015184   Maiz F (IPEIN, , B P-62, Merazka 8000, Nabeul, Tunisia) : A simple method for the determination of the superlattices band structure: formulation and applications. Indian J Phys-Pt A 2004, 78(3), 309-13.

Assuming an approximated effectives mass and using Bastard's boundary conditions, introduce simplified method which allows the determination of the energy levels forming the sub-band structure of non-symmetrical, non-periodical potential samples. The energy quantification condition allows the determination of the energy levels for electron and hole. The wave functions are easily deduced as well as the energy transition. Applies this method to both theory and experimental data. The finding shows a good agreement with previous experimental and theoretical results. The method is useful for any number of semiconductor layers arranged in any random way; thus making it more realistic, simpler and applicable to superlattice analysis and device designs.

4 illus, 7 tables, 22 ref

015183   Krishnakumar V;Balachandran V (Post-graduate Dep Appl Phys, Nehru Memorial Coll, Puthanampatti-621 007, Tiruchirappalli) : FTIR, FT-Raman spectral analysis and normal coordinate calculations of 2-hydroxy-3-methoxybenzaldehyde thiosemicarbozone. Indian J pure appl Phys 2004, 42(5), 313-18.

The normal coordinate analysis of 2-hydroxy-3-methoxybenzaladehyde thiosemicarbozone has been carried out by using a modified Urey-Bradley Force Field. The calculated frequencies were obtained by considering the interaction between non neighboring stretching and bending vibrations and by introducing an appropriate set of internal coordinates in the course of calculations. All the functional modes of vibrations are assigned and discussed in detail.

2 illus, 2 tables, 15 ref

015182   Kandpal D;Singh K Y;Gupta B R K (Phys Dep, G B Pant Univ of Agric an dTechnol, Pantnagar-263 145) : On pressure dependence of the relative compression (V/V_o) at room temperature for solids: copper and lead as prototypes. Indian J Phys-Pt A 2004, 78(3), 393-5.

A correction term has been introduced in the usual Tait's equation of state (EOS) and then used to predict the pressure dependence of the thermal compression for the solids: copper (Cu) and lead (Pb). The predictive capabilities of the complete EOS are discussed. The results obtained from the modified Usual Tait's equation of state are found closer to the available experimental data as compared to those values achieved without taking into account the correction factor in the original Tait's equation of state.

2 illus, 2 tables, 20 ref

015181   Joshi D C;Gupta A P;Singh S (Phys Dep, M B Govt P G College, Haldwani-263 141) : Pressure-volume-temperature (P-V-T) relationship for NaCl crystal. Indian J pure appl Phys 2004, 42(5), 347-50.

A method for determining the compression data (VV_o) at simultaneously elevated temperature and pressure up to a pressure of 35 kbar a temperature of 773K has been developed. This method is based on the Chopelas Boehler approximation for variation of the Anderson-Grunejsen parameter δ_T with the change in compression. The calculated values are found to be in good agreement with the experimental data.

3 tables, 14 ref

015180   Govinda Bhat S;Dharmaprakash S M (Phys Dep, Mangalore Univ, Mangalagangotri-547 199) : Optical characteristics of bismuth thiourea chloride single crystals. Indian J Phys-Pt A 2004, 78(3), 385-7.

Bismuth thiourea chloride single crystals with molecular formula Bi [Cs (NH₂)₂ Cl₃ (BTC) have been grown in gels at ambient temperature and characterized by optical techniques. Refractive indices along different crystal axes were determined for different wavelenths of visible light. BTC crystals are optically negative and uniaxial. The optical absorption characteristics of BTC have been measured in the wavelength range 200nm-1400nm. Optical second harmonic generation (SHG) of Nd:YAG laser (F128><108>=1064nm) has been observed in BTC single crystal.

4 illus, 8 ref

015179   Govind;Joshi S K (Theory Group, National Physical Laboratory, , Dr K S Krishnan Marg, New Delhi-110 012) : Spintronics and quantum computation. Indian J Phys-Pt A 2004, 78(3), 299-308.

An effort has been made to discuss a new class of devices based on electron spin. Several proposed spintronic devices have been studied which can help in providing new functions and an improvement over the existing electronic devices.

4 illus, 100 ref

015178   Giri D K;Gupta P S (Applied Phys Dep, Indian Sch of Mines, Dhanbad-826 004) : Higher-order squeezing in Raman scattering. Indian J pure appl Phys 2003, 41(12), 946-9.

The occurrence of fourth and fifth-order squeezing in the fundamental mode of the electromagnetic field in spontaneous Raman process under the short-time approximation is investigated based on a fully quantum mechanical approach. The coupled Heisenberg equations of motion involving real and imaginary prts of the quadrature operators are established. The dependence of the higher-order squeezing on the number of photones in investigated. It is shown that higher-order sequeezing allows a much larger fractional noise reduction.

2 illus, 18 ref

015177   Ghosh D;Deb A;Ghosh P;Ahmed S I (Nuclear and Particle Phys Res Centre, Phys Dep, Jadavpur Univ, Kolkata-700 032) : Evidence of intermittent fluctuations and multifractality of target residues in lepton-nucleus interactions at (420±45) GeV. Indian J Phys-Pt A 2004, 78(3), 363-6.

Analysis of target fragments of muon-nucleus interactions data at (420±45) GeV in terms of Scaled Factorial Moments (SFMs) in one dimension azimuthal angle phase space is reported. The SFMs are found to increase with decreasing bin width of the azimuthal phase space of the target fragments. The strength of the intermittency increases with the order of the moment. Thus this analysis reveals intermittent fluctuations as well as multifractality of target fragments.

2 illus, 16 ref

015176   Ghosh D;Deb A;Dutta D;Sarkar R;Dutta I;Mondal M (Nuclear and Particle Physics Res Centre, Phys Dep, Jadavpur Univ, Kolkata-700 032) : Multifractality and multifractal specific heat in fragmentation process in <. Indian J Phys-Pt A 2004, 78(3), 359-62.

Investigates the multifractality of target fragments of ²⁴Mg-AgBr interaction at low energy (4.5AGeV) using a new method as proposed by Takagi. The analysis involes the step of measuring the generalised dimension D_q which in turn, deduce the multifractal behaviour of target fragments. Ultimately determines multifractal specific heat. A comparison with other data is also done.

3 illus, 2 tables, 15 ref

015175   Ghosh D;Deb A;Bandyopadhyay P;Mondal M;Lahiri M;Patra K K (Nuclear and Particle Phys Res Centre, Phys Dep, Jadavpur Univ, Kolkata-700 032) : Pion fluctuation study in π<. Indian J Phys-Pt A 2004, 78(3), 353-7.

Fluctuations in pseudorapidity distribution of secondary particles in π^--AgBr interactions at 350 GeV/c are analysed using F_q moments, G_q moments and T_q

6 illus, 17 ref

015174   Durai S;Ramadoss P (P G and Res Dep of Phys, A M Jain College, Chennai-600 114) : Optical refractive index from ultransonic velocity in binary liquid mixtures. Indian J pure appl Phys 2004, 42(5), 334-7.

A new empirical relation connecting the optical refractive index and the ultransonic velocity has been tried in the case of solutions (Durai S & Ramadoss P, Acta Acostica, 89(2003) 173). The same is extented to four binary liquid mixture systems, making use of the experimental data available. The results are satisfactory. Jacobson's free length (L_f) and mean free path (λ) play significant roles. Further Debye temperature a property of solid like behaviour of liquids is calculated for the systems and the results are analyzed.

4 tables, 18 ref

015173   Das S K;Sengupta S (Phys Dep, Maulana Azad Coll, 8 Rafi Ahmed Kidwai Rd, Calcutta-700 013) : Extensivity of entropy. Indian J pure appl Phys 2003, 41(12), 941-5.

In the conventional framework of thermodynamics it is an established fact that, in absence of surface effects, infinitesimal change in entropy is extensive. But this does not automatically guarantee the extensivity of entropy. Discusses this problem, strictly within the framework of thermodynamics, using a principle of linear superposition in conjunction with a simple postulate, which contains a feature consistent with quanum mechanical concept of indistinguishability of atoms and molecules. Some important consequences of the extensivity of entropy are also discussed. Extensivity of entropy is essential to calculate the change in entropy in an adiabatic irreversible process where the number of atoms of a system is not fixed as well as to make thermodynamics free from the well-known Gibbs paradox.

3 illus, 9 ref

015172   Chhantbar M C;Trivedi U N;Tanna P V;Shah H J; Vara R P;Joshi H H;Modi K B (Physics Dep, Saurashtra Univ, Rajkot-360 005) : Infrared spectral studies of zn-substituted CuFeCrO₄ spinel ferrite system. Indian J Phys-Pt A 2004, 78(3), 321-6.

The spinel solid solution series Zn_x Cu_1-x FeCrO₄ with x = 0.0, 0.2, 0.4 and 0.6 has been studied by infrared absorption spectroscopy. The IR-spectrum showed two main absorption bands V₁ and V_{2-1 arising from from tetrahedral (A) and octahedral (B) interstitial sites in the spinel lattice. The absence of V4 band suggests that lattice vibrations are insignificant. No shoulder or splitting is observed around V1 and V2 bands confirming absence of Fe⁺ ions in the system. The sharpening of band with Zn-content (x) is due to the fact that the system changes from inverse to normal spinel structure. The structural and optical properties are correlated and the bulk modulus, compressional and shear velocity values determined through IR spectral analysis are in good agreement to those obtained through ultrasonic pulse transmission technique.}

6 illus, 3 tables, 34 ref

015171   Chavan N V;Motke S F;Kulkarni S K;Khedkar C D (Adarsha Edu Cation Society's Coll, , Hingoli-431 513) : Nitrogen adsorption studies of cataphoretically deposited lanthanum hexaboride on tantalum. Appl Sci Period 2004, 6(1), 6-14.

The interaction of nitrogen with laB₆ at different temperature is studied. Simple adsorption is observed. The static substrate model is used. Compound formation of boron or lanthanum with nitrogen is not found. The variation of Δϕ with increasing nitrogen exposure on LaB₆ at different temperature shows oscillatory nature. Incorporation of N₂ on LaB₆ is seen. Cataphoretically deposited lanthanum hexaboride on tantalum is found to be suitable material for the cathode.

10 illus, 5 ref

015170   Chander S;Srivastava B K;Krishnamurthy A (Phys Dep, Univ of Rajasthan, Jaipur-302 004) : Magnetic behaviour of nano-particles of Ni_0.5Co_0.5Fe₂O₄ prepared using two different routes. Indian J pure appl Phys 2004, 42(5), 366-70.

Literature reports on bulk sample fo the ferrite Ni_0.5Co_0.5Fe₂O₄ confirm a complete inverse spinel structure. On site occupancy and magnetic anisotropy on nano-particle samples of the titled ferrite prepared using two different routes - a wet chemical co-precipitation process and sol-gel method have been studied. Estimated average particle sizes of the two samples (referred of as NCWET and NCSOL) are ~ 75Å and ~ 190Å respectively. Small angle neutron scattering measurements made on the fluid sample comprising the sample prepared by wet chemical process gies median size ~ 77Å with standard deviation μ = 0.60. Mossbauer studies at 300K show that the two ferrite samples maintain inverse spinel structure even in nanocrystalline state. Magnetization and Mossbauer measurements show that part of the sample in both the cases is in superparamagnetic state. Magnetic anisotropy is larger in the nano-particle state and surface spin disorder also contributes to this.

8 illus, 1 table, 6 ref

015169   Burghate D K;Deshmukh S H;Akhare V P;Joshi L; Deogaonkar V S (P G Dep of Phys, Shri Shivaji Sci Coll, Amravati-444 603) : Study of electrical conduction mechanism of succinic acid doped glycine pellet. Indian J Phys-Pt A 2004, 78(3), 331-5.

The electrical conductivity of succinic acid doped glycine pellet has been measured by studying the I-V characteristics at various temperatures in the range 313K-353K. The results are presented in the form of I-V characteristics and analysis has been made by interpretation of Poole-Frenke, Fowler-Nordheim, Schottky, log(J) versus T plots, Richardson and Arrehenius plots. It is observed that the conduction mechanism in the present case is a cooperative process, with Poole-Frankel type in low field range and Fowler-Nordheim mechanism in high field range.

8 illus, 1 table, 20 ref

015168   Banerjee P K;Sengupta A (Radio and Atmospheric Sci Div, National Physical Lab, New Delhi-110 012) : Doppler technique for detection of victims buried under earthquake rubble. Indian J pure appl Phys 2003, 41(12), 970-4.

Design and development of an electronic remote victim locator is described. It has been designed for locating remotely, any animate subject buried under rubble or behind a barrier. It works on the principle of Doppler effect at microwave frequencies. Electromagnetic signal travels down the debris from a transmit/receive antenna, illuminates the animate subject under the rubble and returns to the top of the debris having phase modulated with body movements. The antenna picks up the phase-modulated signal, which is processed by a microwave phase synchronous receiver. The detected signal is displayed on an oscilloscope or any other suitable display device. The display is either a regular breathing cycle or any sudden shift in its steady level, resulting from even a slight movement of any part of the body. An important part of the system is the clutter (unwanted reflections) cancerller. Presently, the system can penetrate a dry concrete debris depth of the about 2 m. Detection depth may be greater if there are more air voids in the debris. Efforts are on to improve the depth of penetrtion in the rubble. The same system can detect presence of any person behind a barrier, which has security applications.

3 illus, 6 ref

015167   Ali A;Nain A K;Chand D;Bhajan Lal (Chem Dep, Jamia Millia Islamia (Central Univ), Jamia Nagar, New Delhi-110 025) : Volumetric and viscometric studies on N,N-dimethylacatamide + 1-hexanol/1-heptanol binary liquid mixtures at different temperatures. Indian J pure appl Phys 2003, 41(12), 928-35.

Densities ρ, and viscosities η, have been measured for pure N,N-dimethylacetamide (DMA), 1-hexanol, 1-heptanol and for their 18 binary mixtures with DMA as a common component, covering the entire composition range, at 25, 30, 35, 40 and 45°C. Using the experimental values of ρ and η, the excess molar volume V^E, excess viscosity η^E, excess rheochore [R^e], excess partial molar voluem V₂°^E, of alkanols in DMA at infinite dilution and excess free energy of activation of viscous flow ΔG^*E, have been calculated. The dependence of these excess functions on composition and temperature has been discussed from the point of view of inter-molecular interactions in these mixtures. Furthermore, from the temperature dependence of viscosity, the enthalpy ΔH^*, and entropy ΔS^*, of activation of viscous flow have also been calculated and their dependence on composition have been discussed..

5 illus, 3 tables, 29 ref

015166   Al-Mamun;Firoz S H;Islam A B M O (Phys Dep, Univ of Dhaka, Dhaka-1000, Bangaladesh) : Detection of crystal structure of chemically-deposited copper selenide thin films. Indian J Phys-Pt A 2004, 78(3), 377-9.

3 illus, 2 tables, 13 ref

015165   Al Bayati A A (Phys Dep, College of Sci, Univ of Baghdad, Baghdad, Iraq) : Effect of additive materials to concrete on Y-ray absorption coefficient. Indian J Phys-Pt A 2004, 78(3), 405-07.

Gamma-ray absorption coefficient in some shielding materials, such as, iron, brass, lead and concrete, is measured experimentally in the study using a Cs-137 source of energy 0.662 Mev. Two types of concrete samples are used, ordinary concrete and concrete with additive fractional weights of iron or brass or lead materials. Experimental measurements are carried out for single-layer absorbers. The dependence of gamma-ray absorption coefficient on the atomic number, and density of the absorber material is taken into account. The results showed that for concrete, the value of gamma-ray absorption coefficient can be increased in a material of high atomic number ( or density) is added to it.

2 tables, 19 ref

015164   Aggarwal a K;Kaura S K;Chhachhia D P;Sharma A K (Coherent Optics Div, Central Sci Inst Organ, Sector 30, Chandigarh-160 030) : Realization of holographic optics based interferometer for study of phase objects. Indian J pure appl Phys 2004, 42(5), 326-33.

Describes different configurations for realization of a simple, compact and robust holographic optics based interferometer, which makes use of minimal bulk optical components. the optical arrangements in the proposed interferometer set-ups involve a very simple alignment procedure and conventional holgraphic recording material is used in the formation of holographic optical elements. Recording schemes for the formation of holgraphic optical elements and the related techniques for the realisation of three different interferometer set-ups along-with the experimental results have been presented. The proposed interferometer set-ups are quite suitable for performing optical test studies on phase (transparent) objects in real time.

12 illus, 18 ref

014304   Yadav R;Singh A K;Srivastava O N (Department of Physics, Banaras Hindu University, Banaras-221 005) : On the formation and characterization silver nanoparticles, nanothreads and nanorods by electrical arc evaporation. Indian J Phys-Pt A 2004, 78(1), 85-7.

Reports the formation and characterization of silver nanoparticles, and nanorods. Those nanoversions were obtained by electrical are evaporation of silver electrodes under helium abience with varying pressures. Electrical arc evapuration was done by using <95>10 V and (<95>50-100 amp) D.C. current. The evaporated materials were deposited on cathode and formvar coated copper grid mounted on a liquid N2 cooled speciment holder Transmission electron Microscopy was employed to characterize the condensed materials. These investigations revealed that the condensed materials consisted of nanoparticles and nanothreads on the grid and nanorods on the cathode. The silver nanoparticles have been found to grow under helium pressure of 50 to <95>150torr. The silver nanothreads and nanorods, on the other hand, have been formed under helium pressure of <95> torr. Extensive electron microscopic investigations showed that the size of the nanoparticles was found to vary between <95> 150 nm to <95> 10nm. The nanorods have diameters varying from 40 nm to 80 nm and length between 1 μm to 3μm.

3 illus, 22 ref

014303   Upreti U C (National Physical laboratory, , Dr K S Krishnan Road, New Delhi-110 012) : Zn content variation effect on excess conductivity, superconducting order parameter dimensionality and interlayer coupling in ErBa₂Cu_3-xZn_xO_7-δ. Indian J pure appl Phys 2004, 42(3), 195-200.

Zn concentration variation effects on superconducting order parameter fluctuations are compared in ErBa₂Cu_3-xZn_xO_7-δ polycrystalline bulk samples for x=0.0, 0.03, 0.05, 0.12 and 0.18; perhaps as a first ever study. The SCOPF in pure and Zn doped samples are 3D. Zn seems to cause suppression of 2D fluctuations. SCOPF dimensionality shows independence from carrier concentration variation due to Zn in the planes and also suggests strong coupling between two nearest CuO₂ planes in the unit cells in pure and Zn doped samples. Fluctuations remain almost invariant to Zn doping vis-a-vis the pure sample.

2 illus, 1 table, 42 ref

014302   Suresh K;Gopalan R;Singh A k;Muraleedharan K; Sridhara Rao D V;Chandrasekaran V (NO, Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad-500 058) : Studies on Sm(Co_0.9-xFexCu0.1)4.8 nano composite magnetic powder. Indian J Phys-Pt A 2004, 78(1), 115-19.

Nanocomposite Sm(Co0.9-xFexCu0.1)4.8 ( x = 0 and 0.1) alloy powder, prepared by mechanical milling has been characterised using X-ray diffraction (XRD), differential scanning calorimeter (DSC, transmission electron microscopy (TEX) and vibrating sample magnetometer (VSM). XRD studies revealed that the alloys are partly amorphous after 72 h milling. The particle size measured from XRD and TEM studies is found to be in the range 10-70 nm and this size is below the single domain particle size (<95> 100 nm) of most of the highly anisotropic rare earth magent materials. Upon annealing at 923 K and 973 K, magnetic measurements exhibited the evidence of exachange coupling between the magnetic phases in Sm(Co0.8Fe0.1Cu0.1)4.8 alloy.

11 illus, 18 ref

014301   Srinivasan R;Narayanan A (NO, Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore 560 080) : Condensation of bound pairs of fermionic atoms. Curr Sci 2004, 86(10), 1356-62.

6 illus, 15 ref

014300   Singh V R;Palwimder Kaur (Instrumentation and Sensors Group, National Physical Laboratory, , New Delhi-110 012) : Surface morphology of gall bladder stones. Indian J pure appl Phys 2004, 42(3), 189-94.

Gall bladder stones are crystalline structures formed by concretion or accretion of normal or abnormal bile constituents. These stones are normally made of cholesterol, calcium, phosphate, carbonate and proteins. The aetiology of gall bladder stones is multifactoral. Scanning electron microscopy (SEM is used to investigate the surface features of the mechanically fractured part of the stone samples. Micrographs exhibit a non uniform polycrystalline surface without specific grain boundaries with porosity, leading to loose bounding of crystals and hence low specific gravity. These results pertaining to surface characterisation are very useful for understanding the disintegration process of stones inside or outside the human body.

6 illus, 2 tables, 14 ref

014299   Singh V A;Pandey R K;Harbola M K (Department of Physics, Indian Institute of Technology, Kanpur, Kanpur-208 016) : To sacle or not to scale : self capacitance, "Hubbard U" and quantum dot size ?. Indian J Phys-Pt A 2004, 78(1), 61-5.

A seminal question to ask regarding quantum dots is how(if at all) its self-capacitance scales with size. What kind of a phenomenology should guide physicists who are involved in studying Coloumb blockage effects and in the practical task of evolving single electron transistors? Answering these issues involves calculating many body effects in quantum dots. Electron-electron interaction within a simplified spherical quantum dot was studied using the local density approximation (LDA) and local spin density approximation (LSDA). Experiment with a variety of confining potentials (trinagular, harmonic, square well etc.) and with a varying unmber of electrons (N = 2 to 20). Detailed study was carried out for scaling behaviour of the "Hubbard U", which is a measure of the capacitive energy, with quantum dot size R(U <95> / R^β). It was found that the scaling exponent β is approximately 1/2 for harmonic confinement and equal to l for the square well confinement. "Hubbard U" depends critically on the shape of the confining potential chosen and size of the quantum dot. It exhibits a weak dependence on the number of electrons. Also examines the relative importance of Coulomb, exchange and correlation terms in the "Hubbard U" and found that correlation plays a relatively more important role at large size.

3 illus, 1 table, 24 ref

014298   Singh P;Babbar V K;Razdan A;Goel T C; Srivastava S L (Physics Dep, Indian Institute of Technology Delhi, New Delhi) : Magnetic, dielectric ad microwave absorption studies of Ba-CoTi hexaferrite - epoxy composites. Indian J pure appl Phys 2004, 42(3), 221-8.

The microwave absorption, complex permittivity and complex permeability studies of hexaferrite composites prepared with Ba(CoTi)_xFe_12-2xO₁₉ wherein x varies from 0.0 to 1.0 in steps of 0.2 were made in frequency range from 8.0 to 12.4 GHz. The effect of Co²⁺Ti⁴⁺ substitution and of microstructural variation on complex permeability, permittivity and microwave absorption have been analysed. The hexaferrite-composite with x <62> 0.0 exhibit significant dispersion in the complex permittivity (ε_t^" - jε_t^") with maximum value of ε_t^" is observed from x equal to 1.0. The dispersion in complex permeability (μ,^'-jμ_t^") is not significant and is attributed to the shielding effect of polymer matrix over the ferrite crystallites and to the low alternating electromagnetic field applied to the sample. The variation of reflection loss has been studied as a function of frequency (ƒ), Co²⁺Ti⁴⁺ content and thickness of te absorber. A maximum absorption of 16 dB (86<62>) is obtained for composites with x equal to 0.4 and of 2.8 mm thickness.

4 illus, 22 ref

014297   Singh G S;Bajpai R P (Advanced Optical Processing Division, Central Scientific Instruments Organization, Sector 30, Chandigarh - 160030) : Determination of kinematics of four component electronically compensted zoom lenses. J Optics 2003, 32(3), 129-44.

A simple method developed to solve the problem of kinematics determination of four-component electronically compensated zoom lenses is described. It has been shown that a simple paraxial conjugate equation, along with magnificaition equation can be used successfully to solve the complex problem of component displacement in a four-component electronically compensated zoom lens. This method provides a deep insight into the image formation process by a zoom lens. The method developed is simple to program and provide excellent informaition about working of four-component electronically compensated zoom lenses.

3illus,8 tables,8 ref

014296   Shukla R P;Udupa D V;Das N C;Mantravadi M V (Spectroscopy Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085) : Large shear plate interferometer. J Optics 2003, 32(3), 119-27.

The design and fabrication of a large shear plate is presented to obtain a large shear. The shear plate consists of two glass plates separated with a large air gap. The two glass plates are held rigidly with three spacer rods. The inner surfaces of the glass plates are made nearly parallel to each other. The shear is obtained after reflection from the two inner surfaces. A shear plate assembly of diameter 200 mm has been built to obtain a maximum shear of 50 mm. This shear plate assembly is found to be useful for testing lenses and for checking the laser beam collimation of an aperture 100 mm with a higher sensitivity.

10 illus, 11 ref

014295   Senapati S;Mandal D;Ahmad A;Khan M;Sastry m; Rajiv Kumar (Catalysis Division, National Chemical Laboratory, Pune 411 008) : Fungus mediated syntheis of silver nanoparticles : a novel biological approach. Indian J Phys-Pt A 2004, 78(1), 101-5.

A novel biological method for the intra- and extracellular synthesis of silver nanoparticles using the fungi, Verticillium and Fusarium oxysporum respectively has been demonstrated. Exposure of the Verticillium sp. fungal biomass to aqueous AgNO3 solution resulted in the intracellular reduction of the Ag⁺ ions and formation of silver nanoparticles of dimentions 25 ± 8 nm. Electron microscopic analysis of thin sections of the fungal cells indicated that the silver nanoparticles were formed below the cell wall surface, possibly due to reduction of the metal ions by the enzyme present in the cell wall membrane. In the case of Fusarium oxysporum, exposure of the biomass resulted in the extracellular silver nanoparticles of dimensions 5-50 nm. this opens up an exciting possibility of a microorganism based nanoparticle synthesis strategy wherein the nanoparticles may be entrapped in the biomass in the form of a film or produced in solution, both having interesting commercial potential.

5 illus, 34 ref

014294   Saha H;Hossain S M;Das J (IC Design and Fabrication Centre, Department of Electronics and Teleco, Jadavpur University, Kolkata-700 032) : Porous silicon : a natural nano structure for sensing and photonic applications. Indian J Phys-Pt A 2004, 78(1), 19-25.

Porous silicon (PS) is emerging as an important nanocrystalline material that can be formed and controlled suitably for application as gas and vapour sensors, as well as, as LEDs and photonic crystals. Results of in-depth investigations on the role of formation parmeters on porosity, layer thickness and the extgent of non-directional pore growth in PS have been reported. Measurements like SEM and AFM techniques, photoluminescence and XRD studies, have been performed to get the dimensions of Si-nano-crystallites and pores. IR absorption spectra have been employed to identity the chemical species in as-grown and aged PS layer. The luminescence property of PS has been used to fabricate a 7-segment display. A theoratical model for vapour sensing in nano-porous medium has been outlined and implemented in porous silicon vapour sensor.

16 illus, 2 table, 29 ref

014293   Roston G D (Physics Dep, Alexandria University, Alexandria, Egypt) : Effect of the interatomic potentials on the broadening and shifting of the intercombination spectral lines of Hg, Cd and Zn by inert gases. Indian J pure appl Phys 2004, 42(3), 167-71.

The Van der Waals and Lennard-Jones potential parameters for the ground and exited states of the second group elements (Hg, Cd and Zn) perturbed by inert gases (Xe, Kr, Ar, Ne and He) have been calculated using coulomb approximation. The basis of the Lindholm-Foley impact theory and the calculated potential parameters are used for calculating the collision broadening and shift coefficients β and δ for the intercombination lines 253.7, 326.1 and 307.6 nm of Hg, Cd and Zn atoms respectively, when they are colliding with inert gas atoms. The calculating coefficients of β and δ are compared with their corresponding experimental values, taken from literatures.

3 illus, 3 tables, 18 ref

014292   Rajendran A;Neelamegam P (PG and Research Department of Applied Physics, Nehru Memorial College, Puthanampatti, Tiruchirappalli-621 007) : Design and development of microcontroller based conductivity measurement system. Indian J pure appl Phys 2004, 42(3), 182-8.

A real time microcontroller based conductivity measurement setup has been developed to measure conductivity by investigating ionic solutions using a modified AC Wheatstone bridge network. This instrument system permits recording of conductivity and temperature and send data to personal computer to enable the computer processing of such data. A dedicated 8031 (8-bit) based microcontroller board was employed for the hardware. The details of its interface to measure conductivity, temperature and to control the temperature and evaluate results are explained.

7 illus, 17 ref

014291   Pata A (Sol-Gel division, Central Glass & Ceramic Research Institute, Jadavpur, Kolkata-700 032) : Up converted nanoparticles for photonic applications. Indian J Phys-Pt A 2004, 78(1), 43-5.

The effects of the erbium concentration, crystal hosts and co-dopant on the up converted emission of Er³⁺ in oxide nanocystals are reported. The effects of the Er³⁺ concentration and co-dopant (Yb>3+ in the ZrO2 matix on the up converted emission are reported. The presence of co-dopant (Yb³⁺) also increases the overall intensity of the up converted emission. A cw diode laser at 975 nm was used as a pump source for resonant sequential excittion of the ⁴l11/2 and ⁴F7/2 levels. Green and red up conversion emission at 550 nm and 670 nm were observed from these oxide nanocrystals with 975 nm excitation. The overall intensity decreases with an increasing concentration of erbium in different hosts. In up conversion emission intensity for the same concentration Er ions, BaTi3 host showed a highest up conversion emission intensity that that of ZrO2 and TiO2 host. The emission spectra and the pump intensity dependence of the luminescence intensities confirm that up converted emission in these materials is due to two-photon excited-state absorption (ESA) process.

3 illus, 7 ref

014290   Ningthoujam R S;Gajbhiye N S (Department of Chemistry, Indan Institute of Technology, Kanpur-208 016) : Magnetic and current density studies on nanostructured vanadium nitride material. Indian J Phys-Pt A 2004, 78(1), 89-91.

Nanostructured vanadium nitride material is prepared by chemical synthesis route. Atomic force microscopy study shows the particle size of 40 nm. Topography of the surface is studied. This shows the superconducting property at Tc <95>9.2K which can be confirmed from the electrical resisitivity studies. The magnetic data is fitted by using χ <61> χo^+C/T in temperature range 10-300 K indicating Curie-law at low tempeatures and Pauli-paramegnetism at high temperatures. Critical current density value is found to be 68 A/cm² which is the minimum limit of current density that can destroy the superconducting property.

5 illus, 6 ref

014289   Nikam P S;Hasan M;Pawar T B;Sawant A B (P G Dep of Physical Chemistry, M S G College, Malegaon Camp-423 105) : Ultrasonic velocity and allied parameters of symmetrical tetraalkyl ammonium bromides in aqueous ethanol at 298.15 K. Indian J pure appl Phys 2004, 42(3), 172-8.

Ultrasonic velocities in solutions of tetraalkyl ammonium bromide, R₄NBr (R = CH₃ through n-C₄H₉), NaBPh₃₄ and NaBr in ethanol-water mixtures were measured at 298.15 K by using a single-crystal interferometer at a frequency of 2 MHz. The ultrasonic velocity, density and concentration were used to calculate adiabatic compressibility, apparent molar compressibility, intermolecular free length, specific acoustic impedance, relative association and solvation number. Bachem and Gucker's laws have been found to be valid.

2 illus, 3 tables, 24 ref

014288   Narasimha Rao K (Instrumentation Dep, Indian Institute of Science, Bangalore-560 012) : Optical and electrical properties of indium-tin oxide films. Indian J pure appl Phys 2004, 42(3), 201-4.

Indium-tin oxide films find several applications because of their excellent properties such as high optical transparency, good electrical conductivity, high infrared reflectance etc. Achieving these properties depend on the choice of the deposition technique and the control of process parameters. It is all the more beneficial if these properties are to be realized at ambient temperature and without post deposition heating. In this investigation, indium-tin oxide films have been deposited by reactive electron beam evaporation of In+Sn alloy both in neutral and ionized oxygen environments. A low energy ion source has been used to ionize oxygen. Films deposited with neutral oxygen exhibited very low optical transmittance (5% at 550nm). Highly transparent (90%) and low resistivity (5x10^-4 ohm cm) films have been deposited on glass in ionized oxygen at ambient substrate temperature. As deposited films on ambient substrate with very low resistivity obtained by evaporation, are very significant.

2 illus, 1 table, 18 ref

014287   Mishra P R;Singh A K;Srivastava O N (Department of Physics, Banaras Hindu University, Varanasi-221 005) : Synthesis of nanostructured TiO₂ by sol-gel technique for PEC application and its advantages. Indian J Phys-Pt A 2004, 78(1), 81-4.

Deals with the syntehsis, characterization and fabrication of PEC solar cell employing nanostructured TiO2 photoelectrods materials. The nanostructured TiO2 have been formed on Ti-sheet (1 sq. inch and 0.1 mm thickness) by the hydrolysis of titanium tetra-isopropoxide Ti[OCH(CH3)2]4] followed by the deposition of thin film through spin on technique. it has been found that the average grain size of the as synthesized TiO2 about -8 nm. The PEC characteristics and hydrogen production rates utilizing nanostructured TiO2 and in the configuration Ti/ns--TiO2//1M-NaOH//Pt have been determined. The hydrogen production rates for the nanostructured TiO2 get enhanced to 14.25 lh^-1m^-2 as compared 6.12 lh^-1m^-2 from the convential TiO2 photoelectrode materials.

3 illus, 7 ref

014286   Meher H;Hosain S I (Fiber Optics and Opteolectronics Group Post Gradutate Department of Ph, G.M. College, Sambalpur - 768004) : Effect of refractive index dip on splice loss in graded-index single-mode fibers. J Optics 2003, 32(3), 107-18.

The effect of refractive index dip on splice loss in arbitrarily graded-index single-mode fiber has been studied utilising the four-term polynomial formula and the infinite sum representation for power transmission coefficient. In the former case, a highly accurate single parameter variational approximation,has been used whereas in the latter,infinite sum of the Laguerre-Gaussian functions for the representation of the LP₀₁ mode has been used. The results obtained by the infinite sum respresentation represent the exact results.

5 illus, 20 ref

014285   Manocha S M (Department of Materials Science, Sardar Patel University, Vallabh Vidyanagar-388 120) : Development of multielement nanostructured ceramics through solution route. Indian J Phys-Pt A 2004, 78(1), 111-14.

The silicon and transition metal alokoxides are very important as an area of sol-gel science and technology because of their simple processing and well-known hydrolysis/condensation reactions. Especially methyltrethoxysilane (MTES) is typical precursor. Hybrid gel prepared from silane after heat treatment and pyrolysis leads to Si-C-O nanuceramics hybrid gel. These are expected as good anti oxidation materials. Mixed carbides of Si, Zr and Ta have been developed in laboratory using sol-gel method. Metalakoxides of these metals have been cohydrolysed with addition of a carbonaceous source in appropriate ratios. These modified gels have been heated to 1000-1700°C. The transformations taking place during heat treatments have been studied by FTIR, NMR and XRD. these nanostructured ceramics have been characterized for thermal stability in oxygen environment and are found to posses superior oxidation resistant properties.

8 illus, 8 ref

014284   Majumder T P;Ikegami K (Department of Physics, krishnanagar Government College, Krishnanagar-741 101, Nadia) : Physical characterization of organic-inorganic hybrid charge transfer complexes. Indian J Phys-Pt A 2004, 78(1), 93-5.

It was confirmed experimentally that a certain chemical reaction occurs in alkyl TCNQ-Cul mixed Langmuir films prepared on pure-water surfaces. the degree of charge tansfer was estimated at -1. The UV-visible and IR absorption spectra of mixed LB films is discussed with variation of molar mixing ratios, although no such frequency shift of virbrational modes with different molar mixing ratios were observed. Does not find any significant structural differences among several molar mixing ratios of C15TCNQ-Cul mixed LB films, except the change in molecular orientation of TCNQ chromophore and alkyl chain part.

2 illus, 10 ref

014283   Maity R;Kundoo S;Ghosh P K;Chattopadhyay K K (Department of Physics, Jadavpur University, kolkata-700 032) : Synthesis and characterization of nanocrystalline zinc sulphide by wet chemical route. Indian J Phys-Pt A 2004, 78(1), 121-4.

Nanometer-sized ZnS crystallites were synthesized by a wet chemical synthesis process. Thin films of these nanocrystllites were also prepared on glass substates and annealed in vacuum at various temperatures. The nanocrystalline powders were charcterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies. The thin films were characterized by UV-visible optical absorption spectroscopy. XRD and TEM data confirmed the nano sizes of the crystallites. Also they showed the typical interplanar spacings (d value) corresponding to the cubic phase of ZnS. Band gap valaue increased in the nanomaterial than the bulk value. Sizes of the nanocrystallites were also determined from the band gap shift. Annealing of the thin flims modified the band structure and particle sizes were increased.

7 illus, 12 ref

014282   Kundu T k;Chakravorty D (Department of Physics and Technophysics, Vidyasagar University, Midnapore-721 102) : Conventional ceramic route for the production of nanocrystalline ferrites. Indian J Phys-Pt A 2004, 78(1), 53-5.

Niobium (Nb⁵⁺) ion doped maganese ferrites (MnFe2O4) and magenese-zinc ferrites (MnZn)Fe2O4 are developed by the conventional ceramic route. Nanostructured particles are found to evolve with increasing dopant concentration. Formation of nanoscale domains of ferrite is evident from the study of transmission electron micrographs. Typically the minimum size of the grain is Nb⁵⁺ doped MnFe2O4 lies in the range of 13.7 nm. Magnetic parameters like Curie temperature and Coercive field show a strong dependence on the size of the ferrite grains. It is concluded that the aliovalent ions break up the ferromagnetically active oxygen polyhedra and the sizes of the grains are reduced.

2 illus, 2 table, 12 ref

014281   Kranti A;Rashmi;Haldar S;Gupta R S (Semiconductor Devices Research Laboratory, University of Delhi, South Campus, Benito Juarez Road, New Delhi-110 021) : Modelling of threshold voltage adjustment in fully depleted double gate (DG) SOI MOSFETs in volume inversion to quantify requirements of gate materials. Indian J pure appl Phys 2004, 42(3), 211-20.

An analytical model is developed for volume inversion in DG SOI MOSFETs to study the impact of silicon film thickness, work function difference between gate and substrate, and gate voltage on electric potential, electron density and sheet density of mobile charges. The proposed model is extended to predict the threshold voltage of devices with different gate materials and quantifies the gate material requirements of symmetric self-aligned DG MOSFETs. A limiting criterion is developed on doping level and film thickness to ensure the occurrence of volume inversion in fully depleted DG SOI MOSFETs. Close proximity with simulated results confirms the validity of the present model.

5 illus, 1 table, 23 ref

014280   Karmakar B;Heide G;Frischat G (Professur fur Glas und Glastechnologie, Institut fur Nichtmtallische Werkstoffe, Technische Universiat Clausth, D-38678 Clausthal-Zellerfeld, Germany) : Comparative atomic force and scanning electron microscopic studies disclosing nanocrystallinity in cordierite glass-ceramics ; examples of surface modification. Indian J Phys-Pt A 2004, 78(1), 47-51.

The atomic force misroscopy (AFM), because of its unique features, can be used for a variety of applications and provides excellent research and development oppurtunities in the area of nanoscience and nanotechnology of glass and glass-ceramics. In this study, microscopic experiments have been carried out using both AFM and SEM on polished and etched as well as fracture cordierite glass-ceramic surfaces to unfold their comparative capabilities. Most importantly, it has been exhibited that the AFM is capable to ascertain single tiny crystallites originated at the begining of crystallization of galsses before scanning electron microscope (SEM) or X-ray diffraction (XRD) detects them. AFM provides extraordinary two-demensional (2D), three dimensional (3D), and quick surface plot (QSP) formats of images with unobscured (since no coating is necessary) views of nanostructures rather than obscured (since conducting coating is essential for insulators such as glass and glass-ceramics) and only 2D microstructural profiles of SEM. Development of interatomic forces (extended up to tens to hundreds of angstorms from the sample surface) between the atoms of the very sharp tip (probe) and those of surface (sample) during measurement results in unprecedented resolution (-0.1 nm) of images in AFM. While SEM produces images (resolution -10 nm) based on secondary electron emission from the sample surface. By comparing the results with those of SEM experiments, the AFM is established as a simple and powerful technique for the characterization of nanostructures of glas-ceramics particularly of early stages of crystallization.

8 illus, 11 ref

014279   Kant K;Chakarvarti S K (Department of Physics, K L Mehta Dayanand College for Women, N H 3, Faridabad-121 001) : Radiological impact of airborne radon and its progeny in dwellings. Indian J pure appl Phys 2004, 42(3), 157-61.

Measurement of indoor radon and its progeny levels was carried out in some typical dwellings made up of baked mud bricks, fly ash bricks, concrete blocks and mud housed using LR-115, Type II plastic track detectors in various districts of Haryana. The Potential Alpha Energy Concentration (PAEC) varied from 4.36 to 14.53 mWLl Equilibrium Equivalent Concentration (EEC) of radon varied from 40.33 to 134.40 Bq m^-3, annual exposure varied from 0.18 x 0.60 WLM; annual effective dose varied from 0.69 to 2.31 mSv and life-time fatality risk varied from 0.54 x 10^-4 to 1.8 x 10^-4 in the environment of dwellings in various districts of Haryana. The effect of various parameters on radon concentration such as seasonal variation and type of building materials was also studied. The radon concentration in industrially polluted cities like Faridabad, Panipat, Rewari, Yamun Nagar was found to be more. The measured radon and its progeny levels were the highest in winter season. In the measurements, it was found that radon concentration was the maximum in fly ash houses.

3 tables, 26 ref

014278   K Nandi;Chattopadhyay;Ghosh S;Das D;Jana D (NO, Gurudas College, Kolkata-700 054) : Oxidation mechanism of Si nanoparticles grown by plasma-CVD. Indian J Phys-Pt A 2004, 78(1), 57-60.

The oxidation behaviour nead kinetics of oxidation of amorphous silicon nanoparticles grown by plasma-enhanced CVD were investigated. The hydrogen content of the particles has a great influence on the oxidation rate. Oxidation experiments performed in a thermo-balance in an atmosphere of dry air with a steady heating ramp show that the onset of oxidation shifts to higher temperatures when hydrogen contents were reduced by annealing in inert atmosphere. Apparently, the higher oxidation rate of as-grown particles is due to the large density of dangling bond that are left behind just after the hydrogen is desorpted. The oxidation and dehydrogenation processes have been investigated by thermo-gravimetry (TG), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) analysis. The kinetics of oxidation of the completely dehydrogenated powders has been investigated under isothermal conditions. The kinetics was found to follow a parabolic law even at the relatively low temperature of oxidation indicating that the oxidation process is always controlled by oxygen diffusion. The structural changes and the growth of crystallites with oxidation temperature have also been studied.

5 illus, 15 ref

014277   Jana A;Mandal T K;Ram S;Kundu T K (Department of Physics, Salidha College, Bankura, West Bengal, ) : Synthesis of BaTiO₃ nanoparticles through a novel chemical route with polymer precursor. Indian J Phys-Pt A 2004, 78(1), 97-9.

Barium titanate (BaTiO3) nanoparticles have been synthesized through a chemical route using polyvinyl alcohol (PVA). The polymer is used to encapsulate the cations in divided groups that ulitmately control the growth of the ferroelectric particles. The particles size estimated from XRD data lies in the range 25 nm to 60 nm. The Curie temperature decreases with decreasing the grain size. It is important to notice that the material with a grain size of 30 nm still shows ferroelectricity. This is because the BaTiO3 nanoparticles are in a cluster and therefore remain in tetragonal structure though the size of individual is very small.

4 illus, 13 ref

014276   Gunasekaran S;Ponnambalam U;Muthu S;Anand G (PG & Research Phys Dep, Pachiyappa's College, Chennai-600 030) : Vibrational spectra and molecular structural investigation of quiniodochlor. Indian J pure appl Phys 2004, 42(3), 162-6.

A normal coordinate analysis on quiniodochlor has been carried out with a systematic set of symmetry coordinates following Wilson's F-G Matrix method. The potential constants evaluated for the molecule are found to be in good agreement with literature values thereby confirming the vibrational assignments. To chick whether the chosen set of vibrational frequencies contribute maximum to be potential energy associated with the normal coordinates of the molecule, the potential energy distribution has been evaluated.

2 illus, 1 table, 8 ref