020849   Arulsamy A D (Physics School, The Univ of Sydney, Sydney, New South Wales 2006, Australia, Email: andrew@physics.usyd.edu.au) : Many-body hamiltonian with screening parameter and ionization energy. Pramana J Phys 2010, 74(4), 615-31.

Proves the existence of a Hamiltonian with ionization energy as part of the eigenvalue, Which can be used to study strongly correlated matter. This eigenvalue consists of total energy at zero temperature (EO) and the ionization energy (…). Shows that the existence of this total energy eigenvalue, Eo ±…, does not violate the Coulombian atomic system. Since there is no equivalent known Hamilton operator that corresponds quantitatively to …, we employ the screened Coulomb potential operator (Yukawa-type). which is a function of this ionization energy to analytically calculate the screening parameter (cr) of a neutral helium atom in the ground state. In addition, we also show that the energy level splitting due to spin-orbit coupling is inversely proportional to … eigenvalue, which is also important in the field of spintronics.

1 table, 27 ref

000082   Flex Products Inc (NO, , 2793 Northpoint Parkway, Santa Rosa, California 9507, USA) : Viewing device for checking the authenticity of an instrument of value. 0000, (NULL), (NULL).

000081   Verma R N;SahaD P;Singh S (Department of Physics, UP College, Varanasi-221 002) : Polycrystalline ZnSe under solar illumination. Indian J pure appl Phys 2001, 39(4), 271-4.

Carrier generation rates of electron-hole pairs in polycrystalline zinc selenide (ZnSe) photovoltaic material have been computed for the first time for AM0, AM1, AM1.5 solar spectra. These theoretically computed actual generation rates have been replaced by a curve fitted approximation, which are represented by a series of three exponential terms. A simplified theory has been used for evaluating the solar cell parameters viz J_sc, V_oc, FF and η for the various solar spectra.

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000080   Varshney D;Patel G S;Shah S;Singh R K (School of Physics, Vigyan Bhawan , Devi Ahilya University, Khandwa Road Campus, Indore-452 017) : Pairing mechanism and superconducting state parameters in YBa₂Cu₃Oμ. Indian J pure appl Phys 2001, 39(4), 246-58.

Nature of pairing mechanism and the superconducting state of bi-layer optimised hole doped Yttrium based cuprates have been theoretically investigated using the strong coupling theory. An interaction potential is set up which incorporates various interactions as hole-hole, hole-phonon and hole-plasmon with proper layered structure of the system. For the admissible value of interlayer phonons the deduced value of coupling strength favours the strong coupling regime and screening parameter infers the effective screening of holes as carriers. The transition temperature with the use of model coupling parameters is estimated as T_c^ph = 73.45 K. Incorporating the 2-D acoustic plasmons the T_c enhances to 90 K, which is in the measured range. The approach is further applied to evaluate the isotope exponent and the reduced total isotope exponent suggests and transition from phonon mediated superconductivity to dual phonon-electrnic boson mechanism in high-T_c Yttirum based systems. The energy gap ratio is substantially larger than BCS ratio and infers that the strong coupling effects are important. The implications of the co-operative phonon-plasmon approach are discussed.

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000079   Thakur N;Sharma D R (Department of Physics, Himachal Pradesh University, Shimla-171 005) : Dielectric relaxation of binary mixtures of acetonitrile and N,N-dimethyl formamide in benzene solution using microwave absorption studies. Indian J pure appl Phys 2000, 38(5), 328-30.

Dielectric relaxation time of CH₃CN and DMF in benzene solution has been calculated at 9.40 GHz from microwave absorption studies at different temperatures (25,30.35 and 40°C). Energy parameters (ΔHε, ΔFε, ΔSε) for dielectric relaxation process of (CH₃CN+DMF) mixture containing 50% of CH₃CN have been calculated at 25, 30, 35, 40°C and comparison has been made with corresponding energy parameters for viscous flow. It is found that dielectric relaxation process can be treated as rate process just like the viscous flow process. Based upon above studies solute-solvent type of molecular association has been proposed.

000078   Tezel O (Ondokuz Mayis University, Faculty of Science, Department of Physics, Kurupelit, Samsun, Turkey) : ESR of UV irradiated oxalic acid single crystal. Indian J pure appl Phys 2000, 38(5), 344-7.

UV irradiated samples of vacuumed powder and single crystal of oxalic acid two hydrate (C₂H₂O₄.2H₂O) have been investigated by the ESR method. The spectra of these single crystal and unvacummed powder have been attributed to radical. but the peaks belonging to this radical in the UV irradiated powder sample have not been observed on the spectrum after having been vacuumed. After A and g tensor values of this radical have been calculated. It was observed to be anisotropic. The g factor was found to be only very slightly anistropic with an average value of 2.00449. The hyperfine interaction tensors of the unpaired electron with the two H nuclei have been determined. At low temperature, the considerable change in the spectrum has not been observed.

000077   Teli M T;Jadhav G H (Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad-431 004) : Classical theory of weak interactions and vector bosons through four component electro-gravitodynamics. Indian J pure appl Phys 2001, 39(4), 191-7.

Generalized Dirac-Maxwell equations by breaking Lorentz conditions have been considered and potential fields from a point charge have been obtained. It is seen that the scalar components of fields create weak force and make the particles decay. The weak force is a vector field represented by vector bosons as carrier of weak interaction. The electromagnetic analogy is applied to gravitational field from a point charge.

000076   Singh N P;Singh A K (Department of Mathematics, VSSD College, Kanpur-208 002) : MHD effects on flow of viscous fluid with induced magnetic field. Indian J pure appl Phys 2001, 39(4), 240-5.

Flow of a viscous incompressible electrically conducting fluid in a rotating channel with non-conducting walls in the presence of uniform transverse magnetic field applied parallel to the axis of rotation is studied taking induced magnetic field into account. An exact solution of the governing equations is obtained in closed form for the fully developed flow. The expressions for the velocity field, induced magnetic field and shear stress are obtained. Results of the effect of rotational and magnetic parameters on primary and secondary flow have been presented. Also, the results on the effect of velocity and induced magnetic field on pressure gradient have also been presented.

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000075   Shukla S J;Jadhav K M;Bichile G K (Postgraduate and Research Center, Deogiri College, Aurangabad) : Study of bulk magnetic properties of the mixed spinel Mg Cr_xFe_2-xO₄. Indian J pure appl Phys 2001, 39(4), 226-30.

Polycrystalline samples of the mixed spinel series MgCr_xFe_2-xO₄ with x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0 have been prepared in the pellet form by standard ceramic technique and were studied by means of X-ray diffraction, magnetization and ac susceptibility measurements. The X-ray analysis shows that the samples are formed in a single-phase spinel structure. The lattice parameter a obtained from X-ray data increases initially upto x=0.4, and thereafter it decreases. The variation of the saturation magnetic moment per formula unit measured at 300K decreases with Cr content x. The ac susceptibility was measured from room temperature to 680 K. The Curie temperature obtained from ac susceptibility measurements decreases nearly linearly with the increase of Cr content x, suggesting the decrease in ferrimagnetic behaviour.

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000074   Shrivastava P K;Tiwari R K;Nigam S K (Department of Physics, Govt New Science College, Rewa-486 001) : Coronal index of solar activity and cosmic ray intensity variations. Indian J Phys-Pt B 2000, 75(1), 11-13.

Sunspot numbers, a reliable parameter of solar activity,l is generally used in cosmic ray modulation studies. Besides sunspot number, many other solar indices such as grouped solar flares coronal holes area have been used to study their relationship with cosmic ray intensity. However R_z, a indicator of solar activity, does not propagate in the interplanetary medium. Authors used a new index viz coronal index (CI) in cosmic ray modulation studies. CI is a full disk solar index and it may be calculated from ground-based patrol observations of the solar corona. This analysis indicates that the CI would be a better suited parameter for such studies.

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000073   Sharma R C;Sharma S (Department of Mathematics, Himachal Pradesh University, Summer Hill, Shimla-171 005) : On couple-stress fluid heated from below in porous medium. Indian J Phys-Pt B 2000, 75(1), 59-61.

A layer of couple-stress fluid heated from below in porous medium is considered. Using linearized stability theory and normal mode analysis, the dispersion relation is obtained. For stationary convection, the couple-stress postpones the onset of convection whereas the medium permeability hastens the onset of convection. The principle of exchange of stabilities is valid for the couple-stress fluid heated from below in porous medium.

000072   Sastry M;Gole A;Banpurkar A G;Limaye A V; Ogale S B (Materials Chemistry Division, National Chemical Laboratory, Pune-411 008) : Variation in viscous fingering pattern morphology due to surfactant-mediated interfacial recognition events. Curr Sci 2001, 81(2), 191-3.

Study of the formation of finger-like patterns during displacement of a viscous fluid by a less viscous one is of technological importance. The morphology of the viscous-finger patterns generated is a function of many parameters such as the flow rate, difference in viscosities of the two fluids and the interfacial tension. Demonstrates herein that the morphology of patterns formed during viscous fingering in a Hele-Shaw cell during displacement of paraffin oil by aqueous solutions of the surfactant sodium dodecyl sulphate (SDS), is extremely sensitive to interfacial tension variation brought about by complexation of divalent cations with the sufactant SDS. The variation in morphology of the patterns formed has been quantified by measuring the fractal dimensions of structures formed in a radial Hele-Shaw cell as well as the average finger width in a linear Hele-Shaw cell. This technique shows promise for studying other interfacial phenomena in chemistry such as biorecognition as well as dynamic processes occurring at interfaces.

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000071   Sarma L P;Gowd T N (National Geophysical Research Institute, , Hyderabad-500 007) : Raman and Brillouin scatterng studies on liquids and solids using an ultra high resolution spectrometer. Indian J pure appl Phys 2000, 38(5), 335-43.

Use of a state of the art ultra high resolution spectrometer (0.04 cm^-1) for both Raman and Brillouin scattering studies on liquids and solids has been reported. Thbmspectrometer calibrated with mercury lines has been standardized by resolving the isotopes of chlorine in the v₁ Raman mode of carbon tetrachloride (CCl₄). The spectra of Doppler shifted Brillouin doublets and central Rayleigh line for some molecular liquids; carbon tetrachloride (CCl₄), ultra pure water (H₂O), ethanol (C₂H₅OH), methanol (CH₃OH), propanol ((CH₃)₂CHOH), methylbutane ((CH₃)₂CH.CH.CH₃), amylacetate (CH₃COOC₅H₁₁), hydrogen peroxide (H₂O₂) and in natural minerals; hydrous quartz (SiO₂.nH₂O) and gypsum (CaSO₄.2H₂O) have been recorded and presented. The results demonstrate that the Brillouin doublets and the central Rayleigh line have been well resolved for their line shift, intensity and background. Sound velocities (v) and sound absorption (I_R/2I_B) calculated from the Brillouin shift and the integrated intensities of the Rayleigh and Brillouin doublets are compared with the available published data. The discrepancies between the measured V and I_R/2I_B (Landau and Placzek ratio) and those reported in the literature have been attributed mainly to velocity dispersion and thermodynamic dispersion respectively.

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000070   Ramanjappa T;Bhavani J A;Rajagopal E;Manohara Murthy N (Department of Physics, University of Botswana, Gaborone, Botswana) : Excess sound velocity and excess specific acoustic impedance of (2,2,2-trifluoroethan-1-01+benzene), (benzene+dimethyl sulphoxide) and (2,2,2-trifluoroethan-1-01+dimethyl sulphoxide) at 298.15 K. Indian J pure appl Phys 2000, 38(5), 301-5.

Excess sound velocity (U^E) and excess specific acoustic impedance (Z^E

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000069   Purohit P P;Pandey V P;Rajput B S (Department of Physics, Kumaun University, Nainital-263 002) : Scattering of monopoles and decay of anti-monopolium. Indian J pure appl Phys 2000, 38(5), 287-95.

Undertaking the study of behaviour of a spin-1/2 monopole moving in the field of mother monopole, Dirac's equation has been solved for energy eigen values and the Hamiltonian of this system has been shown to involve spin contribution. Spin momentum of a monopole has been shown to behave as extra energy source for monopoles interacting with electromagnetic field. Interaction of spin snd orbital moments of a monopole moving in the electromagnetic field has been analysed. S-matrix expansion, scattering amplitude and total Hamiltonian for monopole-anti-monopole scattering has also been undertaken. Study of bound state of a monopole and an anti-monopole has been carried out and it has been shown that this state is very short lived and decays in to two or three photons depending on the spin-statistics of the monopoles involved.

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000068   Pandey J D;Sharma A K;Pandey A;Soni N K; Murkherjee S (Department of Chemistry, University of Allahabad, Allahabad-211 002) : Molal volume of multicomponent liquid mixtures of non-electrolytes. Indian J pure appl Phys 2001, 39(4), 222-5.

Inspite of tremendous impressive developments of the molecular theory, an engineer frequently finds the need for physical properties, which have not been measured. The molal volume of a fluid at a given pressure and temperature is an equilibrium thermodynamic property. Wassiljewa equation in conjunction with Hildebrand's relation has been applied to evaluate molal volume of the various classes of liquid mixtures (binary, ternary and quaternary). It has the advantage over the empirical relations since it can be applied to a wide variety of fluids in moderate range. Moreover, it is very simple in form and the parameters have physical significance that is easy to conceive. It was observed after extensive fitting to the Hildebrand relation that V_o for most pure fluid range between 0.3 and 0.32 times the critical volume.

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000067   Nicula T (Military Chemistry Application School, , Str. Marasti 48, Campulung-Arges,-0425, Romania) : Particle size distribution measurements using polarized light methods. Indian J Phys-Pt B 2000, 75(1), 53-5.

Attention was paid to particle size distribution (PSD) measurements analyzing the polarization ratio of the light scattered by a polydisperse solution. The sample solutions were prepared mixing latex isotropic spheres of different sizes in order to simulate a variety of size distributions. The scattering computations have been performed to fit the experimental data and thus to determine the sample PSD. Measurements were made using an optical bench-mounted ellipsometer employing a laser diode source as light source.

000066   Navin Chand;Vashishtha S R (Regional Research laboratory(CSIR), , Habibganj Naka, Hoshangabad Road, Bhopal-462 026) : Melt flow studies of flyash particulate filled PP/PMMA blend. Clay Res 2000, 19(2), 49-56.

New type of filled blend material based on flyash (FA) particulate polypropylene/polymethyl methacrylate (PP/PMMA) blend having flyash loading ranging from 5 to 15 weight per hundred have been developed. Rheological data on filled blends are obtained by using a capillary rheometer at 220°C in shear rate range ranging from 10¹-10⁴ S^-1. It has been found that incorporation of flyash into PP/PMMA blend increased the melt viscosity and shear stress. It also reduced recoverable shear strain (S_R).

000065   Midya S K;Maitra S N;Tarafdar G (Department of Physics, Serampore College, Serampore, Hooghly-712 201) : Study of the variation of daily O₃ concentration at halley bay in antarctica with daily solar UV flux. Indian J Phys-Pt B 2000, 75(1), 15-18.

Atmospheric ozone even being a very minor constituent, plays a central role to absorb (not all) the solar UV radiations (200 nm to 320 nm) which are lethal to man and other living organisms. The ozone concentration is slowly declining every where throughout the world, but dramatic decrease of O₃ concentration takes place at Antarctica during spring time. Reports the investigation of the correlation coefficients of daily O₃ concentration of Antarctic survey station, Halley Bay with daily solar UV flux. Daily, monthly yearly and seasonal a correlation coefficients between O₃ concentration and UV flux are calculated from their corresponding daily, monthly, yearly and seasonal values. Concluded that atmospheric O₃ depletion over Antarctica is independent of solar UV radiation.

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000064   Mangla A;Sil A (School of Basic and Applied Sciences, Thapar Institute of Engineering and Technology, Patiala-147 004) : Transport characteristics of 0.3 KC1 : 0.7 ZrO₂ solid electrolyte. Indian J pure appl Phys 2001, 39(4), 267-70.

Composite solid electrolyte having composition 0.3 KC1 : 0.7 ZrO₂ (mol%) which is highly conducting in the system (1-x) KC1: x ZrO₂ has been prepared following the conventional ceramic powder processing route. The temperature dependent conductivity (σ) and mobility (μ) have been studied using complex impedance spectroscopy and transient ionic current techniques respectively. The notioceable conductivity enhancement is found to take place from 300°C at which the σ was 1.6 μS/m. The conductivity at 500°C up to which the measurements are taken is 1120 μS/m. The increase in the ionic mobility in the temperature range 300 to 460°C is found to be nominal. The temperature dependent carrier concentrations (n) as estimated from the temperature dependent σ and μ data has been found to increase from 7.24 x 10¹⁷ m^-3 (at 300°C) to 9.70 x 10¹⁹ m^-3 (at 460°C). This indicates that the ionic conductivity is predominaly governed by mobile ion concentration.

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000063   Lataifeh M S (Department of Physics, Mu'tah University, Mu'tah, Al-Karak, Jordan) : Magnetic and mossbauer spectroscopic study of some rare earth-iron intermetallic compounds. Indian J pure appl Phys 2000, 38(5), 331-4.

Magnetization measurements of the rare earth iron intermetallic compounds YFe₂ and Y (Fe_0.095 Co_0.05)₂ were made in the temperature range from 5 K to 300 K. The effect of increasing temperature on the saturation magnetization has been obtained. It was found that the introduction of cobalt with 5% concentration increases the saturation magnetization. This effect was attributed to the shift of 3d spin up band in Fe to lower energies and 3d spin down band to higher energies. Room temperature Mossbauer spectrum study of Y (Fe_0.095Co_{0.005)2 reveal that these systems are ferromagnetic. These have a high Curie temperature and the hyperfine magnetic field at the iron nucleus does not depend to a measurable extent on the magnetic properties of the rare earth atoms.}

000062   Khetrapal C L (NO, University of Allahabad, Allahabad-211 002) : Biomolecular structural studies using NMR. J Indian Chem Soc 2001, 78(3), 112-14.

During recent years, the use of dipolar couplings has gained prominence in biomolecular structural studies particularly with the discovery and use of lyotropic liquid crystalline media with low molecular orders and appropriate solubility properties. Though the idea of using dipolar couplings for such purposes has been there ever since the discovery of the technique of NMR spectroscopy of molecules oriented in liquid crystalline media nearly four decades back, practical difficulties such as the solubility and the spectral complexities in general have been responsible for such a long delay in actually exploiting the idea for biomolecular structural studies. During all these years attempts have been made by several active groups all over the world to overcome the difficulties, to use media with low order parameters and the discovery of new systems with desired solubility and the ordering properties. Such developments are discussed with emphasis on authors contributions and efforts in this emerging area of research.

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000061   Khah S K;Pourush P K S (Department of Instrumentation, Dau Dayal Institute of Vocational Education, Khandari, Agra-282 002) : Eight element circular array of circular patch microstrip antenna in dielectric medium. Indian J Phys-Pt B 2000, 75(1), 63-65.

Theoretical analysis of eight element circular array of circular patch microstrip antenna is proposed for X-band in plasma medium. The far-zone field patterns are obtained using vector wave function approach and analytical technique of microstrip antennas. The field patterns are plotted for both freespace and plasma modes. Other antenna parameters like half power beam width (HPBW), radiation conductance and directive gain are also computed. The results are used for the design of phased array antenna system in mobile communication systems.

000060   Jigeesh N;Radha Krishna Murthy A; Rangacharyulu M (Physics Department, Nagarjuna University, Nagarjuna Nagar-522 510) : Molecular force field of sulphadimethoxine. Indian J Phys-Pt B 2000, 75(1), 49-51.

Infrared and Raman spectroscopic study of the broad spectrum antibotic sulpha drug sulphadimethoxine have been made. Based on the assignments made to various vibrational frequencies, force constants are evaluated. Force constant studies are needed to have a qualitative study on the properties of molecules. The molecular model, the force constants and G matrices used for the molecule and the method of evaluation of force constants are given. The normal coordinate analysis is attempted on the molecule, treating it as an SO₂XY type molecule.

000059   Islam M N;Alam M K;Zaman M A;Molla N I (Institute of Nuclear Science and Technology, AERE, GPO Box 3787, Savar, Dhaka, Bangladesh, ) : Application of neutron radiography to building industries. Indian J pure appl Phys 2000, 38(5), 348-54.

Neutron radiography (NR) technique has been adopted to study the characteristics of some Bangladeshi building materials, e.g. bricks, ceramic bricks, heavy concrete, MS rod and shielding materials (borax mixed and boron carbide maixed shields) and some Slovanian building materials, local names of which are Siporex, Malta, Opeka and Beton. Measurements were made to determine defects in all the samples and water absorption behaviour of the Slovanian building materials. Optical density of the neutron radiographs was adopted for measurements in both the cases.

000058   Ishwara Bhat J;Shiva Kumar H R (Department of Chemistry, Mangalore University, Manalagangothri-574 199) : Acoustic and solvation behaviour of potassium thiocyanate in mixed solvents. Indian J pure appl Phys 2000, 38(5), 306-12.

Measurement of ultrasonic velocity and density at different concentrations of potassium thiocyanate in water, dimethylsulphoxide (DMSO), dimethylformamide (DMF) and their mixtures have been investigated at 298K using ultrasonic interferometer at frequency 2MHz. These data are used to evaluate adiabatic compressibility (βad), intermolecular free length L_f, specific acoustic impedance Z, relative association R_A, solvation number S_n, apparent molar compressibility O_k and molar volume O°_v. Gucker and Mason's relations have been verifield. Formation of complex at 60% DMSO and DMF has been identified in the system. These data are utilised in the qualitative study of ion-ion and ion-solvent interaction.

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000057   Gupta S J;Das R (Department of Physics, University of Mumbai, Mumbai-400 098) : Vibrational spectra of one-dimensional binary alloys. Indian J pure appl Phys 2001, 39(4), 213-21.

Vibrational frequency spectra of the random one-dimensional binary alloys A_cB_i-c have been accurately predicted by statistical theory of small clusters embedded in an effective medium (defect lattice potential). This is superior to the embedded cluster theory of one-dimensional linear chain of Myles and Dow. The local environment effect has been approximated by modifying CPA Green's function. Certain special and important cluster is treated as single defect embedded in the medium. The results are in excellent agreement with the exact numerical calculations.

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000056   Gupta J P;Abrol V (Environmental Assessment Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : Theory of purging of multireflection sample cell of an infrared gas analyser. Indian J pure appl Phys 2000, 38(5), 355-8.

Expression has been derived to explain the experimentally observed results of purging of a multireflection sample cell of an infrared gas analyser during its calibration and measurement. This expression can be used to calculate the actual concentration of the specific gas in a limited volume of a gas mixture insufficient to purge completely the sample cell.

000055   Gupta G P;Msezane A Z (Department of Physics, S D (Postgraduate) College, University of Meerut, Muzaffarnagar-251 001) : Energy levels, oscillator strengths and lifetimes in Mg-like sulphur. Indian J Phys-Pt B 2000, 75(1), 23-8.

Energy levels betwen the ground and the various excited states, oscillator strengths and transition probabilities for all dipole-allowed transitions among the 24 LS target states 3s²(¹S), 3s3p(^1.3p⁰), 3p²(¹S,³P,¹D), 3s3d(^1.3D), 3s4s(^1.3S), 3p3d(^1.3p^{0, 1.3D0, 1.3F0), 3s4p(1.3p0), 3s4d1.3D), 3s4f(0) and 3p4s(1.3p0)) of S V are calculated using program CIV3 of Hibbert. extensive configuration-interaction target wave functions are used in the calculation. From the transition probabilities, Evaluated radiative lifetimes of singlet and triplet states in S V. the calculated energy values, oscillator strengths and lifetimes are compared with the experimental and other theoretical results.}

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000054   Gopala Rao R V;Venkatesh R (Department of Chemistry, Banaras Hindu University, Varanasi-221 005) : Estimation of Gruneisen parameter and associated derived quantities. Indian J pure appl Phys 2000, 38(5), 313-18.

Value of Y^th, Y'_g, Q, (d In D/dp)_T, and C_v for several substances including C₆₀ have been calculated. In most cases the calculated values are in good agreement with literature values. It was found that in the case of the Anderson Gruneisen parameter δ_T is slightly on the higher side. The value of Q is negative for C₆₀ and for Cd. The values of Q, the second Gruneisen constant for all substances for which calculations have been made are found to be negative except in the case of Hg. In general Y'_g is small as expected. The pressure derivative of the diffusion coefficient for Hg is in excellent agreement with experiment. Made similar calculations of the quantities namely Y'_g, Q, and δ_T for C₆₀. The values of metallic Cd and that of C₆₀ which is classified as a metal give negative values. It is too early to conclude that all metals give negative values for Q until ample data is got. Suggested that Y^ex_g (external) for C₆₀ is significant used some value and obtained nearly the same value for y^th_g by two entirely differet methods.

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000053   Gohain Barua A;Baruah G D (Department of Physics, Gauhati University, Guwahati-781 014) : Propagation of dye laser beam through p-benzoquinone-H₄ vapour. Indian J pure appl Phys 2001, 39(4), 231-4.

Interaction of a tunable dye laser beam with p-benzoquinone-H₄ lines has been studied in the frequency range 17800-24900 cm^-1. Values of transmittance, averaged over intervals of 25 cm^-1, are obtained for three different path lengths-using the quasi-random model of molecular band absorption. From these values, intensities of the absorption lines are simulated.

000052   Garg M;Shyam Kumar;Quamara J K (Department of Applied Physics, Regional Engineering College, Kurukshetra-136 119) : Thermally stimulated depolarization current behaviour of 50 MeVLi<. Indian J pure appl Phys 2001, 39(4), 259-62.

Different dielectric relaxation processes such as dipolar and space charge have been investigated in high-energy ion-irradiated kapton-H polyimide using thermally stimulated discharge current (TSDC) technique. Kapton-H samples (12.5 μm thickness) are irradiated with Li⁺ ion (50 MeV0 at different flux (5x10⁵, 10⁵, 10⁴ opms/cm²) at Nuclear Science Center, New Delhi (PELLETRON facility). The thermoelectret of irradiated samples are prepared following the usual method for various poling fields and temperatures. The TSD currents are obtained at heating rate of 2°C/min. The peak appearing at low temperature and associated with dipolar polarization is largely affected in irradiated samples. This is mainly due to the dimerization of the carbonyl groups. The high temperature peak which is associated with space charge relaxation becomes more pronounced in irradiated samples. High-energy ion-irradiation provides deep energy trap centers in the form of conjugated bonds due to de-localized electrons. Low temperature tail of TSDC shows many kinks. These kinks are due to creation of new cross-linking dependent sub polar groups and shallow energy traps as a result of high-energy ion-irradiation.

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000051   Das R;Sahoo S;Roy K (Department of Theoretical Physics, Indian Association for the Cultivation of Science, Jadavpur, Calcutta-700 032) : Electron capture in H<. Indian J Phys-Pt B 2000, 75(1), 19-22.

Cross sections for one electron capture in proton-oxygen collisions are calculated by applying two center atomic state expansion method in the energy range of 0.1 to 300 keV. Slater type orbitals are used to represent the ground state wave function of oxygen atom, obtained from the model potential. Comparisons have been made with the existing theoretical findings as well as with the experimental data. The calculated values are found to be encouraging.

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000050   Bazboruah T;Boruah K;Boruah P K (Department of Electronics Science, Gauhati University, Guwahati-781 014) : Cosmic ray energy spectrum above 10<. Indian J Phys-Pt B 2000, 75(1), 5-10.

Gauhati University mini array of eight plastic scintillator of carpet area 2m² was operated since September 1996. The array detects giant Extensive Air Shower (EAS) by the method of time spread measurement of secondary particles. All the eight dectors were connected to a data acquisition system capable of recording arrival time spread of secondary particles upto 2.5 μS. Fast electronic circuits were employed to measure the density of shower particles as well as their arrival time spread with a resolution of 10 nS. Reanalyzed the data recorded by the array during September 1996 to April 1999. The reanalysis shows marked improvement in the slope of the energy spectrum above 10¹⁷ eV. The best fitted differential energy spectrum observed by the mini array is j(E)=10^25.38xE^-3.04±06m^-2sr^-1S ^-1eV^-1.

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000049   Banerjee P;Bose A;Mathur B S (Time and Frequency Section, National Physical Laboratory, , New Delhi-110 012) : Semi-empirical model to improve the accuracy of GPS time. Indian J Radio Space Phys 2001, 30(5), 243-8.

New generation of multichannel GPS receivers having a provision of a second pulse output is available. Presents an improved technique to get precise time with the help of such GPS receiver. This technique is based on semi-empirical model utilising the error in instantaneous position co-ordinates from the precise co-ordinates known in advance. The detailed experimental observations show a remarkable improvement in time jitter to about 50 ns from the jitter of 140 ns as observed by the normal technique. This method may also be used for real time applications.

000048   Bandyopathyay K;Bhattacharyya K;Bhattacharya A K (Department of Physics, Burdwan University, Burdwan-713 104) : The maximum entropy principle and Schrodinger eigenvalue problems. Indian J Phys-Pt B 2000, 75(1), 29-35.

Possibility of employing the maximum entropy principle, without any a priori knowledge of moments, to construct approximate density functions for bound, stationary quantum states has been explored. A viable scheme based on the fusion of the prescription provided by the above principle, with modifications as and when necessary, and the Rayleigh-Ritz variational approach has been put forward. Both ground and excited states of several problems in [∞, ∞] are considered. The extension to problems with finite boundaries has also been investigated. Pilot calculations involving various harmonic oscillators, the particle-in-a-box and its supersymmetric partner demonstrate the success of the endeavour beyond any soubt.

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000047   Awasthi A;Rastogi M;Gupta M;Shukla J P (Department of Physics, University of Lucknow, Lucknow-226 007) : Radio and microwave dielectric properties of PMA and PiBMA in solution. Indian J pure appl Phys 2000, 38(5), 319-23.

Dielectric absorption of dilute solutions of poly (methyl acrylate) (PMA) and poly (isobutyl methacrylate) (PiBMA) in benzene have been studied in the radio and microwave frequency region of 10 to 800 kHz and 10 GHz respectively and at five different temperatures 303, 313, 323, 328 and 333 K. Using frequency variation technique enthalpies of activation for PMA and PiBMA have been found to be 11.4 and 26.1 kJ/mol respectively. For both the systems, data evaluated using frequency variation method were also supported by the measurements carried out using concentration variation method at the microwave frequency. The enthalpies of activation ΔHε observed here were expected to be arising due to the internal rotation involving the ester group-C^"O_OR.

30 ref

000046   Ashok Kumar (Department of Physics, Tezpur University, Napaam-784 028) : Dependence of dopant ion selectivity on incorporation of proton in doped perovskite oxides. Indian J pure appl Phys 2001, 39(4), 263-6.

Proton conducitivity of doped perovskite metal oxides with ABO₃ structure (where A = Ca²⁺, Ba²⁺, Sr²⁺, B = Zr⁴⁺, Ce⁴⁺) aliovalently doped with lanthanide oxides (Yb₂O₃, Nd₂O₃ etc.) can be understood in terms of effective oxide ion vacancy concentration arising from dopant site selectivity and relative values of water incorporation energies. The conductivity results suggest that smaller lanthanide ions (Y³⁺, Yb³⁺) substitute for B site cations (Zr⁴⁺) generating oxide ion vacancies (V_o) necessary for proton incorporation as a result of charge compensation giving rise to enhanced proton conductivity. On the other hand larger lanthanide dopant ions (Nd³⁺, La³⁺) appear to substitute for A site cations (Sr²⁺) resulting in the generation of divalent cation vacancies. Such doping would suppress oxide ion vacancy concentration and the proton conductivity is decreased. The results are consistent with the energetics of substitution reactions.

23 ref

000045   Ansari M S;Mir G M (Regional Engineering College, , Srinagar-190 006) : On eigen values of simple harmonic motion. Indian J Phys-Pt B 2000, 75(1), 57-8.

In order to establish correspondence between Bohr's method of quantization and Schrodinger wave function approach, solved wave equation for simple harmonic oscillator, quartic potential and hydrogen atom with the assumption that the particle is totally confined within the classical limits. For certain values of the energy, the wave functions have maximum divergence at large distance from the classical turning points. Call such energy levels a Anti-eigen values. Anti-eigen values are also reported for harmonic and quatic potentials.

12 ref

000044   Angalkalinin D;SIngh G (Centre for Advanced Technology, , Indore-452 013) : Emittance measurements of microtron beam. Indian J pure appl Phys 2000, 38(5), 296-300.

Transverse beam emittance and twiss parameters of a 21 MeV classical microtron beam have been measured using nondestructive method. The beam profiles were recorded as a function of quardrupole strengths. A Gaussian curve is fitted in to the discrete points obtained from the secondary emission wire monitor. The beam ellipse parameters thus obtained have been used for deciding the beam optics of the transfer line which transports the beam from the microtron to the synchrotron. The results of the emittance measurements are discussed.

000043   Alfaz Uddin M;Islam F N;Shahjahan M;Choudhury M G M (Department of Physics, Rajashahi University, Rajshahi-6205, Bangladesh) : Semi-empirical formulae for electron impact ionization cross-sections. Indian J pure appl Phys 2001, 39(4), 205-12.

Semi-empirical formulae and BEB models are used to calculate the total cross-sections of single ionization of neutral atoms Mg, Al, Si, P, S by electron impact. The parameters of the semiempirical formulae are obtained by fitting the experimental data on the total cross-section of single ionization of the atoms by electron impact over the range of energy varying from the threshold to 200 eV. It is found that the semi-empirical models give qualititively as well as quantitatively good fits, while BEB model gives qualitative fits to the reference set of experimental data.

19 ref

000042   Acharya M;Dash G C;Singh L P (Department of Physics, College of Basic Science and Humanities, O.U.A.T, Bhubaneswar-751 003) : Hall effect with simultaneous thermal and mass diffusion on unsteady hydromagnetic flow near an accelerated vertical plate. Indian J Phys-Pt B 2000, 75(1), 37-47.

Effect of Hall current with simultaneous thermal and mass diffusion on unsteady laminar hydromagnetic viscous incompressible and electrically conducting fluid past a uniformly accelerated vertical porous plate (electrically non conducting) embedded in a uniform transverse magnetic field with heat source is investigated on the assumption of small magnetic Reynolds number. The results are discussed with respect to hydro magnetic parameter (Mt), Hall parameter (m), the buoyancy ratio parameter (N), Suction or injection parameter (a) Schmidt number (Sc) and heat source parameter (S) for Pr=0.71 with respect to air

18 ref

000041   Abd El-Daiem A (Physics Department, Faculty of Science(Sohag), South Valley University, Egypt) : Characteristics from Si<. Indian J pure appl Phys 2001, 39(4), 198-204.

Main experimental characteristics (multiplicity correlations) of secondary particles, angular distributions and forward-backward correlations have been investigated from Si²⁸ with emulsion at 4.5 GeV/c per nucleon have been investigated. The mean multiplicity ,n_s> is larger in Si²⁸ collisions with emulsion. The dependence of the average shower multiplicities on the heavy track and the black track multiplicities increases from Si²⁸. The cumulative effect can be a good candidate for the mechanism of production of some high energy backward emitted shower particles.

13 ref

022981   Council of Scientific & Industrial Research (NO, , c/o INSDOC, 14 Satsant Vihar Marg, New Delhi-110 067) : Device for excitation and detection of magnetic resonance using orthogonal transmitter probe coils. 0000, (NULL), (NULL).

022980   Rajendran A;Neelamegam p (PG and Applied Physics Res Dep, Nehru Memorial College, Puthanampatti, Tiruchirappalli, Tamil Nadu-621 007) : An instrument for measurement of dielectric constant of liquids using 8031 microcontroller. Bull Electrochem 2004, 20(2), 59-62.

A real time microcontroller based dielectric constant measurement setup has been developed to measure dielectric constant using a modified AC Desauty bridge network. This instrument system permits recording of dielectric constant at various concentration. A dedicated 8031 (8-bit) based Microcontroller board was employed for the hardware. The details of its interface to measure capacitance and compute dielectric constant have been explained.

4 illus, 6 ref