012028   Roy U;Ho Y K (Computer and System Sciences Dep, Siksha-Bhavan, Visva-Bharti, Santiniketan-731 235, Email: uroyin@yahoo.co.in) : Computation of doubly-excited 1s <. Indian J Phys 2008, 82(4), 387-401.

Presents here an implementation of the stabilization method to calculate the resonance energies and widths of the doubly-excited 1 s²3/3/'¹F° and 1s²3/3/'¹P° states of beryllium-like ions by calculating the density of resonance states. These systems have been treated formally as a two-electron problem by using a suitable model potential to describe the effect of the 1 s² core. Slater orbitals are used to represent the two electron wave functions. The results are compared with those available in the literature.

9 illus, 2 tables, 30 ref

012027   Phukan M;Sarma B K (Physics Dep, Gauhati Univ, Guwahati-781 014, Email: barinks16@yahoo.com) : X-ray and infrared spectroscopic studies of the molecular structure of 3-(2,4-dichlorophenyl)-1-phenylprop-2-en-1-one. Indian J Phys 2008, 82(6), 773-7.

The title compound C₁₅H₁₀Cl₂O is derived from acetophenone and 2,4-dichlorobenzaldehyde. There are two molecules in the asymmetric unit of the molecular structure of the compound. The two aromatic rings exhibit a non-coplanar geometry, which is due to the presence of two chlorine atoms in one aromatic ring. The compound was further characterized by infrared spectroscopy where a band at 1661 cm^-1 indicates the presence of the carbonyl group.

3 illus, 1 table, 9 ref

012026   Nomita Devi K;Nandakumar Sarma H;Sanjiv Kumar (Physics Dep, Manipur Univ, Canchipur, Imphal-795 003, Email: nomita_k@rediffmail.com) : Proton induced X-ray emission (PIXE) and proton induced γ-ray emission (PIGE) studies of some medicinal plants of north east India. Indian J Phys 2008, 82(6), 747-52.

Proton induced X-ray emission (PIXE) and proton induced γ-ray emission (PIGE) techniques were employed for the elemental analysis of twelve different plants traditionally used for medicinal purposes in north east India. PIXE is a well established ion beam analysis technique for the sensitive and non destructive determination of various elements having atomic number greater then eleven present in biological samples while PIGE offers a complementary method for the determination of light elements where the sensitivity of PIXE analysis is not quite adequate. When combined together, these analytical techniques provide concentrations of almost all elements present in the medicinal plants in quantities above ppm. Validity of the techniques was assured by analyzing certified plant reference materials (CRMs). A large number of trace elements like Mn, Fe, Cu, Zn, Rb, Sr, Na and Al are found to be present in the studied plants with variable proportions. K, Ca, Mg and P are quantified in percentage level while other elements are found to be present in parts per million levels. The results show that many of these plants contain elements of vital importance for human metabolism and prevention and healing of diseases.

1 illus, 1 table, 15 ref

012025   Krori K F;Dutta S;Das K (Theoretical Physics Dorum, , Lachitnagar, Bye Lane-7, Sub Lane -2, Guwahati-781 007, Email: kdkrori@rediffmail.com) : Direct derivation of sagnac effect. Indian J Phys 2008, 82(6), 665-72.

Rizzi and Ruggiero and later Ruggiero independently have shown that it is possible to calculate Sagnac effect in flat, Schwarzschild, Lense-Thirring (slowly spinning sphere), Kerr and Godel metrics in analogy with Aharonov-Bohm effect. One may reasonably wonder : Is it possible to derive this effect independently, i.e. by some direct method ? Shows that the answer to this question is indeed in the affirmative.

5 ref

012024   Krivit S B (NO, , 369-B, Third Street,556, San Rafael, CA-94901, USA, Email: steven1@newenergytimes.com) : Low energy nuclear reaction research - Global scenario. Curr Sci 2008, 94(7), 854-7.

Highlights of low energy nuclear reaction research, part of the field of condensed matter nuclear science. The field evolved from the so-called cold fusion discovery of two electrochemists, Martin Fleischmann and Stanley Pons at the University of Utah. Since the announcement of their discovery in 1989, more than 200 researchers in 13 nations have confirmed and expanded the set of experimental evidence that provides the validation for this new field of science.

^iia35 ref

012023   Konwar K;Gogoi P;Baishya B (Physics Dep, Dibrugarh Univ, Dibrugarh-786 004, Email: kanchankonwar@yahoomail.com) : Naphthacene and pentacene based organic thin film transistors with La₂O₃ as the gate insulator. Indian J Phys 2008, 82(6), 719-22.

Naphthacene and pentacene based metal-insulator-semiconductor organic thin film transistors (OTFTs) have been fabricated by the process of vacuum evaporation on glass substrates with La₂O₃ as the gate insulator. The calculated field effect mobilities of these devices are found to be comparable to those obtained by using SiO₂ as the gate insulator by others. The work demonstrates that the rare earth oxides are promising gate dielectric materials for OTFTs.

2 illus, 2 tables, 5 ref

012022   Kalita K (Physics Dep, Gauhati Univ, Guwahati-781 014, Email: ku_kalita@yahoo.com) : Interaction of loosely bound radioactive and stable nuclei via elastic scattering and fusion cross section. Indian J Phys 2008, 82(6), 801-5.

Elastic scattering angular distributions have been measured for ⁷Be+ ²⁷Al system at E_Lab=17,19, 21 MeV in the angular range θ_cm = 12-43°. An optical model (OM) analysis of these data have been carried out in order to extract OM potential parameters and reaction cross sections. One proton stripping cross sections were also measured at these energies. The fusion cross sections were deduced by subtracting the integrated transfer cross-sections from the reaction cross sections obtained from elastic scattering. The ⁷Li + ²⁷Al elastic scattering angular distributions were also measured at E_L=10,13,16, 19 and 24 MeV in the angular range θ_cm = 12 - 72° leading to the OM potential parameters. The α-evaporated spectra were also measured at θ_Lab = 52- 132°, compared with reproduced data with statistical model calculations and fusion cross sections were extracted from them. The Coupled channel fusion cross section including static nuclear deformations (CCDEF) calculations describe these data quite well. These data were compared with data on similar loosely bound systems and found to be consistent.

2 illus, 18 ref

012021   Jha B K;Mahto D;Thakur B;Singh K M;Jha G K (Physics Dep Univ, L.N.M.U., Darbhanga) : Thermodynamic properties of CD-based liquid alloys. Indian J Theor Phys 2007, 55(3), 215-23.

Studied the concentration dependent results on activity free energy of mixing short range order parameter and concentration fluctuations of Cd-based liquid alloys in the frame work of phase diagram. Here we have considered CdBi, CdMg, CdGa and CdHg liquid alloys for the calculation of various thermodynamic properties. The phase diagram has helped to understand the concentration dependent properties of mixing in terms of ordering energy and co-ordination number. Thus a link has been established between the microscopic properties and bulk properties of binary condensed matter liquid alloys. The results have been illustrated in the figures and tables.

5 illus, 2 tables, 12 ref

012020   Hazarika F B;Baruah G D (Physics Dep, Dibrugarh Univ, Dibrugarh-786 004, Email: gdbaruah@rediffmail.com) : Vector model of quantum interference laser. Indian J Phys 2008, 82(6), 761-6.

Reports a vector model of quantum interference laser in terms of phasor diagrams which involve the motion of organized vectors in terms of detuning. The time evolutions of these vectors have been worked out using different decay parameters in the usual expression for transition probabilities versus time in arbitrary units. The vector model of density matrix is used to describe inversion with reference to Poincare sphere.

5 illus, 14 ref

012019   Dutta P;Duorah K;Duorah H L (Physics Dep, Dimoria College, Khetri-782 403, Email: pratima_dutta2005@yahoo.com) : Nucleocosmochronology of dergaon meteorite. Indian J Phys 2008, 82(6), 673-8.

By considering relative abundance ratio of ⁴⁰K/⁴⁰Ar in Dergaon meteorite we have estimated age of the Dergaon meteorite as 2.12 Ga. The result obtained by P.N. Shukla et al by cosmogenic element is 4.7 Ga and they are found to be same order of magnitude.

3 illus, 2 tables, 4 ref

012018   Devi R;Kalita P K;Purkayastha P;Sarma B K (Physics Dep, Gauhati Univ, Guwahati-781 014, Email: kuhkhal@yahoo.com) : Synthesis and optical characterization of CdS nanocomposites. Indian J Phys 2008, 82(6), 707-13.

Nanocrystalline films are deposited in plastic substrates and particles in powder form are prepared by precipitation method from the same colloidal solution. The size and distribution of the crystallites are controlled by varying the temperature of the bath solution from 28°C to 90°C. The crystallite sizes are determined from X-ray diffraction and are found to be around 7 nm in films and 15 - 10 nm in powder. The band gaps are determined from the UV absorption spectra and are found to be within the range from 2.48 - 2.75eV in films and 2.48 - 2.64 eV in powder. Photoluminescence measurements shows enhancement of PL intensity for films at higher temperatures whereas excitonic emission at 376 nm and red shift around 603 nm is observed for precipitates.

5 illus, 1 table, 15 ref

012017   Deb S;Sarkar D (Physics Dep, Gauhati Univ, Guwahati-781 014, Email: sarkardeepali@rediffmail.com) : Fabrication of silver/cross-linked polyvinyl alcohol nanoparticles by hydrothermal method. Indian J Phys 2008, 82(6), 715-18.

Reports the fabrication of nanometer sized silver particles by simple hydrothermal method. Obtained nanoparticles are nearly spherical and have a narrow size distribution (20-30nm) as found in SEM pictures. The very strong plasmon resonance peak at 423-441 nm ranges in UV-Visible spectra is a consequence of the nano-sized Ag particles. XRD patterns show a characteristic peak for silver nanoparticles at 20 = 40°. FTIR spectra reveals the evidence of silver- PVA cross-linking. The I-V curve exhibits non-ohmic behaviour with maximum current 5.9 μ A at 20 V.

5 illus, 6 ref

012016   Das A;Saikia A (Physics Dep, Dibru Colleg, Dibrugarh-786 003, Email: abhijeet_das@yahoo.com) : Quark contribution in the evolution equation of the scaling violation of F₂. Indian J Phys 2008, 82(6), 789-94.

In a number of analyses in the literature, relations connecting the gluon density with the scaling violation of the structure function are reported. In all these approaches, the DGLAP equation for the gluon is considered after neglecting the quark term. In this work, we calculate the contribution coming from the quark term and estimate the error that enters when the quark contribution is neglected.

2 tables, 12 ref

012015   Chatterjee P;Kundu S K (Mathematics Dep, Siksha Bhavana, Visva Bharati, Santiniketan-731 235, Email: prasantachatterjee1@redffmail.com) : Large amplitude solitary waves in four component dusty plasma. Indian J Phys 2008, 82(4), 447-57.

Nonlinear dust acoustic waves are studied in a four component dusty plasma. The existence of soliton solution is determined by pseudo-potential approach. It is shown that in small amplitude approximation of the result reproduces the result obtained by Sayed and Mamun.

4 illus, 35 ref

012014   Charan R V K (Physics Dep, Gaya College, Gaya) : Scintillation counters in nuclear physics. Indian J Theor Phys 2007, 55(3), 237-44.

Different uses of scintillation counters in the experiments of nuclear physics has been presented here with relevant electronics diagrams and the curves.

6 illus, 7 ref

012013   Changmai R;Baruah G D (Physics Dep, D.H.S.K. College, Dibrugarh-786 001, Email: ranjan_changmai@rediffmail.com ) : Cavity-modified laser induced fluorescence of a blended system of polymer film. Indian J Phys 2008, 82(6), 679-83.

Laser induced fluorescence spectrum in the range 5600-6900Angustrum of a block of neat film of polymer blend system of Poly (1,4-Phenylene Vinylene) (PPV) and p-Benzoquinone (PBQ) has been obtained with the help of a 500 mW Ar⁺ (5145 Angustrum) laser. Drastic fluorescence quenching has been observed when this block of polymer blend system with a thickness of 2.5 mm, breadth 15 mm and length 15mm, is placed in an external cavity consisting of two dielectric mirrors separated by a distance of 20mm. Also observed substantial narrowing down of fluorescence in the higher wavelength side of the spectrum. Our measurement also allows us to shed light on the fundamental question of energy transfer and gain mechanism.

2 illus, 19 ref

012012   Chakraborty B;Pal R R (Physics and Technophysics Dep, Vidyasagar University, Midnapore-721 102, Email: radha_raman_pal@yahoo.com) : Novel high speed fully differential CMOS amplifier. Indian J Phys 2008, 82(4), 403-14.

Describes a high speed fully differential CMOS amplifier in which positive feedback is employed to improve the operating frequency. By this process the delay time reduces and the speed of operation increases. An even or odd number of stages can be cross coupled or directly coupled to form ring Voltage Controlled Oscillator or Current Controlled Oscillator (VCOICCO). An improvement of speed of around 167% was obtained from circuit simulation (using PSPICE). Here the typical supply voltage requirement is ±2 volt. Using this amplifier some applications are discussed.

8 illus, 20 ref

012011   Borthakur G G;Baishya B (Physics Dep, Dibrugarh University, Dibrugarh-786 004, Email: borthakur.gg@gmail.com) : Mixing dynamics and microscopic correlation of associated liquids. Indian J Phys 2008, 82(4), 459-65.

In the work outlines the role of time-dependent probability _ theory in explaining the mixing dynamics of two liquids, as an extension of work carried out by D Bertolini et al (1998) [1]. Exact form of microscopic correlation function and its relation to molecular structure and interaction are proposed.

2 ref

012010   Bordoloi N S;Choudhury D K (Physics Dep, Cotton College, Guwahati-781 002) : Form factors and charge radii of light and heavy flavoured mesons in a QCD inspired quark model with two loop static potential. Indian J Phys 2008, 82(6), 779-87.

Incorporates the effects of two loop static potential in the results of form factors and charge radii of both light and heavy flavoured pseudo scalar mesons in a QCD inspired quark model pursued by us. For heavy light mesons, we also report the results in the infinite heavy quark mass limit.

2 illus, 4 tables, 20 ref

012009   Borah S M;Pal A R;Bailung H;Chutia J (Plasma Physics Laboratory, Material Sciences Div, Institute of Advanced Study in Science & Technology (IASST), Vigyan Path, Paschim Boragaon, Gorchuk, Guwahati-781 035, Email: sankarmoni@gmail.com) : Hardness study of titanium nitride thin films deposited on bell-metal by cylindrical magnetron sputtering. Indian J Phys 2008, 82(6), 741-6.

Deposition of thin films by reactive magnetron sputtering is a very suitable method for the surface protection of materials. Titanium nitride thin film coatings provide very good protection to materials from wear and tear, corrosion, oxidation etc. Thin films of titanium nitride deposited by reactive magnetron sputtering in argon/nitrogen gaseous mixture acts as hard protective coating and also prevent the bell-metal substrate from reacting with the environment and getting oxidized. An investigation on the hardness of titanium nitride films deposited by reactive magnetron sputtering has been carried out by the method of nano-indentation and an analysis of the films for different deposition conditions is presented. The TIN film hardness is found to increase 13 times at 50% nitrogen in the gaseous mixture.

5 illus, 7 ref

012008   Bora K (Physics Dep, Gauhati Univ, Guwahati-781 014, Email: kalpana@gauhati.ac.in) : Type-II seesaw in SO(10) theories with spontaneous CP violation. Indian J Phys 2008, 82(6), 753-9.

Propose a possibility of spontaneous CP-violation (SCPV) at high scale in a SUSY SO(10) theory. The model is L-R symmetric SUSY SO(10) with 10 and 126 dimensional Higgs generating fermion masses, and the CP phase is generated through complex VEV of B-L breaking 126 Higgs. The model can have potential applications in explaining fermion masses, v masses via type-II seesaw mechanism, and Leptogenesis as well.

27 ref

012007   Bhattacharjee B;Debnath B;Sengupta S (Physics Dep, Gauhati Univ, Guwahati-781 014, Email: bb_22@rediffmail.com ) : Effect of collision geometry on the multiplicity of secondary charged particles emitted from <. Indian J Phys 2008, 82(6), 735-40.

The total charge of the projectile spectator fragments, Q_PF is taken as a measure of the degree of centrality of the collision thus defining the collision geometry. The mean multiplicities of different charged secondaries emitted in the interactions of ⁸⁴Kr-AgBr nuclei at 950 MeV/A have been investigated as a function of the total charge Q_PF of the projectile spectator fragments. It has been observed that the average number of produced particles decreases exponentially with the increase of Q_PF. In case of target associated fast particles, the average number is found to decrease linearly with the increase of Q_PF.

4 illus, 14 ref

012006   Bhadra J;Sarkar D (Physics Dep, Gauhati Univ, Guwahati-781 014, Email: sarkardeepali@rediffmail.com) : Field effect transistor from dispersion polymerized aniline. Indian J Phys 2008, 82(6), 795-9.

Reports here the fabrication of all polymer Polyaniline-Polyvinyl alcohol (PANI-PVA) FET and observation of FET characteristics. The FET is made in four different substrates, viz., Si, glass, PVA and transparent sheet. The I-V characteristics of these all polymers FET's, show clear FET behaviour for a p-channel semiconductor. The films are characterized by SEM and X-ray diffraction for morphology and structure study. The characteristics results give clear indication of formation of nanometer sized polyaniline spheres in PVA matrix.

3 illus, 17 ref

012005   Aggarwal R K;Negi P S;Satyawali P K (NO, Snow and Avalanche Study Establishment, Chandigarh-160 036) : New density-based thermal conductivity equation for snow. Def Sci J 2009, 59(2), 126-30.

More than two hundred thermal conductivity measurements tor different snow densities and snow types were carried out in-siiu at a field research station located in greater Himalayan range of India. These measurements were carried out using a commercially available portable thermal conductivity meter. Thermal conductivity measurements were carried out on the fresh snow, equi-lemperature snow, and surface hoar and temperature-gradient snow. Average thermal conductivity of snow varied from 0.08 W/mK (Fresh snow of 120 kg/m³ density) to 0.32 W/m K (Equi-temperature snow of 420 kg/m³ density). Based on these measurements, a new density-based thermal conductivity equation is proposed. Using this proposed equation, modeled snowpack temperatures showed closer agreement with the observed data as compared to the predictions based on other well-known empirical and theoretical thermal conductivity equations for snow. This study highlights the advantages and limitations of empirical based thermal conductivity equations over the complex models based on snow microstructure.

4 illus, 3 tables, 9 ref

012004   Abdelkhalek M M (Nuclear Physics Dep, Nuclear Reserch Centre, Atomic Energy Authority, Cairo, Egypt, 13759, Email: mohamed_moustafa_2000@yahoo.com) : Radiation and dissipation effect on unsteady MHD micropolar flow past an infinite vertical plate in porous medium with time dependent suction. Indian J Phys 2008, 82(4), 415-34.

Analysis is presented to study the effect of radiation on magnetohydrodynamic mixed convective unsteady laminar boundary layer flow of an optically thick electrically conducting viscous micropolar fluid past an infinite vertical plate. A uniform magnetic field is applied perpendicular to the plate. By taking the radiation heat flux in the differential form, and imposing an oscillatory time-dependent perturbation, the coupled nonlinear problem is solved for the angular velocity, temperature and velocity profiles. It is observed that, when the radiation parameter increases the velocity and temperature decrease in the boundary layer, whereas when Grashof number increases the velocity increases. As the magnetic parameter increases. the velocity and microrotation decrease. The magnetic field can be used effectively for controlling the rate of heat transfer as required in magnetohydrodynamic applications like MHD generators, nuclear reactors, where it is used to control enormous temperature. In comparison with the Newtonian fluid, the micropolar fluids have considerably different features from the Newtonian fluid in Nusselt numbers wall skin friction and wall couple stress.

16 illus, 2 tables, 28 ref

011014   Uddin M M;Hoque S M;Mahmud M S;Hakim M A; Chowdhury F U Z (Physics Dep, Chittagong University of Engineering & Technology (CUET), Chittagong-4349, Bangladesh, Email: mohi@cuet.ac.bd) : Effect of structural parameters on variation of microstructural and magnetic properties of nanocrystalline alloy of Fe_73.5Cu₁Nb₃Si_17.5B₅. Indian J pure appl Phys 2009, 47(4), 289-99.

Amorphous ribbons of Fe_73.5Cu₁Nb₃Si_17.5B₅ alloy have been annealed in the temperature range 475-700°C for X-ray diffraction (XRD) patterns. Crystallization induced by heat treatment resulted in the formation of a Fe-Si phase. The phase formed by primary crystallization has been found to be Fe-Si solid solution with a composition corresponding to disordered Fe-Si. Secondary crystallization of the Fe₃B and Fe₂B phases arises with the individual branches at the interfaces of the closely spaced crystals at the temperature 680°C, the spacing of such crystals was of the order of nanometer. Samples have been annealed in a controlled way in the temperature range 510-700°C with an interval of 10°C to 30°C for 1 h in order to study the effect of structural parameters of the nanocrystalline Fe(Si) grains on the variation of microstructural and soft magnetic properties. Temperature and frequency dependence of initial permeability of amorphous and devitrified toroid shaped samples have been measured. The permeability values showed little change as annealing time. Enrichment of Curie temperature has been observed for amorphous alloy due to the irreversible structural relaxation. The microstructures of the annealed samples are characterized as solid solutions of bcc Fe(Si) crystallites with grain sizes 5-19 nm and an abrupt increase 53 nm at 700°C. Silicon contents in the nanocrystalline phases determined from the lattice parameters are 12.67 to 15.48 At.%. The best magnetic properties have been observed when the annealing temperature is close to 575°C. Temperature dependence of real part of initial permeability of the annealed samples between the annealing temperature of 550°C and 575°C exhibits superparamagnetic/superferromagnetic behaviour at T >.

011013   Thirumaran S;Jayakumar J E (Physics Dep, D D E Annamalai University, Annamalainagar-608 002, Email: thiru_phymaran@yahoo.co.in) : Ultrasonic study of n-alkanols in toluene with nitrobenzene. Indian J pure appl Phys 2009, 47(4), 265-72.

The ultrasonic velocity, density and viscosity of the mixtures of the n-alkanols, namely, 1-propanol, 1-butanol, and 1-pentanol in toluene with nitrobenzene at 303 K have been measured. From the measured data of ultrasonic velocity, density and viscosity, some of the acoustical parameters such as adiabatic compressibility (b), free length (L_f), free volume (V_f) and internal pressure (p_I) have been measured. The excess values of the above parameters are also evaluated. The results have been analysed and interpreted in terms of molecular interactions such as dipole-dipole interaction through hydrogen bonding between nitrobenzene and 1-alkanols, and donor-acceptor complexity observed between toluene and nitro-benzene molecules.

011012   Sundaraganesan N;Joshua B D;Radjakoumar T (Physics (Engg.) Dep, Annamalai University, Annamalai Nagar-608 002, Email: sundaraganesan_n2003@yahoo.co.in) : Molecular structure and vibrational spectra of 2-chlorobenzoic acid by density functional theory and ab-initio Hartree-Fock calculations. Indian J pure appl Phys 2009, 47(4), 248-58.

The structure, harmonic frequencies and vibrational mode assignments for 2-chlorobenzoic acid (2CBA) monomer are calculated using HF and DFT methods employing the 6-311++G(d,p) basis set. The results of the molecular structure and vibrational frequencies obtained on the basis of calculations are presented and critically compared with the experimental IR data recorded in gas phase. The Raman and IR spectral data of 2-chlorobenzoic acid (2CBA) obtained in solid phase have also been included. The normal mode analysis has been carried out for all the modes. Most of the modes have wavenumbers in the expected range. The experimental spectra also coincide satisfactorily with those of theoretically constructed spectrograms.

011011   Srinivasan A;Pattanaik A K (Physics Dep, Indian Institute of Technology Guwahati, Guwahati-781 039, Email: asrini@iitg.ernet.in) : Fragility of Pb modified germanium chalcogenide glasses. Indian J Phys 2008, 82(5), 505-11.

Bulk chalcogenide glasses with compositions Pb_xGe_42-xSe₅₈(3 ≤ x≤ 15) (series I), Pb₂₀Ge_xSe_80-x (17 ≤ x≤24) (series II), Pb_xGe_42-xSe₄₈Te₁₀(3≤x<13 1> 15) (series III) and Pb₂₀Ge_xSe_70-xTe₁₀(17≤ x≤24) (series IV) were prepared by the melt quenching technique. The heat capacity jump at glass transition (ΔC_p ) and the activation energy for viscous flow ( E_n) of the four series of glasses were obtained from differential scanning calorimetry (DSC) studies. The composition dependence of ΔC_p and E_η of series I and III showed minima near the composition with x= 9 at. wt.% Pb. Similarly the ΔC_p and E_η data of series II and IV exhibited minimum near the composition with x = 21 at wt.% Ge. Since ΔC_p and E_η could be associated with the fragility of the glass network, the data obtained have been used to understand the changes occurring in the glass network as a function of composition. The results have also been discussed in the light of the majority charge carrier reversal occurring at the specific compositions in the respective series of glasses.

4 illus, 29 ref

011010   Soibam I;Phanjoubam S;Sharma H B;Sarma H N K (Physics Dep, Manipur Univ, Canchipur-795 003, Email: ibetombi_phys@rediffmail.com) : Synthesis of lithium zinc ferrite powders by citrate precursor gel formation method. Indian J Phys 2008, 82(5), 611-14.

A nitrate-citrate gel was prepared from metal nitrates and citric acid, inorder to synthesize lithium zinc ferrites. The nitrate-citrate gel so prepared exhibits self-propagating combustion behaviour. After combustion the synthesized powder is densified at a temperature of 900°C for 3 hours. In this method of synthesis, the sintering temperature is lower than that in ceramic process and calcination is not required.

2 illus, 5 ref

011009   Singh V;Sunil Krishna M V (Physics Dep, Indian Institute of Technology Roorkee, Roorkee-247 667, Email: virphfph@iitr.ernet.in) : Effect of temperature dependent rate coefficient of reaction N₂(A<. Indian J Radio Space Phys 2009, 38(2), 71-3.

The proton heating efficiency in polar thermosphere is revisited in the light of new findings of the temperature dependence of rate coefficient of the reaction N₂(A³Σ⁺_u ) + O. This reaction is considered as one of the most significant source of proton heating in auroral region. The present results show that the heating rate due to this reaction above 110 km is 1.4 to 2.3 times higher than the earlier results. The proton heating efficiency is found eight to ten percent higher than the earlier results in the peak energy deposition region (110-130 km). These results would be very useful in the study of heat budget in the polar thermosphere particularly during solar proton events.

011008   Singh R (NO, University of Oldenburg, Faculty V - Institute of Physics, Research Gr, P O Box 2503, 26111 Oldenburg, Germany) : Eighty years ago - the discovery of the Raman effect at the Indian association for the cultivation of science, Kolkata, India. Indian J Phys 2008, 82(8), 969-85.

In February 1928, Chandrasekhar Venkata Raman (1888-1970) and his student K S Krishnan (1892-1962) discovered an effect (later to be named as the Raman effect) at the Indian Association for the Cultivation of Science, Kolkatta. Nearly at the same time the effect was also observed by the Russian physicists Grigorii Samuilovich Landsberg (1890-1957) and Leonid Isaakovich Mandelstam (1879-1944). In the beginning the reception of the discovery in Germany was rather cold. In 1930 the Physics Nobel Prize was awarded to C V Raman alone. Why Krishnan and the Russian physicists were ignored by the Nobel Committee? The question has been answered with the documents (nominations letters and the reports) that were obtained from the Nobel Committee. Based on Krishnan's diary, his role in the discovery has been analysed. Evidences are given for the fact that the use of Mercury vapour lamp by Raman was a well thought step, and not per chance as stated by one of Raman's students.

4 illus, 1 table, 56 ref

011007   Sarmah K;Sarma R;Das H L (Physics Dep, Gauhati Univ, Guwahati-781 014, Email: ks_guphys@rediffmail.com) : Effect of wavelength and intensity of illumination on the phototoelectronic properties of CdSe thin films. Indian J Phys 2008, 82(5), 585-94.

Thermally evaporated CdSe thin films deposited under a vacuum environment of the order of 10^-5Torr, using high quality glass as substrate material, which are held at different elevated temperatures, are of polycrystalline nature having hexagonal structure whereas films grown at room temperature are amorphous. In gap type cell configuration of these films with thermally evaporated aluminium electrodes, the I-V characteristics are observed to be linear both under dark and under monochromatic illuminations of different intensities for low bias voltages, but such curves show Poole-Frenkel type of conductivity under the same illuminations for high bias voltages. In these cases the photocurrents, which are mainly controlled by different types of defects, vary widely with variation of intensities and wavelengths of light close to the threshold wavelength. The transport mechanism is generally not a single activated process and the traps have a very significant role in controlling the growth and decay of photocurrents.

8 illus, 2 tables, 19 ref

011006   Santra S B;Chanu S R (Physics Dep, Indian Institute of Technology Guwahati, Guwahati-781 039, Email: santra@iitg.ernet.in) : Numerical model for studing glass dissolution in water. Indian J Phys 2008, 82(5), 615-20.

Glass, a multicomponent vitreous system, can be considered as a random mixture of the constituent oxides. Due to random local environment, the binding energy of silica in the solid is expected to be randomly distributed. Dissolution of this random solid in water is modeled via a Monte Carlo (MC) algorithm. Time evolution of such a system under normal conditions shows that the system becomes rough to porous with the formation of dry silica gel layer. It is found that the chemical reaction of corrosion occurs at a constant speed in the steady state. As an effect, a self-established potential gradient is established and the system evolves into a critical state.

5 illus, 7 ref

011005   Salvi S V;Joshi V H (Material Physics Lab, Physics Dep, Birla College, Kalyan, Mumbai-421 304, Email: v_joshi1966@yahoo.com) : Effect of dopants on barium hexaferrite. Indian J pure appl Phys 2009, 47(4), 277-81.

Samples of Ba_1.266Ti_2.956 Fe_7.6Li_0.844O₁₉ hexaferrite have been prepared using anatase and rutile phases of TiO₂ by classical ceramic route. A pure sample of Ba Fe₁₂O₁₉ has also been prepared for comparison. The structural, electrical and magnetic characteristics have been studied by XRD, SEM, FTIR, two probe method, hysteresis loop and susceptibility curves. The samples exhibit hexagonal magnetoplumbic structure with spacegroup P6₃/mmc and p type ferrimagnetic behaviour. BaFe₁₂O₁₉ is a hard ferrite, however, the substituted hexaferrites are soft ferrites. The substitution causes increase in grain size and particle size. The Mc value, coercive force Hc, squareness M_R/M_s and Curie temperature T_c are large for rutile TiO₂ based samples as compared to anatase TiO₂ based samples. However, the anatase allotrope based samples enhance the grain growth. These materials can be used in the applications related to magnetic recording, microwave absorption and EM absorption.

011004   Saikia N;Tiru B;Handique D;Boruah P K;Boruah K (Physics Dep, Gauhati Univ, Guwahati-791 014, Email: nayan075@yahoo.co.in) : Programmable trigger circuit for UHE cosmic ray detection by mini-array method: simulation with VHDL. Indian J Phys 2008, 82(5), 627-37.

A trigger circuit (TC) to be used in the Mini Array Laboratory, Dept of Physics, Gauhati University is designed using VHDL. The Laboratory has been detecting Ultra High Energy Cosmic Ray (UHECR) Extensive Air Shower ( EAS) for the last 16 years. The working of the trigger circuit and its advantage over the already existing hardware is discussed in this paper.

5 illus, 1 table, 13 ref

011003   Saikia M;Devi M;Barbara A K;Sarmah H K (Physics Dep, Gauhati University, Guwahati, Assam-781014, Email: manojksaikia@gmail.com) : Raindrop size distribution profiling by laser distrometer and rain attenuation of centimeter radio waves. Indian J Radio Space Phys 2009, 38(2), 80-5.

Describes system design of laser distrometer, its calibration process and profiling of raindrop size distribution (RSD). Here, raindrop signature is extracted by allowing the drops to pass through a controlled field of view of a sensor. A laser beam works as signal source, phototransistor as detector-cum-amplifier and optical fibers as trans-receiving ports. RSD profiles and rain rate at different weather conditions have been presented. Specific raindrop attenuation of line of sight radio signals at 10 - 30 GHz of various drop diameters is then calculated by using standard attenuation equations and model values of scattering functions. Finally, the rain attenuation magnitudes are compared with those given by a model framed earlier [Timothy K I, Sharma S, Devi M & Barbara A K, Model for estimating rain attenuation in frequencies range 5-30 GHz, Electron Lett (UK), 31 (17) (1995)].

011002   Roy A (NO, Inter University Accelerator Centre, New Delhi-110 062, Email: roy@iuac.ernet.res.in) : Use of low energy accelerators. Indian J Phys 2008, 82(5), 497-504.

3 illus, 1 table, 14 ref

011001   Ram Prakash;Gupta D D;Singh M K (Physics Dep, Bipin Bihari (PG) College, Jhansi-284 001) : Role of VLF power line harmonic radiation in precipitating energetic electrons at high latitude. Indian J Radio Space Phys 2009, 38(2), 74-9.

A study is carried out on energetic electron precipitation at high latitude (L = 4.3) by VLF power line harmonic radiation. The life-time of energetic electrons interacting with coherent VLF line radiation has been found to be 5.56 days only. This indicates a significant precipitation of energetic electrons (energy ~ a few keV) at high latitudes (L=4.3). The average flux of precipitating electrons by VLF line radiation has been estimated to be 3.47x10^-3 ergs cm-2 s^-1 which is almost the same as caused due to coherent whistler-mode waves of 1 pT intensity at 5 kHz and is found to be consistent with energy flux deposited in the lower ionosphere at L ~ 2.4 caused by lightning induced precipitation [Inan et al., J Geophys Res (USA), 92 (1987) 3293].

011000   Nayak P K;Ravi S (Physics Dep, Indian Institute of Technology Guwahati, Guwahati-781 039, Email: sravi@iitg.ernet.in) : Critical current density from ac susceptibility measurments in (La_1-xY)₂BA₂CaCu₅O_z superconductors. Indian J Phys 2008, 82(5), 603-10.

Prepared a series of compounds (La_1-xY_x)₂Ba₂CaCu₅O_z for x = 0 to 0.5 by adding a CaCuO₂ layer to the parent compound La₂Ba₂Cu₄O_z and by doping Y in place of La. These materials are also prepared by adding 5 wt% of Ag to enhance the intergranular coupling and critical current density. X-ray diffraction measurements show that all the samples are essentially in single phase form and the patterns could be refined using P4/mmm space group in tetragonal cell. The typical lattice parameters are found to be a = b = 3.856 A, c = 11.576 A for x = 0.5 sample. Temperature variations of dc electrical resistivity measured on the above samples show that they exhibit superconductivity with T_c, ranging from 60 to 75 K. Temperature and ac field amplitude variation of ac susceptibility have been measured on the above samples. The field variation of ac susceptibility data has been analyzed by using Bean critical state model. Using both temperature and field variations of ac susceptibility data, the material dependent parameters, such as critical current density as a function of temperature and effective volume fraction of grains have been estimated. The Ag doped samples show relatively large critical current density compared to pure samples due to improved intergranular coupling.

5 illus, 1 table, 25 ref

010999   Nautiyal O P;Bhatt S C;Pant R P;Bourai A A; Singh P K;Saxena R;Semwal B S (Physics Dep, H N B Garhwal University, Srinagar, Uttarakhand-246 001, Email: nautiyal_omprakash@yahoo.co.in) : Preparation and characterization of ceramic samples of silver sodium niobate mixed system. Indian J pure appl Phys 2009, 47(4), 282-8.

Ceramic pellets of Ag_1-xNa_xNbO₃ (x = 0, 0.3, 0.5 and 0.7), system have been prepared by solid-state reaction method and sintering process. The prepared samples are characterized by XRD and SEM techniques. Lattice parameters and crystallite size have been calculated by XRD pattern and grain size has been calculated by SEM. It has been observed that all the prepared samples show orthorhombic structure at room temperature.

010998   Mukherjee M;Mukhopadhyay A;Chakraborty T (Physical Chemistry Dep, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700 032, Email: pctc@iacs.res.in) : Raman optical activity : a novel version of chiroptical spectroscopy. Indian J Phys 2008, 82(8), 987-1001.

Presents here an introductory review of Raman optical activity (RDA), a newly developed version of Raman spectroscopy suitable for predicting the absolute configuration of chiral molecules. The phenomenon involves minute differential scattering of the left and right circularly polarized lights from the chiral molecules, compared to the parent Raman scattering the RDA process is weaker by nearly three to five orders of magnitude. An operational theory of the phenomenon is presented with working equations. The connection between the experimentally observed quantities and the molecular parameters of interests is established. A brief description of the layout of the apparatus currently used for RDA measurements is presented along with a concise review of selected studies highlighting the possibilities of potential applications of this new version of chiroptical spectroscopy in the analysis of structural features of chiral molecules.

7 illus, 22 ref

010997   Meitei I A;Yugindro Singh K (Physics Dep, Manipur Univ, Canchipur, Imphal-795 003, Email: from_ablu@rediffmail.com) : Space distribution of QSOs. Indian J Phys 2008, 82(5), 519-22.

Study of the space density of the quasi-stellar objects (QSOs), expressed in the form of the optical luminosity function (OLF) and its cosmological evolution with redshift using over 9600 QSOs in the 10k catalogue of the 2dF QSO Redshift Survey (2QZ) of the Anglo-Australian Telescope (AAT) Two Degree Field (2dF).

4 illus, 2 ref

010996   Manhas P S;Pal K;Sharma S;Mangotra L K;Jamwal K K S (Physics & Electronics Dep, University of Jammu, Jammu-180 006) : New low-voltage class AB current conveyor II for analog applications. Indian J pure appl Phys 2009, 47(4), 306-9.

Current conveyors are unity gain active elements exhibiting high linearity, wide dynamic range and high frequency performance than their voltage mode counterparts. The new current conveyor operating at low-voltage supplies high input impedance and low output impedance and consumes less power. In this study, a new low-voltage class AB second generation current conveyor (AB CCII) is presented which can be easily converted into CFAs, etc. PSpice simulation results verifying theoretical analysis are also incorporated.

010995   Krori K D;Dutta S;Das K;Mahanta C R (NO, , Theoretical Physics Forum, Lachitnagar, Bye-Lane-7, Sub-lane-2,Guwahati-781 007, Email: kdkrori2rediffmail.com) : Raychaudhuri equation, big bang and accelerating universe. Indian J Phys 2008, 82(5), 531-7.

Shows that with appropriate inputs, the Raychaudhuri equation can provide physically rational clues to certain cosmological phenomena.

19 ref

010994   Gunasekaran S;Sailatha E (Spectro Physics Research Lab, Pachaiyappa's College, Chennai-600 030) : Vibrational analysis of pyrazinamide. Indian J pure appl Phys 2009, 47(4), 259-64.

Pyrazinamide (PZA) is an antitubercular drug, with molecular formula C₅H₅N₃O. The FTIR and FT Raman spectra of PZA have been recorded in the region 4000 - 400cm^-1 and 3500 - 50cm^-1, respectively for molecular study. A detailed vibrational analysis has been made on the fundamental modes of vibration. A normal coordinate analysis has been carried out for PZA following the Wilson's FG matrix method. A set of potential constants has been evaluated using the method of kinetic constants on the basis of C₁ point group symmetry. The evaluated potential constants have been compared with those of related molecules and are in the expected range to confirm the correctness of the assignments made. To check whether the chosen set of vibrational frequencies contributes maximum to the potential energy associated with the normal coordinates of the molecule, potential energy distribution (PED) has been evaluated.

010993   Gomati Devi T;Kumar K (NO, North-Eastern Regional Institute of Science and Technology (NERIST), Nirjuli-791 109, Email: devigomti2yahoo.co.in) : Solvent dependant Raman anisotropic bandwidth study in carbonyl containing molecule: role of van der waals volume in intermolecular interactions. Indian J Phys 2008, 82(5), 571-5.

The bandwidths of the anisotropic Raman component (Γ_aniso) of Ethyl Acetate (EA) were measured for different solvent concentrations (0) ranging from 10% to 90% using CH₃CN, CHCl₃ and C₆H₆ solvents and were plotted as a function of solvent concentrations. The data points are scattered and cannot be fitted into a particular curve. The data on anisotropic bandwidth are interpreted using the van der Waals' volume(V_w) within the framework of lineshape theory of Bratos and Tarjus. The ratio (Γ_aniso/V_w) has been estimated and plotted as a function of φ. This graph is an exponential curve in all the three solvents which shows that repulsive type of interaction forces e^-αR are responsible in the line broadening mechanism.

3 illus, 1 table, 19 ref

010992   Gogoi P;Konwar K;Baishya B (Physics Dep, Dibrugarh Univ, Dibrugarh-786 004, Email: paragiyoti_g@rediffmail.com) : Performance of thermally deposited polyerystalline Ge-thin film transistors with a copper interlayer fabricated on glass substrates. Indian J Phys 2008, 82(5), 577-83.

The performance of Ge- TFTs with a copper interlayer in the channel region is presented. TFTs are fabricated in staggered electrode structure on perfectly cleaned glass substrates using thermal evaporation process with rare earth oxide Dy₂O₃ as gate insulator. The TFTs are annealed at 370°C under high vacuum. The TFTs exhibit a mobility of 0.646 cm^{2V-1s-1and threshold voltage of 3 V. The characteristics and some electrical parameters of the TFTs with copper interlayer are evaluated using Weimer's model [Phys. Thin Films 2 149 (1964)] and characterized by Levinson et.al [J. Appl. Phys. 53 1193 (1982)] model. The various electrical parameters of the TFTs are compared with those of Ge - Dy₂O₃ TFTs fabricated without copper interlayer.}

5 illus, 2 tables, 11 ref

010991   Gogoi A;Ahmed G A (Optoelectronics and Photonics Laboratory, Physics Dep, Tezpur Univ, Tezpur-784 028, Email: ankurgogoi@gmail.com) : T-matrix approach for morphological characterization of spherical nanoparticles using laser. Indian J Phys 2008, 82(5), 567-70.

A laser based setup is designed to study the morphological characteristics of spherical PbS nanoparticles. Polarized light from a diode laser is detected, after getting scattered from nanosized particulate matter, by analyzer mounted photodiodes placed angularly. The signals from the detectors are interfaced to a high resolution data acquisition system. The size and shape characterization is attempted using the computational T-matrix approach. The investigation is aimed at accurate and in-situ measurement of stable and unstable nanoparticulate matter.

2 illus, 9 nref

010990   Devi O B;Singh C A (Physics Dep, Manipur Univ, Canchipur, Imphal-795 003, Email: amuchab@rediffmail.com) : Dirae and infeld-hull ladder operator methods for a modified oscillator potential. Indian J Phys 2008, 82(5), 551-60.

Dirac's method of solving the Schrodinger eigenvalue problem for the harmonic oscillator by constructing eigenvalue raising and lowering operators for a potential of the form V(x) = Ax² + Bx^-2 is reviewed. The eigenvalue problem of the potential is also solved by applying the Infeld and Hull's factorization method. In the process we construct the Infeld- Hull ladder operators which connect eigenvectors of a hierarchy of Hamiltonians. The laddering actions in the Dirac method and Infeld - Hull method are compared and constrasted.

1 illus, 12 ref