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Indian Journal of Pure and Applied Physics
___________________________________________________________________________________
VOLUME 40
NUMBER 6
JUNE 2002
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CONTENTS
Atomic and Molecular Physics
Vibrational analysis of 2-chloroheptane
Neena Jaggi & RM P Jaiswal
Thomas-Fermi calculations for atoms in high magnetic field using realistic model
O H Mobarek* & E Al-Laheani
385
393
Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics and Fluid Dynamics
Ultrasonic pulse-broadening and attenuation in volcanic rock-A case study
M V M S Rao*, L P Sarma & K J Prasanna Lakshmi
396
Condensed Matter: Structure, Mechanical and Thermal Properties
Pair-breaking effects on charge imbalance in superconductors
B A Mattoo
Semimetal-semiconductor transition in Bi-In System
Sanjeeta Rani* & G K Chadha
Computation of thermodynamic functions of 2-and 4-phenylpyridine from vibrational spectra
M Isaq*, Sanjiv Arora & R S Kajal
402
407
417
Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Scattering characteristics of small particles in resonance region: Effect of shape
J J Joshi, H S Shah*, S K Sharma & RV Mehta
Dielectric relaxation in ternary mixtures of benzotrifluorides
G D Rewar & D Bhatnagar*
Temperature and frequency dependent dielectric constant/loss studies in pristine and high temperature
annealed poly (p-phenylene sulphide)
J K Quamara, N Singh & Azad Singh*
421
430
436
Interdisciplinary Physics and Related Areas of Science and Technology
Effective atomic number studies in different body tissues and amino acids
K Singh* & Gagandeep
442
News Scan
Fibre-optic telecommunications
J B Dhawan
450
Addendum
452
____________
*The corresponding author has been indicated by (*) mark in case of papers with more than one author
Indian Journal of Pure & Applied Physics
Vol. 40, June 2002, pp. 385-392
Vibrational analysis of 2-chloroheptane
*Neena Jaggi & R M P Jaiswal
Infrared and Raman spectra of 2-chloroheptane were recorded at ambient temperatures as pure liquid. Fundamental
frequencies of 2-chloroheptane have been identified by carrying out the analysis of these spectra. Normal coordinate
calculations have been made for the five probable conformations of the molecule by transferring force-constants from the
studies of 2-chlorohexane. All the observed frequencies in the spectra could be assigned to the five conformations within an
average frequency error 6.4 cm-1.
Indian Journal of Pure & Applied Physics
Vol. 40, June 2002, pp. 393-395
Thomas-Fermi calculations for atoms in high magnetic field
using realistic model
O H Mobarek & E Al-Laheani
An approximate solution of the Thomas-Fermi equation for positive ions in a high magnetic field is obtained by making use
of the variational principle. The radial wavefunctions of the hydrogen-like atom are used as the trial function that contains
some variational parameters and satisfies the appropriate boundary and the normalization conditions. These parameters are
determined by extemalizing the variational expression with respect to the parameters. These parameter values are then used
to obtain the desired physical quantities. The initial slope of the variational trial function for several ions is obtained from
which the energy and the ionization energy can be found. The results of the present calculation are in good agreement with
those available in literature.
Indian J Pure & Applied Physics
Vol. 40, June 2002, pp. 396-401
Ultrasonic pulse-broadening and attenuation in
volcanic rock - A case study
M V M S Rao, L P Sarma & K J Prasanna Lakshmi
Ultrasonic pulse-broadening measurements at 1.0 MHz frequency have been carried out at the ambient conditions in a set of
volcanic rocks of south-east Gujarat. The experimental data have been processed along with the results of P-wave velocity
(Vp) measurements leading to the determination of internal friction (Qp-1) and attenuation (p). The attenuation in rhyolites
is relatively high (average Qp-1 = 0.0051, p = 0.0330 dB/cm) compared to basalts (average Qp-1 = 0.0019, p = 0.0100
dB/cm) which are fine-grained and well crystallized. The mineral composition, in particular, the volume percentage of
ground mass in rhyolites is found to have a strong control on both the attenuation and velocity of the rock samples tested.
The experimental method is briefly described and the results obtained are presented and discussed.
Indian Journal of Pure & Applied Physics
Vol. 40, June 2002, pp. 402-406
Pair-breaking effects on charge imbalance in superconductors
B A Mattoo
Using quasi-classical Green function, a general formalism for calculating charge imbalance and its relaxation in nonequilibrium superconductors is presented. The formalism is applicable at arbitrary temperatures, under conditions when the
width of quasi-particle state is appreciable due to pair breaking processes and when strong-coupling effects are significant.
In the limit of small pair-breaking and for a weak coupling superconductor the collision term in the formalism reduces to
the one in the quasi-particle Boltzmann equation.
Indian Journal of Pure & Applied Physics
Vol. 40, June 2002, pp. 407-416
Semimetal-semiconductor transition in Bi-In system
Sanjeeta Rani &G K Chadha
Department of Physics and Astrophysics, Delhi University, New Delhi 110 007
Received 25 February 2002; accepted 18 April 2002
Semimetal-semiconductor transition in Bi-doped with 4 at. % In single crystal is reported for the first time. Resistivity and
Hall coefficient measurements performed on single crystalline sample of Bi-In (4at.%) system for an extensive range of
temperature from 4.2-300 K, reveal semiconducting behaviour explicitly in the range 30-130 K. Electronic parameters, i.e.
carrier concentration and Hall mobility are calculated for the entire temperature range of 4.2-300 K. The pair of light mass
bands at LC and Lv moves up relative to the TV band resulting in the disappearance of the overlap between the LC band and
the TV band and an energy gap of the order of 37.3 MeV is introduced between the light electron (LC) and heavy hole (TV)
band. Further, the direct band gap between Lc and Lv bands is narrowed to a value of 10.9 MeV in comparison to pure
bismuth. An impurity level is also reported on account of doping corresponding to activation energy of 4.1 MeV. Results
from microhardness measurements and XRD studies of pure Bi and Bi-In (4 at. %) alloy reveal that In makes complete
solid solution with Bi and gains effective entry into the lattice, altering the periodicity of Bloch Potential and modifying the
band structure of Bi. This seems to be the reason that the transition from semimetal to semiconductor takes place in the BiIn alloy.
Indian Journal of Pure & Applied Physics
Vol. 40, June 2002, pp. 417-420
Computation of thermodynamic functions of 2- and
4-phenylpyridine from vibrational spectra
M Isaq*, Sanjiv Arora† & R S Kajal**
The complete assignments of the observed frequencies are used to compute the thermodynamic functions, namely, the
entropy, heat capacity, enthalpy and the free energy of 2- and 4-phenylpyridine. These functions have been calculated by
using standard expressions, at one atmospheric pressure in the temperature range 100-1500 K under the rigid rotator
harmonic oscillator approximation.
Indian Journal of Pure & Applied Physics
Vol. 40, June 2002, pp. 421-429
Scattering characteristics of small particles in resonance region:
Effect of shape
1
J J Joshi , H S Shah2, S K Sharma3 & R V Mehta4
Scattering characteristics of spherical and nonspherical particles are studied using T-matrix method. Particle size is varied
up to radius r = 0.3 micron. Computations are made for two chromatic pigments namely red and green with aspect ratio
varying from 1 to 6 for three wavelengths  = 440, 560 and 680 nm used in colour calculations. Results show that the effect
of shape is predominant on scattering characteristics of particles in resonance region. Scattering parameters are used to
calculate reflectance of pigment system using many-flux multiple scattering theory. Results show that deviations in pigment
shape from sphericity have remarkable effect on reflectance and hence on colour exhibited by pigment dispersions.
Indian Journal of Pure & Applied Physics
Vol. 40, June 2002, pp. 430-435
Dielectric relaxation in ternary mixtures of benzotrifluorides
G D Rewar & D Bhatnagar
Dielectric relaxation in four ternary systems of benzotrifluorides consisting of benzotrifluoride, 2-chloro-benzotrifluoride
and 2-amino-benzotrifluoride has been studied at 9.408 GHz over a temperature range 290-330 K. Static dielectric constant
and refractive index of individual components of these benzotrifluorides and their mixture compositions have been
measured. The measured dielectric data of these benzotrifluorides have been discussed in terms of distribution of relaxation
time and its variation with temperature. The process of dipole orientation and viscous flow in these liquids has been
discussed on the basis of rate theory. Various thermodynamical parameters viz. entropy, enthalpy and free energy of
activation have been determined using measured dielectric data. These calculated thermo dynamical parameters for
relaxation processes and viscous flow processes confirm existence of both inter-molecular and intra-molecular orientations
in these substituted benzotrifluorides. These polar compounds under investigation have been used in pure form as dielectric
samples. The methods used to obtain results presented in this paper are based on the measurement of standing wave pattern
in a dielectric medium.
Indian Journal of Pure & Applied Physics
Vol. 40, June 2002, pp. 436-441
Temperature and frequency dependent dielectric constant/loss studies
in pristine and high temperature annealed poly (p-phenylene sulphide)
J K Quamara, N Singh1 & Azad Singh
Temperature and frequency dependent dielectric behaviour has been investigated for pristine and high temperature annealed
poly p-phenylene sulphide (PPS) in the temperature range 30 to 250 C at frequencies 120 Hz, 1, 10 and 100 kHz. Samples
used were in the form of pellets. A continuous decrease in dielectric constant from 30 to 140 C is according to Kirkwood
model. A dipolar relaxation process (-relaxation) associated with the newly formed cross-linked structure due to
annealing and rigid amorphous phase (RAP) dipolar relaxation (-relaxation) have been held responsible to dominate the
dielectric behaviour in the temperature region 140 to 190 C and making  temperature independent in this temperature
region. A dielectric loss maxima observed between 140 to 160 C confirms -relaxation. Above 190 C, the crystallineamorphous region with RAP as interface material leading to interfacial polarization (-relaxation) has been held
responsible for increasing the  value with temperature. The -relaxation is confirmed through a dielectric loss peak in T curve around 230 C. The frequency dependent nature of the -loss peak shows its distributive nature in relaxation time.
A decrease in the - and -loss peak magnitudes in high temperature annealed samples is due to increase in crystallinity.
Indian Journal of Pure & Applied Physics
Vol. 40, June 2002, pp. 442-449
Effective atomic number studies in different body tissues
and amino acids
K Singh* & Gagandeep
Effective atomic numbers (Zeff) of body tissues and amino acids have been calculated theoretically over a wide energy range
from 10-3 to 105 MeV. The significant variations in Zeff due to composition of the material and domination of different
interaction processes in different energy regions were observed.
Indian Journal of Pure & Applied Physics
Vol. 40, June 2002, pp. 450-451
News Scan
Fibre-optic telecommunications
Scientists engaged in R&D research are now underway to give birth to photonic crystal lasers, light-emitting diodes
(LEDs), and photonic crystal thin films to serve as anti-counterfeit protection on credit cards. Ultimately, researchers hope
to build diodes and transistors from this novel material that will one day enable the construction of an all-optical computer.
It is possible to create energy levels in the photonic bandgap by introducing defects. For example, changing the size of a
few of the holes in a photonic crystal is "equivalent to breaking the perfect periodicity of the silicon-crystal lattice", says
Greg Parker, a professor of photonics at Southampton University in England. (Parker & Charlton, Physics World, (2000),
p. 129). Thus, although perfect crystals are valuable for fabricating dispersive elements such as superprisms and threedimensional (3-D) mirrors, those with defects enable researchers to custom- design photonic crystals that allow precise
control of the frequencies and directions of propagating electromagnetic waves. This feature makes them especially useful
in optical telecommunications and as laser sources. In this sense, the huge optical telecommunication market is close to reap
the benefits of photonic crystals research.