006658   Javidan K;Sarbishaei M (Department of Physics, Ferdowsi University of Mashhad, Iran, ) : Sine-gordon solitons in a nontrivial metric. Indian J Phys-Pt B 2001, 75(5), 413-18.

Studies the behavior of soliton solutions of the sine-Gordon equation with a nontrivial metric. The impurity interactions of a soliton by looking at the impurity as a nontrivial medium in which the soliton propagates. Therefore, add a potential-like term v(x) to the metric. Numerical simultations show that with the presence of a small potential-like v(x) in the metric, the conserved quantities of system of solitons, like topological charge and total energy remain unchanged. Studies the evolution of soliton in some cases where v(x) is a well or a barrier. The soliton behaves like a particle in most of the cases.

15 illus, 12 ref

006657   Hota P K;Vijayan V;Singh L P (Medical Physics Unit, AH Regional Cancer Centre, , Cuttack-753 007) : Application of X-ray spectroscopic analysis to human blood samples. Indian J Phys-Pt B 2001, 75(4), 333-6.

X-ray emission techniques like Particle Induced X-ray emission (PIXE) and Energy Dispersive X-ray Fluorescence (EDXRF) spectrometry are applied to analyse the elements in biomedical samples at the Institute of Physics, Bhubaneswar in collaboration with the Acharya Harihara Regional Cancer Centre, Cuttack. After the development of the systems, initially experiments were carred out with the certified reference materials (CRMs) like IAEA animal blood standards to verify their applicability to biomedical samples. Then human blood samples from different patients as well as healthy persons were analysed to compare the results applying both the techniques. Both the X-ray emission techniques are discussed in detail with their advantages and limitations. The results obtained by both the methods prove their efficiency for analysis of biomedical samples.

2 illus, 2 tables, 8 ref

006656   Hazarika S;Rai S (Department of Physics, J.B. College, Jorhat-785 001) : Optical properties of Nd3+ ions in alkali-alumino-borate glasses. Indian J Phys-Pt A 2001, 75(6), 629-32.

Optical absorption and emission intensities are investigated for trivalent Nd ions in alkali-alumino-borate glasses. Their absorption spectra have been measured in the region 400-800 nm. Oscillator strengths for transition between J-manifolds were calculated using the Judd-Ofelt intensity parameters (Ωλ). Using these parameters and calculated matrix element (U^λ), radiative transition probability, branching ratio and emission cross section for stimulated emission were calculated for ⁴F3/2 → ⁴I9/2 transition. The phenomenological parameters are used to predict the laser properties of neodymium ion in alkali-alumino-borate glasses.

2 illus, 2 tables, 21 ref

006655   Ghosh M;Chakraborti S;Misra T N (Department of Spectroscopy, Indian Association for the Cultivation of Science, Jadavpur, Calcutta-700 032) : Raman phonon spectroscopic study of solid state photoreaction in 7-bromo coumarin crystals. Indian J Phys-Pt B 2001, 75(4), 341-5.

Photodimerization reaction in 7-bromo coumarin (7BC) in the crystalline state has been studied by Raman phonon spectroscopy. Monotonic red shift of the phonon bands and nonappearance of any new phonon bands on reaction progress suggest that the mechanism is homogeneous and the reactant and the product form solid solution. Broadening of the phonon band suggests that the reaction lattice becomes disordered with the increase of product concentration. Significant overlap between the electronic absorption and emission bands indicates that the exiton-phonon coupling is not very strong in the monomer lattice. Softening of a specific phonon mode with the progress of reaction observed in the Raman spectrum suggests that the reaction is phonon mediated through this mode softening in the reaction, formation of cyclobutane ring through the <62>C=C<60> of the pyrone moiety is established by infrared and Raman spectroscopy.

5 illus, 15 ref

006654   Ghosh D;Deb A;Bandyopadhyay P;Mondal M; Bhattacharyya S;Ghosh J;Patra K (Nuclear and Particle Physics Research Centre, Department of Physics, Jadavpur University, Calcutta-700 032) : Evidence of multifractal structure of multiplicity distributions of pions produced in π-AgBr interaction at 350 GeV/c. Indian J Phys-Pt A 2001, 75(6), 669-71.

Analyses the experimental data on the bin size dependence of charged pion multi-particle distribution in π-AgBr interaction at 350 Gev/c following the method proposed by Takagi. Linear relation between <60>n In n<62>/<60>n<62> and In<60>n<62> and also between In<60>n^q<62> and In<60>n<62> for q = 2, 3, 4 and 5 has been observed in the multiplicity distribution of the (pseudo) rapidity space. Calculates the generalized dimensions Dq for q = 2, 3, 4 and 5 from the slope of linear-log behaviour. The results of study signify the multifractal structure.

3 illus, 13 ref

006653   Ghosh B;Chakrabarty S (Department of Physics, , Visva-Bharati, Santiniketan-731 235) : Renormalization-group-improved radiatively corrected Higgs masses in the minimal supersymmetric standard model at LEP2. Indian J Phys-Pt A 2001, 75(6), 651-6.

Applies the method of solving the renormalization group equations, for top quark and bottom quark Yukawa couplings in the two-Higgs doublet model given by Parida and Usmani to the above studies of Haber et al. The effects of the running vacuum expectation values (VEVs) in the two Higgs doublet model below μ = Msusy have also been taken into account in terms of solutions of RGEs for the VEVs v1 (μ) and v2(μ. It may be mentioned that at mass scales below Msusy, the solutions of the non-SUSY (Supersymetry) two Higgs doublet model are used. Interestingly, new results are obtained from systematic studies on the mass of lightest Higgs boson in MSSM which have importance in view of the LEP2 data and future LHC experiments.

8 illus, 10 ref

006652   Garraffo H M;Spande T F;Jain P;Kaneko T;Jones T H;Blum M S;Ali T M M;Snelling R R;Isbell L A;Robertson H G;Daly, J W (NIDDKD, Bioorganic Chemical Laboratory, , NIH, Bethesda, MD 20892, USA) : Ammonia chemical ionization tandem mass spectrometry in structural determination of alkaloids .II. Tetraponerines from Pseudomyrmecine ants. Rapid Commun Mass Spectrom 2001, 15(25), 1049-15.

Chemical ionization tandem mass spectrometry (CI-MS/MS) of alkaloids with ammonia reagent gas and collision-activated dissociation as well as EI-MS/MS were applied to the tetraponerine alkaloids in extracts from six pseudomyrmecine ants of the genus Tetraponera the MS/MS techniques along with gas chromatography Fourier transform infrared (GC/FTIR) spectra allowed identification in two extracts of seven of the eight known tetraponerines. The EI-MS/MS fragmentations proved diagnostic for the ring system and the CI-MS/MS patterns for the C-8 or C-9 substitution, while the Bohlmann bands in FTIR spectra were diagnostic for the C-8 or C-9 cinfigurations. An Indian ant (T. allaborans) had T-2, T-4 and T-8, while a Chinese ant (T. Binghami) had T-5, T-6, T-7 and T-8. Four other ants, T. rufonigra (India), T. penzigi (Africa), T. clypeata (Africa) and T. sp. of. emeryi (Africa), had no tetraponerines.

15 ref

006651   Ganapathy R;Kuriakose V C (Department of Physics, Cochin University of Science and Technology, Cochin-682 022) : Polarization modulational instability in a birefringent optical fiber with fourth order dispersion. Pramana J Phys 2001, 57(4), 743-54.

Obtains conditions for the occurrence of polarizaiton modulational instability in the anomalous and normal dispersion regimes for the coupled nonlinear Schrodinger equation modelling fourth order dispersion effects when the linearly polarized pump is oriented at arbitrary angles with respect to the slow and fast axes of the birefringent fiber.

8 illus, 19 ref

006650   Freeda T H;Mahadevan C (Department of Physics, S T Hindu College, Nagercoil-629 002) : Lattice variation and thermal parameters of gel grown KDP crystals added with some ammonium compounds. Pramana J Phys 2001, 57(4), 829-36.

Pure and impurity added (with NH₄Cl, NH₄NO₃, NH₄H₂PO₄, and (NH₄)₂SO₄) KDP single-crystals were grown by the gel method using silica gels. X-ray diffraction data were collected for powder samples and used for the estimation of lattice variation and thermal parameters like Debye-Waller factor, mean-square amplitude of vibration, Debye temperature and Debye frequency. The thermal parameters do not vary in a particular order with respect to impurity concentration. The results obtained are reported and discussed.

5 tables, 15 ref

006649   Dutta K;Sit S K;Acharyya S (Department of Physics, Raiganj College, Raiganj, Dist. Uttar Dinajpur-733 134) : Dielectric relaxation phenomena of rigid polar liquid molecules under giga hertz electric feild. Pramana J Phys 2001, 57(4), 775-93.

Dielectric relaxation phenomena of rigid polar liquid molecules chloral and ethyl-trichloroacetate (j) in benzene, n-hexane and n-heptane (i) under 4.2, 9.8 and 24.6 GHz electric fields at 30°C are studied to show the possible existence of double relaxation times t₂ t₁ for rotations of the whole and the flexible parts of molecules. The probability of showing double relaxation is more in aliphatic solvents indicating their nonrigidity. The probability of showing double relaxation is more in aliphatic solvents indicating their nonrigidity. The symmetric and asymmetric distribution parameters γ and δ are obtained from χ`<sub>ij</sub>/<99<sub>0ij</sub> and χ"<sub>ij</sub>/χ <sub>0ij</sub> at w<sub>j</sub> → 0 where χ`_ij and χ"_ij are real and imaginary parts of the complex orientational susceptibility χ^*_ij and χ_0ij is the low frequency susceptibility which is real. χ_ij's are involved with the measured dielectric relative permittivities ε`_ij, ε"_ij, ε_0ij and ε_∞ij of solutions.

6 illus, 4 tables, 28 ref

006648   Dutta H;Pradhan S K;De M (Department of Physics, The University of Burdwan, Golapbag, Burdwan-713 104) : Correlation between microstructure and mechanical property of industrial Cu-Mn-Zn alloys : effective of transitional solute Mn. Indian J Phys-Pt A 2001, 75(6), 607-14.

Eight compositions of Cu-Mn-Zn alloy α-phase and mixed phase (α-β) regions have been analysed both in the annealed and cold worked states employing Rietveld's power structure refinement method and Warren-Averbach's method of X-ray line profile analysis. The detailed microstructure has been analyzed in terms of several parameters depicting lattice imperfections like, stacking faults, particle size (coherently diffracting domain), r.m.s. strains dislocation densities, lattice parameter change etc. A specially prepared Si standard has been used in the Rietveld software for accurate estimation of instrumental broadening in the peak-broadening analysis. Grain size and shape, grain-boundary structures and several other metallographic features are obtained from optical microscopy studies. Vickers' microhardness values are measured and finally, different correlations amongst various parameters obtained from these studies are established. It is interesting to observe that the defect microstructures of the Cu-Zn-Mn alloys are primarily controlled by the presence of transitional solute Mn which precipitates continuously and discontinuously inside the grain, at the grain-boundary or in the form of dendritic networks.

8 illus, 17 ref

006647   Dhami A K;Dey T K (High Temperature Superconductivity Laboratory, Cryogenic Engineering C, Indian Institute of Technology, Kharagpur-721 302) : Temperature dependence of thermal conductivity of sintered superconducting Y1-xSmxBa2Cu3O7-<100> pellets. Indian J Phys-Pt A 2001, 75(6), 597-602.

Thermal conductivity of a set of Y1-xSmxBa2Cu3O7-δ (with x = 0 - 1) superconducting pellets in the temperature range 20-150K has been reported. Sm-substitution in YBCO is found to influence the magnitude of thermal conductivity over the entire measured temperature range. In the normal state, thermal conductivity is dominated by phonon contribution, the electronic contribution amounts to <126> 15%. The analysis presented with the assumption of contribution from both phonons and electrons to the thermal conductivity peak below Tc, provides an excellent description of the measured data. Some of the microscopic quantities estimated using the best-fit parameters give reasonable values and are in fair agreement with other reports. Phonon - defect scattering is found to be <126>50% of the total scattering in the normal state thermal conductivity.

3 illus 43 ref

006646   Das T K;Sarkar H;Tarafdar G (Eastern Centre for Research in Astrophysics, Institute of Radiophysics & Electronics, 92, A P C Road, Kolkata-700 009) : Wide band spectral character vis-a-vis optical thickness of solar radio bursts. Indian J Phys-Pt B 2001, 75(5), 397-402.

Spectra fo solar radio bursts observed simultaneously in some of the selected frequencies in the band 0.245-15.4 GHz (1.95-122.45 cm-λ), have been studied. The variation of spectral nature due to the variation of the magnetic field of the underlying active regions, and also due to the change in the heliographic position of the bursts on the solar disc, has been investigated as well. The directivity and the optical thickness have been found out in the aforesaid waveband after an extensive study on a large number of discrete events. An empirical relationship has been invoked for showing the variation of optical thickness with the observing wavelength of radio bursts occurring in the central region of the disk. From this relationship, it can be concluded that the variation of optical depth with the wavelength gives rise to a U-shaped pattern, attaining the minimum value around 1 GHz (30 cm-λ). A comparative study between the spectral nature and the optical thickness of solar radio bursts observed in a wide band of wavelengths, has been made.

6 illus, 1table, 15 ref

006645   Chakraborty B;Bhattacharya R;Paul S N (Department of Mathematics, Jadavpur University, Kolkata-700 032) : Classical physics of magnetic moment. Indian J Phys-Pt B 2001, 75(5), 439-46.

Excitation of magneto-static field in matter is essentially due to orientation and distribution of magnetic moment of material charges, whatever be its apparent explanation classically and phenomenologically. Classical physics of magnetic moment which is a primary source of magnetization in matter, has been developed systematically for various applications, including particularly those of determination of the DC moments in problems of wave plasma interactions as well as wave-wave interactions in plasma.

23 ref

006644   Borthakur T K;Mohanty S R;Bhuyan H;Rai V N (Centre of Plasma Physics, , Dispur, Guwahati-781 006) : Analysis of soft X-ray emission from a low energy plasma focus device using vacuum photodiode. Indian J Phys-Pt B 2001, 75(5), 455-8.

Temporal evolution of soft X-ray emission from a 2.2 kJ Mather type plasma focus device has been studied for the first time using X-ray vacuum photodiode. The X-ray emission study was performed in gas medium such as nitrogen, hydrogen and argon. It is noted that X-rays are emitted in the form of multiple pulses.

22 ref

006643   Bhattacharya S (Department of Organic Chemistry, Indian Institute of Science, Bangalore-560 012) : Supramolecular association as the basis of materials design. case studies with hydrogels and organogels. J Indian Inst Sci 2001, 81(1), 37-42.

Molecular designs of several low molecular mass gelators for aqueous and organic media are presented. It is found that gelation requires strong intermolecular association, which eventually produces superamolecular networks. Solvent molecules get entrapped into these highly entangled networks, presumably due to surface tension. From a two-phase mixture comprising an upper oily layer of commercial fuels and a lower aqueous layer, N-Lauroyl-L-alanine is able to gelate the oil selectively.

28 ref

006642   Bhagwat K V;Karmakar D (Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Trombay-400 085) : Magnetization curves for general cylindrical samples in a transverse field. Pramana J Phys 2001, 57(4), 763-74.

Using the recent results for the surface current density on cylindrical surfaces of arbitrary cross-section producing uniform interior magnetic field proposes a method for obtaining solutions of Bean's critical state model for general cylindrical samples. The method uses the technique of conformal mapping to express the sample surface and the flux-fronts in terms of a set of coefficients that depend on a parameter. The flux-fronts are to be determined by solving a system of nonlinear ordinary differential equations for the coefficients. Retaining only a certain finite number of leading coefficients we get an approximate solution. The procedure is illustrated by considering two cylindrical samples-one with an elliptical cross-section and the other with a non-elliptical cross-section. The virgin curve and small and large magnetization hysteresis loops for the two samples are obtained.

4 illus, 21 ref

006641   Bannur V M (Department of Physics, University of Calicut, Calicut-673 635) : Neutrino beam plasma instability. Pramana J Phys 2001, 57(4), 755-61.

Derives relativistic fluid set of equations for neutrinos and electrons from relativistic Vlasov equations with Fermi weak interaction force. Using these fluid equations, Obtains a dispersion relation of streaming instability. It contains new, nonelectromagnetic, neutrino-plasma (or electroweak) stable an unstable modes also. The growth of the instability is weak for the highly relativistic neutrino flux, but becomes stronger for weakly relativistic neutrino flux in the case of parameters appropriate to the early universe and supernova explosions. However, this mode is dominant only for the beam velocity greater than 0.25c and in the other limit electroweak unstable mode takes over.

1 illus, 8 ref

006640   Arjuna Gowda K V;Kokila M K;Puttaraja; Kulkarni M V;Shivaprakash N C (Department of Physics, Bangalore University, Jnanabharathi Campus, Bangalore-560 056) : Crystal and molecular structure of 2-phenyl-3N-[3"-chloro-4"-fluoro)phenyl]-4-thiazolidinone. Indian J Phys-Pt A 2001, 75(6), 603-06.

Crystal and molecular structure of 2-phenyl-3N-[3"-chloro-4"-fluoro) phenyl]-4-thiazolidinone have beem determined by X-ray structure analysis. They belong to the family of thiazolidinones. The structure was solved by direct method. The molecular packing of the non-planar moleculars are held by Van der Waals interactions.

3 illus, 13 ref

006639   Ammar A H;Farag E M (Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt) : Effect of pressure and temperature on the conductivity and sensitivity of SnO2/Pt based sensors. Indian J Phys-Pt A 2001, 75(6), 633-8.

Temperature dependence of conductance of SnO2 thin film (doped with 10 nm Pt) gas sensors is obtained in the temperature range 300K to 700K at different partial pressure of NH3 and CO in nitrogen. The measurements are carried out using different heating and cooling rates. The proposed model takes into account the dependence of film conductivity on both the partial pressure and environment-temperature. The sensor sensitivities were studied in (10^-4 vacuum mbar), in air and in N2. The sensitivities to NH3/N2 and CO/N2 gases were studied in the temperature range 313 to 673K with different ambient temperatures and pressures. The best sensitivity, stability, and optimum work temperature were obtained with CO/N2 at a pressure <126> 100 mbar and ambient temperature 433K.

7 illus, 16 ref

005589   Zomorrodian M E (Department of Physics, Ferdowsi University, Mashhad) : Comparison of quark jets and gluon jets produced in high energy e<. Indian J Phys-Pt A 2001, 75(5), 557-60.

Experimental comparison of the characteristics of quark induced and gluon induced jets based on an analysis of jet events selected from hadronic events observed at c.m. energy of 60 GeV in electron - positron annihilations. The mean transverse momentum (PT) with respect to the jet axis is larger for three jet events than the corresponding value for the two jet events. This is in qualitative agreement with the QCD theory which predicts a more chance of gluon radiation in three jet events. furthermore, the particles in the gluon enriched sample have a higher multiplicity than its counterpart in quart jet sample. The ratio of the two multiplicities is 1.3 + - 0.02. This numerical value is in good quantitative agreement with the OPAL experiment. Possible explanation for all these features has been presented.

9 illus, 13 ref

005588   Zayed H A;Soliman L I;Farag B S;Shehata F M (NO, , ) : Transport properties of SnTe_xSe_1-x thin films. Indian J pure appl Phys 2001, 39(10), 654-60.

Ternary semiconductos SnTe_xSe_1-x (where 0≤ x ≤1), were prepared by fusion method. The Sn Te_x1-x thin films were prepared by thermal evaporation under vacuum of about 10^-5 Torr. The structure and the composition analysis of SnTe_xSe_1-x in powder and thin films form were investigated by X-ray diffraction and microprobe analysis technique respectively. It was found that the electrical conductivity σ increases, while the activation energy decreased with increasing composition (x). The thermoelectric power and Hall voltage measurements indicated that the SnTe_xSe_1-x thin films were P-type conduction. The SnTe_xSe_1-x thin films were non-degenerate semiconductor for all values of x from zero to 0.8, while for SnTe (x=1) the films were degenerate and had a metallic behaviour. Moreover the carrier density P was changed from <126> 10¹⁷ to 10²¹ cm^-3 as X changed from zero to one. It was found that the mobility of SnTe_xTe_1-x thin films increased as x increased, which indicated the presence of two types of scattering mechanisms, namely ionized impurity scattering as well as grain boundary potential barrier scattering. The effective mass m⁴² of SnTe_xSe_1-x thin films were found to increase with composition x.

8 illus, 2 tables, 29 ref

005587   Zanatta A R;Fajardo F;Mulato M;Lima JR M M; Marques F C;Chambouleyron I (NO, Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Sao Carlos, Brazil) : RF sputtered a-Si:H and a-Ge:H films: a comparative study. Asian J Phys 2000, 9(3), 681-92.

Different correlations have been reported concerning the sputtering (sp) method and the nature of the most influential species in the plasma. However, the absence of detailed experimental information referring to the specific characteristics of each deposition system, such as the chamber geometry, the pumping setup and speed, the electrode size and spacing, etc., makes almost impossible (and useless) the direct transfer of deposition conditions from system to system. In other words, it is very hard to reproduce the properties of a-films in different deposition systems. Moreover, there are no studies comparing the properties of a-Si:H and a-Ge:H deposited in the same system under similar conditions.

5 illus, 2 tables, 33 ref

005586   Yazar H R;Colakoglu K (Department of Physics, Kirikkale University, 71450 Yahsihan, Kirikkale, Turkey) : Analysis of the pressure dependence of some thermodynamic properties of NaCl-structure alkali halid crystals using woodcock potential. Indian J Phys-Pt A 2001, 75(5), 503-06.

Applicability of the Woodcock potential form is considered for studying the effect of the pressure of NaCl - crystal. This potential form represents the composite form of the inverse power dependence and exponential dependence of the repulsive energy on interionic distance. Pressure dependence of Debye temperature, volume expansion coefficient and pressure - volume relation are calculated for NaCl - crystal. The results are discussed and compared with available experimental data.

1 illus, 3 tables, 15 ref

005585   Yannopoulos S N;Papatheodorou G N (NO, Institute of Chemical Engineering and High Temperature Chemical Proce, Hellas, P.O. Box 1414, GR-26500 Patras, Greece) : Dynamics of inorganic glass-forming liquids: results from light scattring investigations. Asian J Phys 2000, 9(3), 531-42.

Dynamics of density and orientation fluctuations from microscopic up to macroscopic time scales are studied by means of dynamic light scattering techniques. Reports the experimental studies (Rayleigh-Brillouin scattering, Photon correlation spectroscopy and Low frequency Raman scattering) for particular moleten salts and oxide glasses. Results are discussed in the framework of current theoretical approches and Phenomenological models of the field.

5 illus, 26 ref

005584   Virk H S;Walia V;Bajwa B S (Department of Physics, Guru Nanak Dev University, Amritsar-143 005) : Radon monitoring in underground water of Gurdaspur and Bathinda districts of Punjab, India. Indian J pure appl Phys 2001, 39(11), 746-9.

Radon monitoring has become a global phenomenon due to its health hazard. More than 55% radiation dose delivered to the human kind on the globe from all natural sources is due to radon alone. Radon measurements have been carried out in groundwater in Gurdaspur and Bathinda districts of Punjab, India. Radon concentration values in potable water show a wide variation depending on its source and location. Generally, radon concentration values in hand-pump drawn groundwater have been found to be higher than the values determined for water supplied from other sources. Mineral water has the minimum radon concentration compared with groundwater sources. No correlation is found between radon concentration and uranium content of groundwater in Bathinda district.

3 tables, 21 ref

005583   Verma R C;Khanna M P (Department of Physics, Punjabi University, Patiala-147 002) : Strong BBP couplings for the charmed baryons. Indian J pure appl Phys 2001, 39(10), 615-22.

According to the Coleman-Glashow null theorem if all the symmetry breaking effects belong to the same regular representation (octet in the case of SU(3) and 15 in the case of SU(4)) and are generated in a tadpole type mechanism, the strangeness changing (charm changing) weak transitions generated through the S₆ (S₉) tadpole must vanish. Exploiting this mull result, relations between the BBP coupling constants are obtained, which leads to the coupling constants in terms of two parameters and baryon masses. Fixing these two parameters (g_NNπ and g_ΛΣπ) from experiments, the remaining coupling constants are estimated.

1 table, 18 ref

005582   Verma A S (Department of Physics, Govt. P.G. College, Guna-473 001) : Applications of single injection solid state diodes in electronic circuits and photoconductivity. Appl Sci Period 2001, 3(1), 1-2.

Some experimental aspects of the single injection solid state diodes in electrical circuits and photo conductivity have been discussed.

7 ref

005581   Venkat Ramulu N;Aparna M;Prasad G;Kumar G S; Bhima Sankaram T (Materials Research Laboratory, Department of Physics, Osmania University, Hyderabad-500 007) : Impedance spectroscopic studies in SrBi₄Ti₄O₁₅. Indian J pure appl Phys 2001, 39(11), 718-25.

Impedance measurements have been performed in the temperature range of 30 to 600°C and the frequency range 1 kHz to 10 MHz on four-layered SrBiv>4Ti₄O₁₅. The imaginary components of impedance Z", the electrical modulus M" and ac conductivity have been computed, both as a function of frequency and temperature. The peaks appear in Z" versus frequency plots and they shift towards lower frequencies at the temperature up to 500°C and above 525°C they shift towards higher frequencies. Similar behaviour is observed in M" versus frequency plots. <157>Z"<157> values decrease with increase of temperature, while <157>M"<157> values decrease up to 500°C and above 525°C these values are found to increase with temperature. Complex impedance diagrams are nearly semicircles at higher temperatures. Results are interpreted in terms of possible conductivity mechanisms present in the sample.

9 illus, 11 ref

005580   Tsybeskov L;Lockwood D J (Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York-14627, USA) : Quantum confinement in nanocrystallne silicon superlattices. Asian J Phys 2000, 9(3), 745-57.

Effect of quantum confinement in nanocrystalline silicon superlattices composed of Si nanocrystals nearly monodispersed in size vertically separated by SiO₂ layers is discussed. A comprehensive structural, optical, and electrical characterization of this system indicates flat and atomically abrupt Si/SiO₂ interfaces and a low defect density. A convincing demonstration of quantization in dispersion of acoustic phonons and of electron-hole pairs has been presented. This novel fabrication technique, with angstrom accuracy, is very promising for nanoscale electronic and optoelectronic device manufacturing.

7 illus, 26 ref

005579   Tikhomirov V K;Perakis A;Sarantopoulou E; Seddon A B (Department of Materials, University of Leeds, Leeds LS2 9JT, UK) : Origin of the boson peak in the Raman spectra of glasses. Asian J Phys 2000, 9(3), 551-9.

Presents data on the influence of doping with rare-earth ions and of the light irradiation on the Boson peak in the Raman spectra of glasses which indicate that non-bridging anions (such as S, O, F) or strained anion bonds determine the origin of the peak. A temperature dependence of the shape of the peak indicates two contributions to its intensity originating probably from two different metastable atomic configurations in the vicinity of such anions. A polaritonic character of interaction of light with low-energy phonons giving rise to the Boson peak and a frequency matching of the peak with an analogue peak in the crystalline counterpart indicate that it is probably optical TO-phonons which determine the Boson peak in glasses.

5 illus, 1 table, 26 ref

005578   Theye M L;Paret V (Laboratoire d'Optique des Solides, UMR CNRS 7601, Universite P. et M. Curie - Paris 6, Boite 80, 4 place Jussieu, F - 75252 Paris Cedex 05, France) : Characterization of the vibrational properties of a-C:H films by hydrogen/deuterium substitution. Asian J Phys 2000, 9(3), 657-69.

Vibrational properties of hydrogenated amorphous carbon films as determined from the analysis of their infra-red absorption spectra can give very useful information on the complex microstructure of these samples. To be able to distinguish and identify the respective contributions of the C-H and C-C bonds vibration modes in the infra-red absorption, systematically compared the data obtained between 500 and 4000 cm^-1 on hydrogenated and deuterated films prepared by a PECVD technique under identical conditions from CH₄ and CD₄ respectively. The results are interpreted in terms of the modifications of the material microstructure when increasing the ion bombardment during deposition.

5 illus, 2 tables, 24 ref

005577   Teli M T;Mahajan C S;Nathuram R (Department of Physics, Nuclear Research Laboratory, Dr Babasaheb Ambedkar Marathwada University, Arungabad-431 004) : Measurement of mass and linear attenuation coefficients of gamma rays for various elements through aqueous solution of salts. Indian J pure appl Phys 2001, 39(12), 816-24.

Solution technique is developed for the measurement of linear and mass attenuation coefficients of salts for gamma-rays and from them elemental attenuation coefficients are estimated. Improved mixture rule 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.

3 illus, 2 tables, 18 ref

005576   Taqi A H;Radhi R A;Ahmed A K (Department of Physics, College of Science, Saddam University, Baghdad, Iraq) : Collective, low-lying isoscalar transitions in <. Indian J Phys-Pt A 2001, 75(5), 569-71.

Collective, low-lying isoscalar transition in ⁴⁰Ca are investigated in the framework of the random phase approximation (RPA). These states include the isoscalar states J^π(Ex MeV) : 3^-(3.74), and 5^- (4.48). Admixture of higher orbits with the particle-hole pairs already present in the ground state, is taken into consideration. Configurations outside the model space are included, approximately in polarization effective charges. Longitudinal C3 and C5 electron scattering form factors for these status are calculated and compared with the experimental data. Overall agreements are obtained.

^ssc2 illus, 9 ref

005575   Tanaka K;Hisakuni H (Department of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan) : Mechanisms of photoinduced light "scattering" in As₂S₃ glass. Asian J Phys 2000, 9(3), 723-9.

Chalcogenide glasses exhibit isotopic and anisotropic light "scattering" upon unpolarized and polarized sub-bandgap illumination. The mechanism has been ascribed to the photocreation of light-scattering centers. It asserts that the phenomenon is caused by photoinduced persistent self-focusing structures, which are birefringent under polarized illumination.

5 illus, 18 ref

005574   Sunandana C S (NO, School of Physics, University of Hyderabad, Hyderabad-500 046) : ESR-a technique exclusive for understanding semiconductor processes. Indian J pure appl Phys 2001, 39(12), 810-15.

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 a-Si3N4 have been discussed, in an attempt to demonstrate the power of the technique. Some problems for the future are indicated.

7 illus, 8 ref

005573   Subbalakshmi P;Veeraiah N (Department of Physics, Nagarjuna university P G Centre, Nuzvid-521 201) : Influence of WO₃ on dielectric properties of zinc phosphate glasses. Indian J Engng Mater Sci 2001, 8(5), 275-84.

Dielectric constant ε', loss tan δ and a.c conductivity σ_a.c of 40 40 ZnO_-x WO₃- (60_-x) P₂O₅ (with 0 ≤ x ≤ 15) glasses are studied as a function of frequency (in the range 10²-10⁵ Hz) and temperature (range 30-300°C). The dielectric breakdown strengths of these glasses are also measured in the air medium. All the dielectric parameters (viz., ε', tan δ and σ_a.c) are found to decrease with the increase in the concentration of WO₃. Dielectric loss variation with the temperature for the glasses containing WO₃ up to 5 mol % exhibited dipolar relaxation effects. These effects are analysed by a pseudo Cole-Cole plot method. The dielectric breakdown strength, the activation energy for a.c. conduction are found to decrease with increase in concentration of WO₃. These results have been used to throw some light on the structural change in ZnO-WO₃-P₂O₅ glass system with the aid of data on IR spectra and differential thermal analysis of these glasses.

9 illus, 4 tables, 46 ref

005572   Srirang Manohar;Asokan S;Gopal E S R (Department of Instrumentation, Indian Institute of Science, Bangalore-560 012) : Photoacoustic spectroscopy and its application to chalcogenide glassy semiconductors. Asian J Phys 2000, 9(3), 589-608.

Reviews the Photoacoustic technique and its application in spectroscopic and calorimetric studies on chalcogenide semiconducting glasses. A detailed analysis of the Photoacoustic (PA) signal production is presented, showing the signal dependence on the optical, thermal and geometric parameters of the sample and the other interacting layers that are part of the system. Particular attention is focussed on the conditions under which optical absorption spectra and thermal properties of the sample can be elicited from the signal. The experimental procedures for measuring the above mentioned parameters of the sample are described. Finally, a review of studies conducted on several chalcogenide based semiconducting glasses is presented.

11 illus, 1 table, 75 ref

005571   Shirai H;Jung J;Fujimura Y;Fukai C;Toyoshima Y (Department of Functional Materials Science, Faculty of Engineering, Saitama University, 255 Shimo-Okubo, Urawa-shi, Saitama-338-8570, Japan) : Low temperature plasma CVD of crystal silicon film growth from chlorinated species. Asian J Phys 2000, 9(3), 823-32.

Growth of hydrogenated chlorinated crystal silicon film from highly H₂-diluted dichlorosilane (SiH₂Cl₂) and trichlorosilane (SiHCl₃) systems by a conventional rf glow discharge is discussed. Compared with the conventional SiH₄/H₂ system, film crystallinity is significantly enhanced from initial growth stage even on glass at low temperatures. The role of chlorine and hydrogen in crystal formation are discussed in terms of gas phase and surface chemistry through the film deposition and in situ monitoring of the gas phase and surface chemistry through the film deposition and in situ monitoring of the gas phase and surface reactions. It is found from infrared reflection-absorption spectroscopy (FTIRRAS), that the growing top surface is terminated by chlorine in the form of Si-Cl, rather than hydrogen. The chemical stability is improved to the H₂ and B₂H₆ plasmas compared with that in the SiH₄/H₂. The influences of the PH₃ and B₂H₆ impurity doping on the electronic transport and optical properties are also demonstrated.

8 illus, 14 ref

005570   Shashidharan P;Gokhale N A;Gadkari D B;Lal K B;Gokhale M R;Arora B M (Department of Physics, Vartak College, Vasai Road (W), Mumbai-401 202) : Effect of in content in In_xGa_1-xSb on breaking of ampoule during growth by vertical directional solidification. Indian J pure appl Phys 2001, 39(11), 704-6.

In GaSb crystals have been grown using vertical directional solidification (VDS) technique in closed conical quartz ampoules. IN_x Ga_1xSb Crystals with different In mole fractions in the melt (x=0.1, 0.25, 0.5 and 0.75) have been grown to study the effect of mole fraction in the breaking of the ampoule. Growth with In mole fraction x = 0.5 in the melt resulted in breaking of the ampoule. For other compositions, no breaking of the ampoule occurred. The problem of breaking of ampoule was circumvented by encapsulating the material containing quartz ampoule in another quartz ampould. The double ampoule prevents the melt from coming into contact with atmospheric air in case of a breakage enabling the growth of crystals from melts with 50% In composition. Sticking of the ingot to the ampoule has not been observed for any of the compositions.

2 illus, 9 ref

005569   Sharma A K;Suresh Chandra (NO, B.R.C.M College of Engineering and Technology, Bahal-127 028) : Detection of rotational lines of NaSH molecule. Indian J pure appl Phys 2001, 39(12), 765-7.

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 (μb = 0.63 D) as compared to a-component of electric dipole moment (μa = 7.91 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.

1 illus, 2 tables, 7 ref

005568   Sathish L A;Sannappa J;Paramesh L; Chandrashekara M S;Venkataramaiah P (Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore-570 006) : Indoor radon/thoron and their progeny levels at Mysore city, Karnataka state. Indian J pure appl Phys 2001, 39(11), 738-45.

Radon, thoron and their progeny concentrations have been measured in different types of buildings at different locations in Mysore city over a period of 2 years using solid state nuclear track detector (SSNTD) method. The dose to the selected population of Mysore city has been estimated. The arithmetic mean (AM) values of concentrations of radon and thoron in indoor atmosphere ranged from 9.20 to 58.02 Bq m^-3 with a median of 34 Bq m^-3 and 7.21 to 59.27 Bq m^-3 with a median of 3 Bq m^-3, respectively. The arithmetic mean of progeny concentrations varies from 0.033 to 2.52 mWL with a median of 1.29 and 0.074 to 47.04 mWL with a median of 20.7, respectiely. The dose to the selected population of Mysore city has been found to be 1.58 mSv y^-1. The concentrations of radon/thoron and their progeny vary with the type of flooring and ventilation conditions. Diurnal and seasonal variations have also been observed. Higher radon concentration has been found during nights and early morning hours.

3 illus, 3 tables, 8 ref

005567   Sarkar S;Goswami T D (Department of Physics, Gauhati University, Guwahati-781 014) : Transverse flow of nuclear matter in hadron-nucleus interactions. Indian J Phys-Pt A 2001, 75(5), 553-6.

Emission of black particles from high-energy hadron-nucleus interactions takes place from a thermally non-equilibrated excited nucleus. The angular distribution of these particles shows an abundance of emission along transverse direction.

4 illus 11 ref

005566   Sameshima T (NO, Tokyo A and T University, 2-24-16, Nakamachi, Koganei, Tokyo, 184-8588, Japan) : Electronic and crystallographic properties of polycrystalline silicon films. Asian J Phys 2000, 9(3), 773-97.

Fundamental properties of silicon films crystallized by a 30-ns-pulsed XeCl excimer laser are discussed. Analyses of free carrier optical absorption revealed that crystalline grains with a small size 10-50 nm had excellent electrical properties with a high carrier mobility, while grain boundaries had a high defect density resulting in low effective mobility of electrical current traversing grain boundaries. Reduction of density of defect states was demonstrated by oxygen plasma treatment as well as high-pressure H₂O vapor annealing at low temperatures <60> 300°C. Increase in the carier mobility to 500 cm²/Vs was demonstrated in the polycrystalline silicon thin film transistors fabricated in laser crystallized silicon films. Formation of large crystalline grains 3.5 μm were demonstrated using the electrical current induced joule heating method.

13 illus, 40 ref

005565   Saikia J;Changmai R;Baruah G D (Department of Physics, Laboratory of Non-linear Optics and Laser, Dibrugarh University, Dibrugarh-786 004) : Bioluminescence of fireflies and evaluation of firefly pulses in light of oscillatory chemical reactions. Indian J pure appl Phys 2001, 39(12), 825-8.

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 A. 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.

5 illus, 1 table, 15 ref

005564   Roy R S (Postgraduate Department of Physics, Rajendra College (J.P. University), Chapra) : Mechanoluminescence and deformation bleaching in coloured alkali halide crystals. Asian J Chem 2001, 13(3), 867-75.

Reports the mechanoluminescence (ML) and deformation bleaching of a colouration in coloured alkali halide crystals. As the F-centre electrons captured by moving dislocations are picked up by holes, deep traps and other compatible traps, so deformation bleaching occurs. Simultaneously radiative recombination of dislocation captured electrons with the holes gives rise to the mechanoluminescence. Expressions have been derived for the strain dependence of the density of colour centres is deformed crystals and for the number of colour centre bleached. So far as strain, temperature, density of colour centres, Ea and volume dependence are concerned, there exists a correlation between the deformation bleaching and mL in coloured alkali halide crystals. From the strain dependence of the density of colour centres in deformed crystals, the value of coefficient of deformation bleaching D is found to be 1.929 and 1.990 for KCl and KBr crystals respectively. The value of (D + χ) as determined from the strain dependence of the ML intensity is found to be 2.59 and 3.69 for KCl and KBr crystals respectively. This gives the value of coefficient of deformation generated compatible traps χ to be 0.68 and 1.69 for KCl and KBr crystals respectively.

22 ref

005563   Rocca F;Dalba G;Daldosso N (CeFsa, Centro CNR-ITC di Fisica degli Stati Aggregati, , I-38050 Povo (Trento), Italy) : Structure of nanocrystalline materials analyzed by X-ray absorption fine structure: the case of porous silicon. Asian J Phys 2000, 9(3), 759-71.

X-ray absorption fine spectroscopy (XAFS) has been established as a suitable tool for the determination of the atomic scale structure of nanocrystalline materials. Reviews the potentialities and limits of the XAFS techniques when applied to the study of nanocrystalline systems. Particular attention is devoted to photoluminescence yield XAFS technique for its site sensitivity in quantum confined luminescent nanosystems. The results relative to the local structure of the luminescent sites of porous silicon are reviewed.

5 illus, 35 ref

005562   Rewar G D;Bhatnagar D (Microwave Laboratory, Department of Physics, University of Rajasthan, Jaipur-302 004) : Dielectric relaxation studies of ternary mixtures of non-rigid polar liquids in the MW region. Indian J Phys-Pt A 2001, 75(5), 541-5.

Dielectric behaviour of three Acrylates and their mixture compositions as liquid dielectric samples, have been studied at MW frequency 9.132 GHz in dilute solution of carbon tetrachloride in the temperature range 300K to 330K. Different dielectric parameters like dielectric constant ε∞ dielectric loss ε at microwave frequency, static dielectric constant εs and dielectric constant ε∞ at optical frequency have been determined. Using these dielectric data, various relaxation times viz τ0, τ1 and τ2, of individual components and their ternary mixture compositions have been calculated. The relaxation time values for single component solutions agree well with literature values while relaxation times of ternary mixture composition are consistent with the computed values obtained from various theoretical relations.

2 illus, 2 tables, 11 ref

005561   Ramchand C N;Pande P;Kopcansky P;Mehta R V (Sun Pharma Advanced Research Centre, , Akota Road, Akota, Baroda) : Application of magnetic fluids in medicine and biotechnology. Indian J pure appl Phys 2001, 39(10), 683-6.

The applications of magnetic fluids in other fields are also manifold. Magnetic for isolating mRNA are quicker and more efficient, and they avoid organic solvents and the need for a precipitation step. Magnetic beads linked to high affinity capture antibodies have been widely accepted as separation techniques of specific target ligands or particles such as bacteria orleukocytes from complex mixtures, such as bone marrow, blood and other body fluids. Detection of contaminating microorganisms like staphylococcus sp. In milk using a magnetic based ELISA (Enzyme Linked Immunosorbent Assay) has been developed. It is also proposed to use this technology to immobilize polymixin B antibiotic for the treatment of endotoxic shock. The extreme toxicity of this antibiotic could be avoided using dialysis to remove the magnetically bound antibiotic, from systematic circulation, after its action. Similarly using magnetically immobilized antifungal agent amphoterecin, for systemic application, could reduce toxicity of this antifungal agent. Investigating the use of magnetically immobilized Horseshoe crab protein for combating endotoxic shock could also prove to be an effective line of treatment. Using magnetic particles as such or erythrocyte ghost preparations of the same could be used as an opaque medium in angiography and radiography techniques. In addition to this, using magnetically immobilized microorganisms for wastewater treatment is an extremely cost effective technology.

16 ref

005560   Radhi R A (Department of Physics, College of Science, University of Baghdad, Baghdad, Iraq) : Higher configurations-effect on the form factors in <. Indian J Phys-Pt A 2001, 75(5), 547-51.

Core-polarization effect on electron scattering form factors are calculated for the low-lying levels of ⁹Be (2.429 MeV, 5/2^- and 6.76 MeV, 7/2^-) and for the ground state of ¹⁹F. The calculation has been performed within the framework of microscopic theory that includes core-polarization effects. An over all agreement with the experimental data is obtained for the two low-lying levels in ⁹Be. Results agree very well with the intermediate maximum as well as the entire range of momentum transfer data for ¹⁹F.

6 illus 17 ref