bump on the series resistance and microwave properties of
Si n+np+ IMPATT diode at X-band

 

P De

Department of Physics, Gobardanga Hindu College, P O Khantura, 24 PGS(N), 743273, West Bengal

Received 24 January 2005; accepted 21 June 2005

The value of series resistance (Rs) of Si n+np+ IMPATT diode has been studied through computer simulation considering experimental bias current and frequency in the X-band, and the results fit well with the device data (1.6 W at 10 GHz) for the flat doping profile. It is further observed that the value of Rs decreases from 1.76 to 0.1128 W at 10.7 GHz under experimental current density (3.45´106 A.m-2) and temperature (373K), as the doping profile changes from flat to low-high-low(lhl) type with the incorporation of charge bump. The electric field and the negative resistivity profiles in the depletion layer clearly indicate the advantage of lhl doping profile on the series resistance as well as on its microwave properties. The analysis also gives an idea on the unison of load conductance of the waveguide and negative conductance of the diode at resonance.

Keywords: Series Resistance, Low-high-low, SDR, X-band, IMPATT diode

IPC Code: H01L29/861

Indian Journal of Pure & Applied Physics

Vol. 43, October 2005, pp. 799-805

 

 

 

 

Realization of voltage-mode and current-mode biquad filters using current feedback amplifiers

N A Shah, M F Rather & S Z Iqbal

Department of Electronics & Instrumentation Technology, University of Kashmir, Srinagar 190 006

Email: farsgr@yahoo.co.in

Received 21 October 2004; revised 28 March 2005; accepted 11 July 2005

This paper presents two each of voltage-mode (VM) and current-mode (CM) universal biquad filtering topologies constructed around current feedback amplifier (CFA). The VM configurations are based on lossless integrator loops. One of the CM topologies has three inputs and one output and the other with a single input and three outputs. Both the VM configurations and one of the CM circuits realize lowpass notch (LPN) and highpass notch (HPN) functions in addition to all the generic filtering functions while the other CM circuit realize three basic filtering functions simultaneously. The filter parameters are orthogonally adjustable and enjoy low sensitivity figures. The circuits have been simulated using personal computer simulation program with integrated circuit emphasis (PSPICE) and simulation results are found to be in conformity with the theoretical values.

Keywords: Active filters, Voltage/current-mode circuits, Current feedback amplifiers, Biquad filters

IPC Code: H03H