Indian Journal of Pure and Applied Physics
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VOLUME 39
54
NUMBER 12
DECEMBER 2001
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CONTENTS
Nuclear Physics
Uranium, radium and radon exhalation studies in some soil samples from Una district,
Himachal Pradesh, India using track etching technique
761
Ajay Kumar, Baldev Singh & Surinder Singh*
Atomic and Molecular Physics
Detection of rotational lines of NaSH molecule
765
Arvind Kumar Sharma* & Suresh Chandra
Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics and Fluid Dynamics
Self-focusing of a Gaussian laser beam in parabolic profile optical fibre having Kerr non-linearity
768
R K Khanna* & A K Nagar
Refractive indices of binary liquid mixtures of squalane with benzene, cyclohexane and hexane
776
at 298.15 to 313.15 K
Subhash C Bhatia*, Neelima Tripathi & Gyan P Dubey
Sound attenuation in BaxSr1-x TiO3 perovskites
781
Ashok Kumar*, U C Naithani & B S Semwal
Critical behaviour of complex fluids and supra-molecular length scale
789
A Kumar
Condensed Matter: Structure, Mechanical and Thermal Properties
Microhardness and X-ray diffraction studies on polymer blends of poly(ethylmethacrylate)
(PEMA) and poly(ethylene oxide) (PEO): Plasticization and crystallization aspects
795
S K Awasthi & R Bajpai*
Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Microwave dielectric measurements in different varieties of rapeseed-mustard seeds in powder form
799
A K Bansal*, P J Singh & K S Sharma
Electro-optical studies in chemically deposited Sm/Pr doped (Cd-Pb) S films
804
M Mukherjee, P Bose & S Bhushan*
ESR-A technique exclusive for understanding semiconductor processes
810
C S Sunandana
Interdisciplinary Physics and Related Areas of Science and Technology
Measurement of mass and linear attenuation coefficients of gamma-rays for various elements through
816
aqueous solution of salts
M T Teli*, C S Mahajan & R Nathuram
Bioluminescence of fireflies and evaluation of firefly pulses in light of oscillatory chemical reactions
825
J Saikia, R Changmai & G D Baruah*
Spectral and normal coordinate analysis of 5,6-diamino uracil
829
V Krishnakumar* & R Ramasamy
833
Index
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*The corresponding author has been indicated by (*) mark in case of papers with more than one author
2
INDIAN J PURE & APPL PHYS, VOL 38, NOVEMBER 2000
Indian Journal of Pure & Applied Physics
Vol. 39, September 2001, pp. 761-764
Uranium, radium and radon exhalation studies in some
soil samples from Una district, Himachal Pradesh, India
using track etching technique
Ajay Kumar, Baldev Singh & Surinder Singh
LR-115 plastic track detectors have been used for the measurement of radon exhalation rate and radium concentration
in soil samples collected from some villages of Una District, Himachal Pradesh, India. Uranium concentration has also been
determined in these samples using ‘Fission Track Technique’. Uranium concentration in soil samples has been found to
vary from 1.07 to 2.47 ppm whereas radium concentration varies from 3.10 to 12.41 Bq/kg. The radon exhalation rate in
these samples varies from 126.19 to 506.76 mBqm-2hr-1 (3.81 to 15.24 mBqkg-1hr-1). A good correlation has been observed
between radon exhalation rate and uranium concentration in the soil samples.
Indian Journal of Pure & Applied Physics
Vol. 39, December 2001, pp. 765-767
Detection of rotational lines of NaSH molecule
Arvind K Sharma & Suresh Chandra
Laboratory detection of NaSH molecule in absorption has been reported by Kagi & Kawaguchi, Astrophys J, 491
(1997) L129. They observed only a-type rotational transitions of the molecule. The reason for not observing b-type
rotational transitions was assigned to a small value of b-component of electric dipole moment (b = 0.63 D) as compared to
a-component of electric dipole moment (a = 8.91 D) of the molecule. The b-type transitions may be detected in emission
in interstellar medium having low densities. However, it is not feasible to detect b-type rotational transitions in the
absorption spectrum.
Indian Journal of Pure & Applied Physics
Vol. 39, December 2001, pp. 768-775
Self-focusing of a Gaussian laser beam in parabolic profile optical
fiber having Kerr non-linearity
R K Khanna and A K Nagar
A steady state analysis of self-focusing of Gaussian laser beam propagating in a parabolic index profile silica fiber of
cylindrical core has been presented. The Kerr non-linearity acts as perturbation on the geometrically built-in radial
inhomogeneity of the dielectric fiber. A paraxial ray approach has been adopted following Akhmanov and Sodha using
WKB approximation. The beam-width parameter at different axial points is studied by varying different parameters. An
appreciable decrease in critical beam power for focusing has been reported. It has been found that when the beam power
attains this threshold value, the beam propagates in a self-trapped waveguide mode. Above the threshold, the beam gets
self-focused when the non-linear effect dominates over the diffraction effect. Below this threshold the beam diverges out
forming a diverging lens. The beam intensity at the focusing points has been calculated for the fiber for different media and
fiber lasers. The propagation characteristics of laser beam are found to be very sensitive with respect to the delta parameter
of the fiber and the self-focusing length is found to decrease with the increase in incident beam power. Results indicate the
possibility of a new kind of passive non-linear optical device for manipulating output light intensity.
Indian Journal of Pure & Applied Physics
Vol. 39, December 2001, pp. 776-780
Refractive indices of binary liquid mixtures of squalane with benzene,
cyclohexane and hexane at 298.15 to 313.15 K
Subhash C Bhatia, Neelima Tripathi & Gyan P Dubey
Densities, , at 298.15 K and refractive indices, n, at 298.15, 303.15, 308.15 and 313.15 K have been measured for the
binary liquid mixtures of squalane with benzene, cyclohexane and hexane over the whole mole fraction range. From
refractive index data, the refractive index deviations, n, at different temperatures have been calculated and fitted to the
Redlich-Kister polynomial equation to estimate the adjustable parameters and the standard deviations. Further, theoretical
prediction of refractive indices of these binary liquid mixtures at 298.15 K have been made using various mixing rules.
Results obtained have been discussed in terms of average percentage deviations.
Indian Journal of Pure & Applied Physics
Vol. 39, December 2001, pp. 781-788
Sound attenuation in BaxSr1-xTiO3 perovskites
Ashok Kumar, U C Naithani & B S Semwal
An expression is obtained for the sound attenuation constant in anharmonic Ba xSr1-xTiO3 ferroelectric crystal, using
double-time temperature dependent Green’s function technique. The mass and force constant changes due to impurity
atoms, are taken into account in the Silverman-Joseph Hamiltonian augmented with higher order anharmonic terms. The
defect and anharmonic contributions to the attenuation constant are discussed separately. An anomalous increase in
attenuation constant is predicted in the vicinity of Curie temperature. The soft mode is held responsible for this effect. The
effect of defect and anharmonicity on stabilization of the soft mode frequency is also studied. With addition of defect
(concentration x) in BaxSr1-xTiO3, the soft mode frequency continuously decreases and hence the attenuation constant ()
increases. The results agree with those obtained by Tani & Tsuda, J Phys Soc Japan, 26 (1969) 113 and Heuter & Neuhaus,
J Acoust Soc Am, 27 (1955) 292.
Indian Journal of Pure & Applied Physics
Vol. 39, December 2001, pp. 789-794
Critical behaviour of complex fluids
and supramolecular length scale
A Kumar
A few aspects of complex fluids (electrolyte solutions, polymer solutions, amphiphilic systems, etc.) from the
perspective of critical behaviour normally observed in non-interacting, neutral fluids have been presented. A recurring
theme in complex fluids is the structuring of these systems and the associated supramolecular (mesoscopic) length scale.
The authors adduce evidence to support the claim that, intriguing and poorly understood features emerge in electrolyte
solutions and the dilute suspensions of charge-stabilized colloids in liquid solutions. These results are based on
investigations near to and away from liquid-liquid critical point using laser light scattering, turbidity, small-angle X-ray
scattering (SAXS), visual observations and the excess molar volume measurements.
Indian Journal of Pure & Applied Physics
Vol. 39, December 2001, pp. 795-798
Microhardness and X-ray diffraction studies on polymer blends of
poly (ethylmethacrylate) (PEMA) and poly (ethylene oxide) (PEO):
Plasticization and crystallization aspects
S K Awasthi & R Bajpai
3
4
INDIAN J PURE & APPL PHYS, VOL 38, NOVEMBER 2000
Polymer blends of poly (ethylmethacrylate) (PEMA) and poly (ethylene oxide) (PEO) with different weight percentage
ratios of the two polymers have been prepared using solution cast technique. PEMA as non-crystallizable and PEO as
crystallizable polymer when blended yield interesting features regarding plasticization and crystallinity aspects. The
microhardness and X-ray diffraction studies have been utilized respectively to detect the plasticization and crystallinity in
PEMA:PEO polyblend. The decrease in the value of surface microhardness with increasing content of PEO in the blend
reveals plasticization effect. The increase in crystallinity of polymer blends with increasing content of PEO is observed by
X-ray diffraction. Thus PEO crystallizes in amorphous PEMA.
Indian Journal of Pure & Applied Physics
Vol. 39, December 2001, pp. 799-803
Microwave dielectric measurements in different varieties of
rapeseed-mustard seeds in powder form
A K Bansal, P J Singh & K S Sharma
Effect of packing density on dielectric parameters, relaxation time and conductivity of three different varieties of
rapeseed-mustard seeds in the form of powders has been studied at x-band (8.93 GHz) microwave frequency. Experimental
results on powders of different relative packing fractions (r) have been used to obtain transformation to 100% solid bulk
using correlation formulae of Landau-Lifshitz-Looyenga and Böttcher. In case of seed grains like rapeseed-mustard where
it is not possible to define solid bulk exactly, the authors have assumed the finest crushed closely packed assembly of the
seed grains as solid bulk for the comparison of these correlation formulae between powder and solid bulk. This assumption
works well as there is fair agreement between the calculated values of dielectric parameters and the values obtained
experimentally for solid bulk. Appreciable agreement between the experimentally obtained values and the theoretical values
obtained by Böttcher's and Landau-Lifshitz-Looyenga's formulae shows large cohesion in the particles of rapeseed-mustard
powders under investigation, serving as a continuous medium.
Indian Journal of Pure & Applied Physics
Vol. 39, December 2001, pp. 804-809
Electro-optical studies in chemically deposited Sm/Pr doped
(Cd–Pb) S films
M Mukherjee, P Bose & S Bhushan
Results of photoconductivity, optical absorption, XRD & SEM studies have been presented for different (Cd–Pb)S
films. From the photo-current curves IPC/IDC ratio of the order of 105 is observed for undoped (Cd0.95-P0.05)S film which
improves to 106 for the systems prepared with NaF and Samarium/Praseodymium nitrate. Due to annealing of the films at
400 C, dark current decreases to almost zero value along with a decrease in photo-current also but the ratio goes to very
high value. From the analysis of decay curves, lifetime of the carriers, mobility and trap-depths are determined. The values
of lifetime and mobility are found to increase in presence of impurities. Band-gaps determined from optical absorption and
photoconductivity excitation spectral studies show a similar nature in presence of impurities. The direct band-gap is found
for mixed films. XRD studies show crystalline nature and according to SEM studies layered growth of films takes place.
Indian Journal of Pure & Applied Physics
Vol. 39, December 2001, pp. 810-815
ESR-A technique exclusive for understanding
semiconductor processes
C S Sunandana
ESR has recently emerged as an exclusive technique for the study of processes in semiconductor materials and devices.
Four cases namely H in Si, O-related centers in porous Si, VLSI failure analysis and localized electrons and holes in aSi3N4 have been discussed, in an attempt to demonstrate the power of the technique. Some problems for the future are
indicated.
Indian Journal of Pure & Applied Physics
Vol. 39, December 2001, pp. 816-824
Measurement of mass and linear attenuation coefficients of gammarays for various elements through aqueous solution of salts
M T Teli, C S Mahajan & R Nathuram
Solution technique is developed for the measurement of linear and mass attenuation coefficients of salts for gammarays and from them elemental attenuation coefficients are estimated. Improved mixture rule (Radiat Phys & Chem, 53
(1998) 593), is employed for the measurement for salts containing carbonates, sulphates and chlorides etc. for various
Gamma energies Mass attenuation coefficients for many elements are estimated. Their results show excellent agreement
with theory.
Indian Journal of Pure & Applied Physics
Vol. 39, December 2001, pp. 825-828
Bioluminescence of fireflies and evaluation of firefly pulses in light of
oscillatory chemical reactions*
J Saikia, R Changmai & G D Baruah
The bioluminescence spectra of few species fireflies [species: Photinus pyralis, coleoptera: Lampyridae: Phengodes
lacticollis, lampryridae and Photuris pennsylvanica, Lampyridae] have been photographed in the wavelength range 5000 –
6700 Å. The intensity distributions of the spectra have been investigated. The scanning of the individual firefly pulses have
been recorded and it is shown that the intensity pattern of the pulses exhibit the oscillatory behaviour in chemical reaction
inside the metabolism of firefly. The nature of relaxation oscillation is also examined in the firefly emission.
Indian Journal of Pure & Applied Physics
Vol. 39, December 2001, pp. 829-832
Spectral and normal coordinate analysis of 5,6-diamino uracil
V Krishnakumar & R Ramasamy
The FTIR spectrum of 5,6-diamino uracil has been recorded in the region 4000-100 cm-1 and the normal coordinate
analysis has been carried out by assuring a CS point group symmetry. All the normal modes of vibrations are assigned and
calculations on the potential energy distribution are performed.
Indian Journal of Pure & Applied Physics
Vol. 39, December 2001, pp. 833-855
Index
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