000091   Siva Prasad R;Rajeshwara Rao U;Krishna D V (Mathematics Dep, Sri Krishnadevaraya University, Anantapur, A.P.) : Unsteady flow through a porous medium in a vertical channel under a transverse magnetic field. Acta Cienc Indica-Math 2003, 29(2), 305-16.

Unsteady magnetohydrodynamic flow of an electrically conducting viscous fluid in a vertical plate channel through a porous medium under transverse magnetic field has been discussed. The plates are maintained at different temperatures and the heat transfer sets in because of temperature gradient. The governing equations are derived using Brinkman's model and assuming that the magnetic Reynolds number is much less than unity the induced magnetic field is neglected in comparison to the applied magnetic field. The flow is maintained at an imposed oscillatory pressure gradient and keeping this in view the exact equations governing the flow are formulated with the oscillatory time dependence in the flow field. The velocity, the temperature, the shear stress and the Nusselt number have been evaluated analytically and their behaviour for variations in the governing parameters has been numerically discussed using computational methods.

9 illus, 5 tables, 19 ref

000086   Shukla P K;Tyati S K (Mathematics Dep, K.G.K. College, Moradabad, U.P.) : Note on Navier-Stokes equation for MHD flows. Acta Cienc Indica-Math 2003, 29(1), 35-6.

Navier-Stokes equation for MHD flow has been represented under a magnetic field with conservative Lorentz forces and have established that the equation for self-superposable flow represent the rate of change of vorticity due to molecular diffusion. It has also been shown that for a steady self-superposable MHD flow under a magnetic field with conservative Lorentz force the molecular diffusion of vorticity vanishes. Some solutions of the equation have been discussed and an idea of vorticity potential and equipotential surfaces for vorticity has been developed.

6 ref

000085   Shukla P K;Singh A P (Mathematics Dep, K.G.K. College, Moradabad, U.P.) : Hydro-dynamic flow of conducting fluid in force-free magnetic field. Acta Cienc Indica-Math 2003, 29(1), 25-6.

Some simple force-free magnetic fields are studied using the phenomenon of hydrodynamic self-superposability. It is shown that some important force-free fields like shear magnetic fields and the force-free fields with cylindrical symmetry can be studied with the help of the phenomenon of magneto-hydrodynamic self-superposability.

5 ref

000084   Shukla P K;Rajesh Ranjan (Mathematics Dep, K.G.K. College, Moradabad, U.P.) : On the vorticity of the MHD flow in a rectangular duct. Acta Cienc Indica-Math 2003, 29(1), 9-12.

Magnetohydrodynamic flow through rectangular duct with conducting walls is considered. An attempt has been made to study the vorticity of the flow and the effect of wall conductivity. The possibility of the irrotational motion in the duct has also been investigated.

7 ref

000070   Roy Chowdhury S K (Mathematics Dep, Kanchrapara College, Kanchrapara; North 24 (PGS), West Bengal) : Shear flow of an electrically conducting liquid past a cylinder with cross-section in the form of a cycloid. Acta Cienc Indica-Math 2003, 29(2), 401-7.

The two dimensional non-uniform shear flow of an electrically conducting inviscid, incompressible fluid past a cylinder having cross-section in the form of a cycloid in presence of a magnetic field aligned with the flow, has been studied. Introducing the stream function and magnetic field function, the governing equations have been solved in terms of curvilinear co-ordinates. The nature of the velocity and magnetic field components on the boundary of the cylinder have been shown graphically.

4 illus, 3 ref

000066   Rathy R K;Saini D P S (Mathematics Dep, Charan Singh University, Meerut, U.P.) : Hydromagnetic thermal instability of a second order fluid flow between two parallel porous planes. Acta Cienc Indica-Math 2003, 29(2), 337-43.

The hydromagnetic thermal instability of unidirectional flow of density stratified second order fluid has been discussed in presence of a constant, transverse magnetic field by taking injection velocity as one plane to be equal to suction velocity at the other plane in order that the basic velocity transverse to the plane is constant. It has been shown that second order fluid parameter S has destablizing effect. Also growth rate of stable or unstable modes do not depend on suction injection velocity explicitly. It depends on suction injection velocity only through basic velocity distribution.

10 ref

000062   Ramakrishna S;Sreedhara Rao G;Venkataramana S (Mathematics Dep, S.V. University, Triupati-517 502) : Heat transfer in free surface flow of a Bingham fluid over a permeable bed. Acta Cienc Indica-Math 2003, 29(2), 369-75.

Heat transfer in free surface flow of a Bingham fluid bounded below by a permeable bed is studied. The width of the channel is h, z-axis is taken along the nominal surface of the permeable bed and x-axis is perpendicular to it. The flow in the non-porous region is divided into three zones. The region between x = 0 and x = x₁ is called zone I and that between x = x₁ and x = x₂ is called plug flow region. The region between x = x₂ and x = h is called zone II. The flow over the permeable bed is described by Bingham model. The velocity distribution, the temperature distribution, the temperature distribution, the shear stress, the fractional increase in mass flow rate, the rate of heat transfer are obtained and the results are numerically discussed.

3 illus, 5 ref

000032   Hossain M;Mukherjee S;Mukherjee S (Mathematics Dep, N.M.S. High Madrasah (H.S.), Malda-732 206) : MHD free convective flow and mass transfer through an inclined open rectangular channel. Acta Cienc Indica-Math 2003, 29(2), 329-35.

A theoretical analysis of the steady MHD free convective flow and mass transfer of an electrically conducting viscous incompressible fluid through an inclined open rectangular channel with varying permeable bed is presented. An exact solution for velocity, temperature and concentration of fluid is obtained using finite Fourier Sine Transform. The effect of Prandtl number, Eckert number and magnetic parameter is studied.

3 illus, 6 ref

000029   Govindarajulu T;Cornelius J S (Mathematics Dep, Madras Institute of Technology, Chennai-600 044) : Convective flows in porous vertical triangular channel with a heat source. Acta Cienc Indica-Math 2003, 29(2), 419-23.

The problem of free and forced convections in a porous vertical equitriangular channel, in the presence of a variable heat source, is studied. The fluid generates heat which is a linear function of the local temperature. Exact solutions have been obtained for the velocity and temperature fields for the flow in equitriangular channels in the presence of variable heat source. The expression for mean mixed temperature is obtained.

1 illus, 4 ref

000006   Balbir Chand;Ashok Kumar;Kaushik V P (Math Dep, Govt National P.G. College, Sirsa (Haryana)) : Magnetic field effects on the free convection and mass transfer flow through porous medium with time dependent suction and constant heat flux. Bull Calcutta Mathl Soc 2003, 95(3), 259-72.

9 illus, 1 table, 16 ref

000002   Aziz A;Das U N;Ahmed S (Dep of Math, Karimganj College, Karimganj (Assam)) : Heat transfer in three dimensional flow along an infinite horizontal porous plate through a porous medium in presence of transverse magnetic field. Bull Calcutta Mathl Soc 2003, 95(2), 127-36.

Three dimensional flow of a viscous incompressible fluid through a highly porous medium and past an infinite flat plate with sinusoidal suction velocity and transverse magnetic field has been investigated. The temperature field has also been considered. Analytical solutions for the velocity and temperature fields in the boundary layer flow have been obtained neglecting the induced magnetic field. The effect of the flow and heat transfer parameters on the skin friction and the rate of heat transfer at the plate are discussed in detail.

2 illus, 1 table, 10 ref

004260   Vogel W (NO, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany) : Characterization of Nanoparticles using X-Ray diffraction. Phys Educ 2002, 19(1), 47-58.

X-ray diffraction (XRD), normally known to be a volume effect, becomes progressively surface sensitive with decreasing size of the scattering objects. XRD is therefore increasingly used in fields like supported catalyst or semiconducting materials. The major advantage is its ability to perform measurements under in-situ conditions. XRD averages over a large volume and therefore complements to the local nature of electron microscopy. Recent developments in numerical and instrumental techniques are presented. Some few examples of applications with emphasis on heterogeneous catalysts are demonstrated, as bimetallic Pd-Pt colloids, the Au₅₅ [P(C₆H₅)₃]₁₂Cl₆ molecular cluster, and the standard platinum catalyst Euro Pt-1.

8 illus, 20 ref

004259   Verma S S (Dep of Phys, , S.L.I.E.T., Longowal, Dist. Sangrur (Punjab) 148 106) : Low temperature techniques. Phys Educ 2002, 18(3-4), 251-4.

The study of matter and physical principles near absolute zero has always fascinated researchers from various disciplines of science and engineering. Lower temperature have led to unexpected discoveries such as superconductivity, superfludity, Bose-einstein condensation and nano-technology, etc. Some of the low temperature techniques employed to reach to such low temperature are discussed.

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004258   Thakur N;Sharma D R (Phys Dep, , Shimla-171 005) : Dielectric relaxation of Acetonitrile in Benzene solution from Microwave absorption studies. Indian J pure appl Phys 2003, 41(10), 806-9.

The dielectric constant ε" for dilute solutions of acetonitrile (CH₃CN) in benzene have been measured at 10.04 GHz at different temperatures (25, 30, 35 and 40°C) by using standard microwave techniques. Following the single frequency concentration variational method suggested by Gopala Krishnana, the dielectric relaxation time (τ) and dipole moment (μ) at various temperatures have been calculated. It is found that, dielectric relaxation process can be treated as the rate process, just like the viscous flow. Based upon above studies, monomer structure foer CH₃CN in benzene solution has been inferred. The presence of solute-solvent association in benzene solution has been proposed. Energy parameters for the dielectric relaxation process of CH₃CN in benzene at different temperatures have been calculated and compared with the corresponding energy parameters for viscous flow.

1 illus, 2 tables, 12 ref

004257   Srivastava S K;Kolhe K G;Anjane J B (Sch of Phys, D A Univ, Indore) : Elastic constants and structure factor of alkali halides. Indian J pure appl Phys 2003, 41(10), 771-4.

A new band structural approach has been developed for the pair potentials of molten alkali halides salts. Short range part, φ^s_αβ(r) of pair potential has been employed for computer simulation work of force constants and elastic constants C₁₁, C₁₂ and C₄₄ of NaCl, NaI, KCl, RbCl molten salts. The Fourier transformed quantity of momentum q-space φ^s_αβ(q) in the light of liquid phonon spectrum gives a new fruitful concept for the evaluation of structure factors, S_αβ(q) of above materials.

2 illus, 1 table, 9 ref

004256   Shyam Singh (Phys Dep, Univ of Namibia, Private Bag 13301, Windhoek, Namibia) : Measurement of refractive index of liquids using He-Ne laser and thin transparent glass cell. Res J Chem Envir 2003, 7(1), 62-3.

A very simple and efficient method has been proposed for the measurement of the refractive index of a liquid using a He-Ne laser and a thin transparent glass cell. This method does not require the knowledge of the angle of incidence or angle of refraction or angle of deviation of the laser beam. Experimental values for the index of refraction of water and some liquids have been reported.

1 illus, 2 tables, 5 ref

004255   Sharma R et al (Thin Film and Semiconductor GT Patil Coll, , Nandurbar-425 412) : Effect of preparation procedures on long-term performance of SnO₂ thin film sensing layers deposited with different methodologies. Indian J pure appl Phys 2003, 41(10), 749-66.

There is an increasig demand for SnO₂ semiconducting gas sensors for several monitoring applications that have sensitivity, selectivity and reliability on a long-term scale. The long-term performance of SnO₂ thin film sensing layers, which strongly depend on the preparation procedures and different thin film deposition techniques have been reviewed. The stability and reliability are very important for tin dioxide based gas sensor devices, when these are to be integrated with standard CMOS circuitry. The stability in the output of the thin film sensing layer is very essential to implement reliable integrated sensor device, because a small drift in the baseline leads to a large change in the biasing current in the subsequent signal processing circuit. The long-term stable behaviour of the SnO₂ thin film gas sensor has been found in the literature and it depends on the thin film deposition conditions, annealing temperature, time, ambient, and noble metal/metal oxide dopant. It can be seen from the literature that, sensitivity and stability of SnO₂ this film were strongly affected with variation in the crystallite (grain) size and growth procedures. The thin films were deposited by chemical methods such as, screen-printing, sol-gel, spray pyrolysis, etc. and physical methods such as, RGTO, sputtering, PLA, etc. with the grain size varying from 5 to 50 nm with annealing temperatures varying in the range 500-800°C and with noble metal/metal.

^iia28 illus, 1 table, 72 ref

004254   Shah N A;Malik M A (Postgrad of Electronics & Instrumentation Techno Dep, Univ of Kashmir, Srinagar-190 006) : FTFN based universal voltage-mode filter. Indian J pure appl Phys 2003, 41(10), 814-6.

A novel configuration for realizing voltage mode (VM) universal biquad filter based on and employing a single for terminal floating nullor (FTFN), a single voltage follower and four passive components has been presented. The circuit has three inputs and one output and supports lowpass (LP), bandpass (BP), highpass (HP), notch and allpass (AP) filtering signals from the same configuration, besides being free from the component matching conditions. The bandwidth ω₀/Q and cut-off frequency ω₀ are orthogonally tunable. The circuit has low sensitivity figures and has the additional advantage of being canonical. Simulated resutls have also been presented.

5 illus, 7 ref

004253   Quamara J K;Sridharbabu Y (Appl Phys Dep, Regional Engineering Coll, Kurukshetra-136 119) : Thermally stimulated Depolarization current studies in pristine an d100 MeV Ni-ion irradiated PET/0.3PHB polymer liquid crystal. Indian J pure appl Phys 2003, 41(10), 790-800.

Thermally stimulated depolarization current (TSDC) characteristics of Pet/0.3PHB polymer liquid crysta, a copolymer of polyethylene terephthalate and p-hydroxy benzoic acid, have been studied as a function of the polarizing field (38.5-192.3 kV/cm), polarizing temperature (80-220°C), heating rate (2-6°C/min), storage time (0-960 h) and electrode material (Au, Al, Cr). The TSDC spectra in general comprise of three maxima namely β, β' and α with their respective location around 35, 122 and 155°C. The β-peak has been attributed to the dipolar orientation relaxation of PET rich phase. The α-peak has been ascribed to the space charge relaxation. A major contribution towads α-relaxation comes from PHB-rice phase and the cold crystallization of PET-rich phase. The pesence of a rigid amorphous phase (γ-relaxation) appears to affect the true nature of αpeak. A high temperature maxima around 190°C in TSDC spectra of high temperature poled samples is due to melting ((°-relaxation). The β-peak is ascribed to the extremely fast reacting dipoles of PHB and PET phase. The TSDC spectra of PET/0.3PHB samples irradiated with 100 MeV Ni-ion beam (Fluence: 3.39x10¹⁰, 8.93x10¹⁰, 3.13x10¹¹ ions/cm²) show the presence of new energy traps (deep/shallow)....

9 illus, 1 table, 30 ref

004252   Purohit G (NO, Cen for Energy Studies, Indian Ins of Technol, Hauz Khas, Delhi-110 016) : An introduction to nonlinear optics. Phys Educ 2002, 18(3-4), 209-19.

Nonlinear optics is a new frontier of science and technology. It was opened by the advent of lasers with high peak powers. Nonlinear optics holds the key for the future technology of photonics which would utilize optical frequency conversion, optical signal processing and image processing using ultrashort laser pulses. An overview of the nonlinear optics is presented.

^iia9 illus, 1 table, 20 ref

004251   Purandare R;Patil S (Dep of Phys, Univ of Pune, Pune-411 007) : Carbon nanotubes. Phys Educ 2002, 19(1), 81-4.

A brief account carbon nanotubes is given. Various synthesis methods, viz. arc deposition, laser deposition, chemical vapour deposition are discussed and different characterization techniques such as Scanning Tunneling Microscopy/ Scanning Tunneling spectroscopy, Transmission Electron Microscopy, etc are introduced. The role of carbon nanotubes in modern technology is stated in brief.

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004250   Patel T H;Vaida R;Patel S G (Phys Dep, Sardar Patel Univ, Vallabh Vidyanagar, Gujarat-388 120) : High pressure electrical resistance measurements on SnS_xSe_1-x single crystals. Indian J pure appl Phys 2003, 41(10), 785-9.

The ternary mixed single crystals of SnS_xSe_j-x (where x = 0, 0.25, 0.50, 0.75 and 1) were grown by direct vapour transport techinqe. The grown crystals were characterized by an X-ray diffraction analysis. Room temperature resistivity and Hall effect measurements were also carried out. From the optical absorption spectra, the values of band gap at atmospheric pressure were determined. The high pressure electrical resistance measurements were carried out, at room temperature, up to 8 Gpa, using Bridgman opposed anvil set method. The effect of pressure on the single crystals of the series SnS_xSe_1-x is reported systematically, in the context of intra-layer and inter-layer bonding in these crystals.

4 illus, 1 table, 26 ref

004249   Mahato D K;Chaudhary R K;Das N N;Srivastava S C (Mater Sci Centre, Natn Inst of Technol, Jamshedpur-831 014) : Thermal behaviour of spray dried PZT and PLNZT powders. Indian J pure appl Phys 2003, 41(10), 767-70.

Solid state reaction characteristics of powders prepared by spray drying the mixed nitrate solutions of Pb, Zr, Ti as well as Pb, Zr, Ti, La and Na have been studied using DTA-TGA and ZRD techniques. A relatively lower calcination temperature was found sufficient for formation of PZT/PLNZT indicating better homogeneity in the spray dried powders.

4 illus, 3 tables, 21 ref

004248   Mahaddalkar Y R;Bhawsar B D (Dep of Phys, Univ of Pune, Pune-411 007) : Synthesis of nanoparticles using microemulsions. Phys Educ 2002, 19(1), 85-9.

There is a growing interest in synthesizing nanoparticles using various methods for synthesis, such as physical and chemical methods. Synthesis of nanoparticles using microemulsion is one of the methods. By using microemulsion, it is possible not only to entrap the nanoparticles of desired size in nano-cavity produced by microemulsion, but also to obtain bio-compatible, bio-degradable materials often useful in drug-delivery. Formation of micelles, reverse micelles, microemulsion, properties and application of microemulsion are discussed. Synthesis of nanoparticles in microemulsion medium is also described.

3 illus, 6 ref

004247   Kowshik M;Paknikar K M (Div of Microbial Sci, Agharkar Res Inst, G.G.Agarkar Road, Pune-411 004) : Biological strategies for the production of metal-based nanocrystallites. Phys Educ 2002, 19(1), 31-40.

The use of nanosized materials is becoming more widespread due to their unique size related properties. Various physical and chemical methods are currently in use for the production of such nanomaterials. Use of biological strategies for the production of metal-based nanocrystallites have been discussed.

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004246   Kistaiah P;Sagar P K D;Venkat Reddy P; Veeraiah N (Phys Dep, Osmania Univ, Hyderabad-500 007) : Optical absorption and photoluminescence properties of Eu<. Indian J pure appl Phys 2003, 41(10), 780-4.

Several physical, optical absorption ad photoluminescence properties of Eu³⁺ doped KF-B₂O₃ glasses have been studied. From the measured intensities of various absorption bands of these glasses the Judd-Ofelt parameters Ω₂, Ω₄ and Ω₆ have been computed. The Judd-Ofelt theory has been applied to characterize the photoluminescence spectra of these glasses. From this theory various radiative properties like, transition probabiolity (A), branching ratio (Ω₁) and emission cross-section (σ^E_p) for various emission levels of these glasses have been determined and reported.

3 illus, 3 tables, 29 ref

004245   Kirit K N;Raval K G;Arun Pratap (Condensed Matter Phys Lab, Appl Phys Dep, Fac of Technol & Engng, M S Univ of Baroda, Vadodara-390 001) : Study of concentration fluectuations in liquid Li-Na alloy. Indian J pure appl Phys 2003, 41(10), 810-3.

The concentration fluctuations in the long-wavelength limit, S_cc(0), in liquid Li-Na alloy have been studied using the Bhatia-March formula, re-derived for binary liquid alloys by Hoshino and Young from the first principle calculations. The effective inter-atomic pair potentials in the binary liquid alloy are obtained in the pseudopotential formulism. Since Li possesses simple 1s electronic structure, the choice of the pseudopotential is critical for it. The effect of the choice of the input parameter, namely core radius, in the Ashcroft pseudopotential and different local field correction to the dielectric function, on the effective pair potential in Li has been studied. It has been found that, the Ashcroft potential with a suitable choice of the core radius still works. The concentration dependence of S_cc(0) shows asymmetrical behaviour in qualitative agreement with molecular dynamics results of Moi et al., J Phys Soc Japan, 61 (1992) 1218. The asymmetrical behaviour indicates the phase separation tendency in the Li-Na alloy.

3 illus, 17 ref

004244   Kankate L (Dep of Phys, Univ of Pune, Pune-411 007) : Small angle X-ray scattering studies of nanoparticles. Phys Educ 2002, 19(1), 71-2.

^ssc1 illus, 2 ref

004243   Hebalkar N;Deshpande A (NO, , R&DE (Engrs), Dighi, Pune) : Nanoporous materials. Phys Educ 2002, 19(1), 77-9.

^iia2 illus, 7 ref

004242   Gupta K K;Bansal A K;Singh P J;Sharma K S (Phys Dep, M S J Coll, Bharatpur-321 001) : Studies on dielectric properties of cyclohexylamine in non-polar solvents-kirkwood correlation factor, molar polarization and excess free energy. Indian J pure appl Phys 2003, 41(10), 801-5.

The study of the dielectric properties of binary mixture of cyclohexylamine (CHA) in non-polar solvents such as benzene, n-heptane and 1,4-dioxane has been investigated. The low frequency molecular dynamics of CHA molecule have been studied by eveluating the Kirkwood correlation factor (g), molar polarization (p₂), excess correlation factor (δg) and exess free energy (ΔG_u). The observed values of g significantly deviated from unity, which confirm the inter-molecular association in CHA molecule in dilute solutions. The presence of α- and β-multimers in the above system was identified. CHA establishes H-bonding with oxygen of 1,4-dioxane resulting in reinforcement of inter-molecular association and causes higher values of g as compared to benzene and n-heptane. The high frequency molecular dynamics were examined using 8.93 GHz, which reveals that a single relaxation process exists in CHA. These parameters have been used to throw light on the dynamic characteristics of molecular association in these binary mixtures of polar-non-polar liquids.

1 illus, 2 tables, 18 ref

004241   Gupta D;Ghosh B (Dep of Physics, University of Burdwan, Burdwan-713 104) : Path-Integral Quantization in Single-Particle Mechanics and Field theory. Phys Educ 2002, 18(3-4), 195-201.

Path-integral quantization is an alternative method of quantization, which appears to have wider arena of applicability than that of the more familiar canonical method of quantization, especially in modern field theories. A brief and introductry overview of the path-integral quantization method both in single-particle mechanics and field theory has been presented. Connection of this procedure with the conventional ones has been elucated.

^iia7 ref

004240   Gangal S A;Kulkarni S K (Dep of Electronic Sci, Univ of Pune, Pune-411 007) : Towards Nano Lithography. Phys Educ 2002, 19(1), 5-18.

Currently there are two approaches, viz. lithography also known as top down approach and self assemply or bottom up approach to obtain materials of nanosize. Lithography is a process of transferring the geometric shapes on a mask to the surface of the substrate. This process plays a key role in Integrated Circuit Manufacturing, especially in deciding the minimum features size of the devices. Starting with the concept of lithography the optical and x-ray lithography technique used for mass production and e-beam lithography used mainly for mask making have been described. This is followed by emerging trends in nanolithography based on the use of scanning probe. A promising approach of "soft Lithography", an inexpensive method to print nano-devices for nano-circuits is then discussed.

^iia8 illus, 9 ref

004239   Ethiraj A S (Dep of Phys, Univ of Pune, Pune-411 007) : Synthesis of nanoparticles. Phys Educ 2002, 19(1), 73-5.

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004238   Deshmukh S V (NO, Centre for Advanced Technology, CAT P.O., Indore-452 013 (M.P)) : Laser interferometric and Faraday rotation techniques for plasma diagnostics. Phys Educ 2002, 18(3-4), 255-61.

Lasers are used for plasma diagnosis based on the principles of electromagnetic (e.m.) wave propagation through plasma. Plasma introduces phase shift in propagating e.m. wave due to change in refractive index. When a linearly plane polarized e.m. wave is passed through a magnetized plasma, parallel to the magnetic field, Faraday rotation is observed. These two effects are used for measuring plasma electron density. Lasers now available in FIR and visible regions are the most suitable source of e.m. wave fulfilling special requirements for these measurements. These nonintrusive techniques are useful for measuring electron density n_e <62> 10¹² cm^-3. Basic principles of propagation of laser through unmagnetized and magnetized plasma relevent to these diagnostic techniques are discussed. Conditions for selecting a low power laser of suitable wavelength for phase shift and Faraday rotation measurements are discussed. Expression for electron density measurements using phase shift and Faraday rotation are derived. Other conditions related to these diagnostic are also discussed.

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004237   Deshmukh M M;Ralph D C (NO, Lab of Atomic and Solid State Phys, Cornell Univ, Ithaca, NY 14853, USA) : Metallic quantum dots. Phys Educ 2002, 19(1), 41-6.

Quantum dots can be viewed as "artificial atoms" since they consist of a fixed number of electrons confined in a small area. They allow to probe the basic physics of many electron systems in regimes not accessible in real atoms. Experiments where one can probe magnetism at nanometer scale using a single magnetic nanoparticle as the quantum dot have been described.

5 illus, 11 ref

004236   Das S;Subbarao D;Tewari D P (NO, George Mason Univ and Center for Ocean Land Atmospheric Studies, Calverton, Maryland-29795, USA) : Nonlinear Faraday rotation of electromagnetic waves in magnetoplasma. Phys Educ 2002, 18(3-4), 183-90.

Nonlinear modification in the propagation characteristics and Faraday rotation of electromagnetic wave in the quasi-longitudinal regime, i.e. when the angle that the propagation vector make with the constant magneto-static field is very small have been considered. The Faraday rotation of the satellite waves generated because of the ponderomotive nonlinearity in the medium has also been derived. Aspects of a photonic crystal naturally formed in a magnetoplasma because of degenerate four-wave mixing have been brought out.

1 illus, 32 ref

004235   Bhoraskar S (Dep of Phys, Centre for Advanced Studies in Material Science, Univ of Pune, Pune-411 007) : Multifacets of porous silicon. Phys Educ 2002, 19(1), 19-30.

Nanocrystalline arrays of silicon form an important class of nanostructured materials, which are most conveniently realized in porous silicon. Electrochemically anodized silicon in a hydrofluric acid based electrolyte is shown to exhibit variety of applications in today's technology world. Besides the quantum confinement effects, describes other reasons responsible for the visible light emission from porous silicon. Examples of electroluminescence from hetero-junctions with other nanocrystalline materials are also cited. Various applications including those in biological fields are discussed.

^iia 10 illus, 15 ref

004234   Ashtaputre S;Kharrazi S (Dep of Phys, Univ of Pune, 411 007) : X-ray photoelectron spectroscopy of nanostructured materials. Phys Educ 2002, 19(1), 69-70.

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004233   Amirthaganesan G;Kandhaswamy M A;Srinivasan V (Chem Dep, Sri Ramakrishna Mission Vidyalaya Coll of Arts and Sci, Coimbatore-641 020) : Infrared and thermal studies in Methylammonium trichloromercurate (II) single crystals. Indian J pure appl Phys 2003, 41(10), 775-9.

Methylammonium trichloromercurate (II) (CH₃NH₃HgCl₃) single crystals have been grown by slow evaporation method at room temperature. The crystals obtained are colourless, bright, transparent and square-shaped platelets with an average size of 5x1.5x0.3 cm. The grown crystals have been characterized through elemental anaysis, powder XRD, thermogravimetry (TG), differential scanning calorimetry (DSC), FTIR and NMR spectroscopic techniques. The elemental analysis confirms the molecular formula of the title compound. The crystallinity of the synthesized compound is evident from well-defined and sharp Bragg peaks obtained in the powder XRD pattern. The decomposition pattern of the compound is formulated using the TG. Thermal anomalies observed in the DSC curves at 0.6 and -15.9°C duing the heating and cooling cycles are indicative of first-order structural phase transition in the crystal. The FTIR and far IR spectra show the characteristic absorption bands due to CH₃NH⁺₃ and HgCl^-₃ ions. The NMR spectrum inidcates the presence of only one kind of chemically and magnetically equivalent protons of the methyl group present in the compound.

8 illus, 1 table, 8 ref