010506   Ahmad Z (Physics Dep, Faculty of Science University of Maiduguri, P M B 1069, Maiduguri, Borno state, Nigeria) : On hadron production in the backward hemisphere in relativistic si-nucleus collision. Acta Cienc Indica-Phys 2002, 28(2), 95-104.

Experimental data involving interactions caused by 4.5 and 14.5 A GeV/c [28] Si-nuclei with emulsion are analysed to investigate various features of events produced with and without the emission of hadrons in the backward hemisphere. The findings reveal that the backward production of hadrons depend on the wounded part of the incident nucleus while the number of relativistic charged particles produced in the forward hemisphere depends on the probability of interaction of the projectile nucleons or the impact parameter. Dependence of (n_h on n^b_s gives a new criterion for selecting events due to complete destruction of AgBr nuclei. The finding based on the angular characteristics of relativistic charged particles indicate that the events having no hadrons in the backward hemisphere are produced either due to the interaction with CNO group of nuclei or arise because of the peripheral collisions with AgBr nuclei.

5 illus, 3 tables, 20 ref

023902   Wang W;Li W;Jian Y;Zhang R (Faculty of Materials Science and Chemical Engineering, Ningbo Univ, Ningbo-315 211, People's Republic of China, Email: wqwang@126.com) : Surface enhanced Raman scattering of rhodamine B adsorbed on polypyrrole-silver composites. J Polym Mater 2010, 27(4), 351-7.

Novel polypyrrole(PPy) microstructures were fabricated via the electrochemical oxidation of pyrrole in poly( 4-styrene sulfonic acid) aqueous solution. By the modified silver-mirror reaction, silver nanoparticles were deposited on surface of the PPy microstructures to form PPy-silver composites. The application of the as-prepared PPy-silver composites in surface-enhanced Raman scattering(SERS) was studied using Rhodamine B(Rh b) as probe molecules. The results showed that the PPy-silver composites exhibited excellence SERS ability and could be used as SERS-active substrates for detection of trace molecules.

4 illus, 1 table, 16 ref

023901   Vengurlekar A S (Condensed Matter Physics Dep, Tata Institute of Fundamental Research, Mumbai-400 005, Email: asv@tifr.res.in) : Extraordinary optical transmission through metal films with subwavelength holes and slits. Curr Sci 2010, 98(8), 1020-32.

Continuous films of metals like gold and silver with a thickness of a few tens of nanometres have poor transmission for visible and infrared light. However, the same films become largely transparent when the transmission is mediated by coupled surface plasmon polaritons on the two surfaces of the film. Likewise, it is expected that optical transmission through a hole in an opaque metal film would be negligible if the size of the hole is much smaller than the wavelength of the incident radiation. Contrary to this, it was found a few years ago that opaque metal films perforated with a periodic array of subwavelength holes exhibit large transmission at certain wavelengths. Such extraordinary optical properties of the metal films have attracted much attention in recent years. They have led to several proposals and demonstrations of nanophotonic applications in a wide range of areas such as microscopy, spectroscopy, optoelectronics, optical data storage, biochemical sensing and so on. Also, extensive effort has been made to elucidate the mechanisms of efficient light energy transfer across metal films with arrays of subwavelength apertures like holes and slits. Despite this effort, not all aspects of the underlying physics of the phenomena are fully understood yet. Here, we provide a short review of the various concepts put forth to explicate the large transmission of light across continuous metal films and films with subwavelength apertures.

10 illus, 83 ref

023900   Shukla G;Pushpa Devi;Rai D V (Microbiology Dep, Panjab Univ, Chandigarh-160 014, Email: geeta_shukla@pu.ac.in) : Effect of low magenetic field and voltage on the growth of Lactobacillus casei-a preliminary study. Panjab Univ Res J Sci 2008, 58(1-4), 73-8.

The study was designed with an aim to observe the effect of magnetic field/voltage on the growth pattern of Lactobacillus casei- a probiotic. Phenotypically, L. casei was found to be a gram positive, non motile, forming non pigmented pin head size colonies with smooth, glistening and convex surface. Biochemically, it was bile tolerant, catalase negative and capable of fermenting various sugars. It was further observed that the lag period of L. casei was prolonged (6 hours) under the influence of magnetic field as compared to control, thereafter, the growth increased exponentially, resulting into the alteration of pH of the medium. However, the growth pattern remained unaltered under the influence of low voltage and was identical to control group. Taken together, it seems that magnetic field prolongs the lag phase of L. casei and warrants further study.

5 illus, 20 ref

023899   Reena Devi;Ranjan Kumar (Physics Dep, Panjab Univ, Chandigarh-160 014, Email: ranjan@pu.ac.in) : Stability of Na and H atoms inside C₆₀ molecule-DFT calculations. Panjab Univ Res J Sci 2008, 58(1-4), 217-22.

Reports ab-initio molecular dynamics simulations of Na and H atoms inside C₆₀ using SIESTA. Authors found that the C-C bond lengths are in agreement with 1.40 and 1.45 Angstrum values reported earlier. Authors studied the stability, geometries and charge transfer from the system of Na-atoms and H-atoms to the C₆₀ molecule authors find that in case of Na_n@C₆₀ one can dope a maximum of four atoms inside a C₆₀ molecule. In case of H doping we have been able to dope 10 atoms inside C₆₀, but it may accommodate more without adsorbing to the inner surface of C₆₀.

4 illus, 2 tables, 14 ref

023898   Ravangave L S;Hiswankar S U (Physics Dep, Shri Sant Gadge Maharaj College, Loha, Nanded (M.S.)) : Effect of doping concentration of EU<. Bionano Front 2011, 4(2), 188-90.

The europium-doped LaF₃ nanoparticles were prepared by simple chemical co- precipitation method in ethanol solution and characterized with X-ray diffraction (XRD), Transmission electron microscopy (TEM), and photolumincscence spectroscpy. The results of XRD date signify that the LaF₃: Eu³⁺ nanoparticles were well crystallized with a hexagonal structure. The particle size calculated from XRD data was decreased with concentration of doping Eu³⁺ ion and average size is in the range of 21 to 28 nm. The TEM image illustrate the clusters of LaF₃: Eu^3+D natiopartieles with an average size rendered around 27 nm. The luminescence spectrum of LaF₃: Eu³⁺ nanoparticles exhibited the characteristic line emissions arising from the ⁵D₀ → (J=1, 2, 3, 4) transitions of the Eu³⁺ ions, with the dominating emission centered at 590 nm. The intensity of emission at 590 and 620 nm lines was increased with the doping concentration of Eu³⁺ ions.

3 illus, 6 ref

023897   Ranjan Kumar;Harkiran Kaur;Keya Dharamvir (Physics Dep, Panjab Univ, Chandigarh-160 014, Email: ranjan@pu.ac.in) : Charge transfer in endohedral na doped C₂₄₀ molecule. Panjab Univ Res J Sci 2008, 58(1-4), 207-11.

C₂₄₀ is a hollow molecule of carbon atoms. It is a large nearly spherical molecule having mean radius of about 7.11 Angstrum. It may accommodate guest atoms inside it. Therefore a number of Na atoms may be doped inside it. We have used the model potential calculations to investigate the stability and charge transfer when Na atoms are doped inside it. In our calculations, the number of the Na atoms doped inside C₂₄₀ varies from 4 to 9. The binding between Na atoms has been modeled using Gupta potential. The interaction between Na atoms and C₂₄₀ is modeled using 6-exp potential. We find that the charge transfer depends upon the number of Na atoms. For smaller clusters, charge transfer is energetically favorable compared with relatively large clusters. Therefore ionic character decreases with the size of cluster. The binding energy of the cluster also increases as the number of Na atoms increase.

2 illus, 1 table, 14 ref

023896   Rana J M S (Physics Dep, HNB Garhwal Univ, Tehri-Garhwal, Email: ranajms@gmail.com) : Vacuum structure of restricted quantum chromodynamics (RQCD). Panjab Univ Res J Sci 2008, 58(1-4), 267-75.

The isocolor charge-dyon interactions have been studied, in Restricted Quantum Chromodynamics (RCD), in terms of current-current correlation in magnetic gauge using the dielectric and permeability parameters of the associated vacuum, in the state of dyonic superconductivity, it has been shown that the dual propagators behave as 1/k4 (for small k2), which in analogy with superconductivity (dual superconductivity) leads to the confinement of colored fluxes associated with dyonic quarks vide generalized Meissner effect. Based on semi-quantitative analysis of vortex solutions of RCD and by calculating the masses for the massive collective modes of the condensed vacuum, the expressions for the London penetration depth, coherence length and the associated flux energy functions for the type I and type II superconducting media have been obtained. It has further been demonstrated that in the type I medium, vortices tend to coalesce and hence are attractive, while the energy function supports repulsive forces between vortices in the type II superconducting medium.

17 ref

023895   Rana J M S (Physics Dep, HNB Garhwal Univ, Tehri-Garhwal, Email: ranajms@gmail.com) : Implications of supersymmetric restricted quantum chromodynamics (SRCD) on dyonic solutions. Panjab Univ Res J Sci 2008, 58(1-4), 249-65.

The Restricted Quantum Chromodynamics (RCD) formulated in terms of connections on global spaces has been supersymmetrized, in a general manner, taking only the topological part into considerations. Dyonic supermultiplets have been obtained for the N=1 supersymmetry quantum mechanically as well as in the supersymmetric version of Georgi-Glashow model for vanishing linear momentum and in the Clifford vacuum. Incorporating the Dyonic color charge and color spin induced as a result of fermion fractionization in Georgi-Glashow model(in presence of an isovector fermion field)into the Supersymmetric Restricted Chromodynamics in N=1 SUSY limit,the Lagrangian density has been constructed and SUSY Dyonic solutions have been obtained. Furthermore, the classical mass of the Dyon has been calculated by minimizing the background potential of theory. The eigen value equations of bosonic and fermionic fluctuations have been obtained in the dyonic background gauge and the corresponding one-loop corrections to the Dyonic mass are calculated and it has been shown that one-loop quantum corrections lead no change in classical mass of Dyon.

25 ref

023894   Rajendra Kumar;Singh S;Mishra A K (Physics Dep, Allenhouse Institute of Technology, Rooma, Kanpur-208 008, Email: rajendra_ks@rediffmail.com) : Electrical, optical and structural characterization of polyaniline thin film prepared by pulsed-plasma polymerization. J Polym Mater 2010, 27(4), 359-67.

The pulsed-plasma polymerization technique has been use to prepare the polyaniline (PANI) thin film. The effects of substrate position, pressure and number of plasma pulses on the film growth rate were monitored and established ideal conditions. The structural and optical behaviors of the PANI thin film were characterized using UV-vis, FTIR and optical absorption spectra. The electrical conductivity measurements were also carried out at different conditions.

6 illus, 2 tables, 16 ref

023893   Joshi L K;Burghate D K;Barde W S;Deshmukh S H;Asole A W;Shilaskar S N (NO, Shri Shivaji Science College, Amravati, Email: sharma.lakshmi0@gmail.com) : Impedance analysis and dielectric relaxation study in polyaniline doped PVC-PS Blend. Vidarbha J Sci 2011, 6(1-2), 46-52.

The polyblend of polyvinyl chloride (PVC) and polystyrene (PS), in the weight ratio 5 : 1 were prepared by using 1.25 gm of PVC and 0.25 gm of PS. Polyaniline (PAN1) has been used as dopant with 2.5 % of the total weight of the two polymers. The ac conductivity and dielectric constant of polyaniline doped PVC-PS thin films have been investigated in the temperature range 313 K - 353 K and in the frequency range 0.5 KHz - 200 KHz. Impedance plots were used as tools to analyse the sample behaviour as a function of frequency and temperature.

7 illus, 2 tables, 24 ref

023892   Gawande W J;Yawale S S;Yawale S P (Physics Dep, Govt. Vidarbha Institute of Science and Humanities, Amravati) : Hopping conduction mechanism in amorphous CuO-Bi₂O₃ semiconducting pellets. Vidarbha J Sci 2011, 6(1-2), 20-4.

The results of measurement of dc-eiectrical conductivity and activation energy have been reported for four different composition of CuO-Bi₂O, glass powder pellets pressed at 50°C in the temperature range of 300 - 493 K. A plot of - log σ versus I/T shows two different regions of conduction suggesting two types of conduction mechanisms switching from one type to another occurring at knee temperature. The de-conductivity increases with increase in temperature of the sample and also with increase of mol% of CuO. Activation energy calculated for both regions (LTR and HTR) is below 1 eV, thus the electrical conduction is electronic. Activation energy decreases with increase of mol% of CuO. Non-adiabatic hopping conduction was observed in the sample.

4 illus, 17 ref

023891   Athawale A A;Majumdar M;Singh H;Navinkiran K (NO, Univ of Pune, Pune-411 007, Email: agbed@chem.unipune.ernet.in) : Synthesis of cobalt oxide nanoparticles/fibres in alcoholic medium using gamma-ray technique. Def Sci J 2010, 60(5), 507-13.

Nanoparticles of cobalt oxides were synthesised by steady state γ irradiation technique using various alcoholic salt solutions of cobalt ions with aniline acting as a stabiliser. Preliminary results were investigated using UV-vis and Fourier transform infra red analysis. The X-ray diffractograms revealed major peaks at 28 values of <126> 36.4°, 39.1°, 44.2°, and 65.7° corresponding to the Co₃O₄phase and one peak at <126>30.7° (100 per cent intensity) for Co₂O₃ phase. Lower alcohols yielded particles while fibres were formed in higher alcohols as observed from transmission electron microscopic analysis. Iso-propanol was observed to yield cobalt oxide nanoparticles with highest stability, conversion yield and homogeneity in size. The average measured diameter and length of these fibres were <126>29 nm and 130 nm respectively. Energy dispersive spectroscopy supports the formation of cobalt oxide. The X-ray photoelectron spectroscopic results for iso-propanol sample show a peak at 781.6 eV confirming the formation of Co₃ O₄.

6 illus, 1 table, 27 ref

009510   Yoshida A;Uchida M;Ishizaka M;Wakahara A (Department of Electical and Electonic Engineering, Toyohashi University of Technology, Tenpaku, Toyohashi,444-8580, Japan) : Micromachining and microdeposition of polytetrafluoroethylene by synchrotron radiation. J Indian Inst Sci 2001, 81(5), 569-71.

^ssc3 illus, 7 ref

009509   Wakahara A;Nakanishi Y;Ohshima T;Itoh H (Department of Electrical and Electronics Engineering, Toyohashi University of Technology, Toyohashi-441-8580, Japan) : Luminescence properties of Eu-implanted GaN for full color micro light-emitting diode array. J Indian Inst Sci 2001, 81(5), 579-83.

^ssc6 illus, 1 table, 10 ref

009508   Upadhyay M M;Ubale S K;Adgaonkar C S (NO, Institute of Science, Nagpur-440 001) : Study of electrical properties of glass thermoelectret. Indian J Engng Mater Sci 2003, 10(2), 169-72.

Thermoelectrets were prepared by applying different polarizing fields at different polarizing temperatures to the glass of composition [50ZnO-50B₂O₃]. The dc conductivity, dielectric constant and ac conductivity of these glass electrets were measured and the properties were found to be influenced by the polarizing field as well as temperature.

3 illus, 17 ref

009507   Subramanyam T K;Venkata Rao G;Ramakrishna Reddy K T;Uthanna S (NO, Technical University of Munchen, Munchen 80290, Germany) : Effect of sputtering pressure on the physical properties of dc magnetron sputtered cadmium oxide films. Indian J Engng Mater Sci 2003, 10(2), 151-4.

Polycrystalline thin films of cadium oxide were prepared using dc magnetron sputtering technique by sputtering of metallic cadmium target in the mixture of argon and oxygen atmosphere under various sputtering pressures in the range 3x10^-2-1x10^-1 mbar. The variation of deposition rate of the films with the sputtering pressure was in correlation with the variation of cathode potential. The influence of sputtering pressure on the structural, electrical and optical properties of CdO films was systematically studied. The electrical resistivity of the films increased from 5.6x10^-4 to 1.5x10^-3 Ωcm and the optical band gap increased form 2.45 to 2.53 eV with the increase of sputtering pressure from 3x10^-2 to 1x10^-1 mbar respectively.

6 illus, 20 ref

009506   Singh A V;Manjo Kumar;Mehra R M;Wakahara A; Yoshida A (Electron Sci Dep, University of Delhi, South Campus, New Delhi-110 021) : Al-doped zinc oxide (ZNO:Al) thin films by pulsed laser. J Indian Inst Sci 2001, 81(5), 527-33.

Highly conductive and transparent aluminum-doped zinc oxide thin films were prepared by ablating the target continiing 2 wt per cent Al₂O₃ with ArF excimer laser (λ=193 nm). The films were grown at a repetition rate of 10 Hz, energy density of 2-3 J/cm² and irradiation time of 10-60 min (6000-36000 laser shots). the optical and electrical properties of the films depend on the substrate temperature and oxygen pressure during film deposition. The lowest resistivity was found to be at 1.44 87cm for films deposited at 300°C and in 1 mtorr of oxygenambient. The average transmittance was found to be in the range of 84-92 per cent. sharp decrease in transmittance and sharp increase in reflectance near the plasma edge in the near-infrared range are due to impurity scattering, which is caused by aluminum doping.

8 illus, 28 ref

009505   Saxena Y C (Institute for Plasma Research, Bhat, Gandhinagar - 382 428) : Tokamak SST-1 : An over-view. Bull Indian Vacuum Soc 2002, 5(4), 5-8.

3 ref.

009504   Ravi Kumar A B;Uthanna S;Srinivasulu Naidu B; Sreedhara Reddy P (Phys Dep, Sri Venkateswara Univerity, Tirupati-517 502) : Effect of oxygen partial pressure on the optical properties of DC magnetron sputtered TiO₂ films. J Indian Inst Sci 2001, 81(5), 573-7.

Titanium oxide (TiO₂) thin films were deposited by DC magnetron sputtering of titanium target at various oxygen partial pressures in the range 1 x 10⁴-5 x 10^-3 mbar and at a constant substrate temperature of 573 K. Good-quality TiO₂ films were obtained at an oxygen partial pressure of 8 x 10⁴ mbar.

^ssc6 illus, 1 table

009503   Pathak H A et al (Institute for Plasma Research, Bhat, Gandhinagar - 382 428) : Critical design and fabrication issues related to SST-1 vacuum system. Bull Indian Vacuum Soc 2002, 5(4), 9-18.

Describes critical issues related to the design and fabrication of different components of SST-1 vacuum system. Also, the results of test experiments carried out to establish the process to achieve functional requirements are presented.

8 illus, 2 tables, 5 ref.

009502   Nishio M;Hayashida K;Tanaka T;Guo Q;Ogawa H (Department of Electrical and Electronic Engineering, Saga University, Saga-840 8502, Japan) : Study of novel nonthermal epitaxial technique of compound semiconductor using synchrotron radiation. J Indian Inst Sci 2001, 81(5), 549-55.

ZnTe homoepitaxial growth has been investigated at room temperature using synchrotron radiation. Growth characteristics of the film such as thickness distribution and source transport rate dependence of the growth rate have been studied as also the effect of diethyltelluride/diethylzinc gas composition on the photoluminescence spectrum of the film. a sharply excitonic emission at 2.375 eV associated with shallow acceptors is observed and neither a donor-acceptor pair recombination nor a deep-lvel luminescence signal is detected in the spectrum of the film grown under nearly stoichiometric condition, which indicates that ZnTe films of good quality can be grown even at room temperature by this growth technique. Discusses the relationship between substrate temperature and photoluminescence spectrum of the film in relation to actual VI/II ratio near the growing surface.

5 illus, 1 table, 38 ref

009501   Mitra S;Mukhopadhyay (Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : Molecular dynamics using quasielastic neutron scattering. Curr Sci 2003, 84(5), 653-62.

Quasielastic neutron scattering (QENS) technique is well suited to study the molecular motions (rotations and translations) in solids or liquids. It offers a unique possibility of analysing spatial dimensions of atomic or molecular processes in their development over time. Some of the systems studied using the QENS spectrometer, designed, developed and commissioned at Dhruva reactor in Trombay. A variety of systems have been studied to investigate the molecular motion, for example, simple molecular solids, molecules adsorbed in confined medium like porous systems or zeolites, monolayer-protected nanosized metal clusters, water in Portland cement as it cures with time, etc.

14 Illus, 2 Tables, 22 Ref

009500   Misra S C K;Bhattacharya R;Angelucct R (Polymer Electronics Division, National Physical Laboratory, New Delhi-110 012) : Integrated polymer thin film macroporous silicon microsystems. J Indian Inst Sci 2001, 81(5), 563-7.

^ssc5 illus, 3 ref

009499   Mathe V L;Bhosale C H (Physics Dep, Shivaji University, Kolhapur-416 004) : Effect of annealing on spray deposited Ni-Zn ferrite thin films. Indian J Engng Mater Sci 2003, 10(2), 166-8.

The thin films of Ni-Zn ferrite have been synthesized using spray pyrolysis technique onto the glass substrate. These deposited films are found to be amorphous and the films become crystalline after annealing them in the temperature range 400-600°C in the steps of 100°C for 6 h. It is found that the cyrstallinity increases with annealing temperature. Further, for the film annealed at 600°C, some additional XRD peaks of the glass substrate have been observed. Therefore, the films annealed at 500°C are characterized further by EDAX technique. The elemental analysis by EDAX confirms the stoichiometric formation of Ni-Zn ferrite. The resistivity for all the samples with respect to temperature shows rapid decrease in resistivity at around 180°C. This may be due to oxido-reduction process that appears during heating of ferrite sample in the air. 3Fe²⁺↔2Fe³⁺ total reaction takes place in the temperature range 100-250°C. However, there is no much difference in the resistivity value at room temperature for these samples.

^ssc4 illus, 1 table, 5 ref

009498   Goswami D K;Satpati B;Satyam P V;Dev B N (NO, Inst of Physics, Sachivalaya Marg, Bhubaneswar-751 005) : Growth of self-assembled nanostructures by molecular beam epitaxy. Curr Sci 2003, 84(7), 903-10.

A compact, custom-made molecular beam epitaxy (MBE) system has been installed and a commercial ultrahigh vacuum scanning tunnelling microscope (STM) has been coupled to the MBE chamber. Examples of growth of self-assembled nanostructures by MBE using this system and characterizations using reflection high energy electron diffraction, STM and high resolution transmission electron microscopy are presented.

8 Illus, 38 Ref

009497   Chenna Reddy D;Chaudhuri P;Santra P; Khirwadkar S;Ramesh Babu G;Ravi Prakash N;Arun Prakash A;Saxena Y C (Institute for Plasma Research, Bhat, Ghandhinagar - 382 428) : SST-1 first wall : design for UHV compatibility. Bull Indian Vacuum Soc 2002, 5(4), 21-9.

Describes the materials, design and fabrication aspects of the first wall in some detail to emphasize how the UHV requirement is met in SST-1.

7 illus, 2 tables, 8 ref.

009496   Chakraborty S;Bhattacharya S K (Physical Res Lab, , Ahmedabad 380 009) : Mass-independent isotopic fractionation: Recent developments. Curr Sci 2003, 84(6), 766-74.

It has been about three decades since the discovery of anomalous (mass-independent) oxygen isotopic composition in meteoritic materials. Since then, mass-independent oxygen isotopic compositions have been observed in a number of stratospheric species like ozone. A significant amount of experimental as well as theoritical work has been carried out to understand the origin of mass-independent fractionation. In recent years, there has been notable progress through precise stratospheric observations, new kinds of laboratory experiments and theoritical models. Recent developments in this field of research have been presented.

5 Illus, 1 Table, 65 Ref

008414   Yurtseven H;Pitirli O E (Physics Dep, Istanbul Technical University, Maslak, Istanbul, Turkey) : Lambda-phase transition in liquid sulfur. Indian J Phys-Pt B 2002, 76(6), 723-6.

The study examines the second Pippard relation near the λ-phase transition in liquid sulfur (T_λ = 159°C). Obtains a linear variation of the thermal expansivity with the isothermal compressibility below T_λ and obtains a curve above T_λ by using the literature data for the system. The value of the slope (dP/dT)_λ from the plot below T_λ is close to the literature value obtained from a specific heat versus thermal expansivity (first Pippard relation). This indicates that the Pippard relations are valid below the λ point for the sulfur system exhibiting the λ-type of phase transition. Above T_λ in the temperature interval of <126>160°C <60>T <60>170°C, the slope (dP/dT)_λ enlarges significantly which indicates that the second Pippard relation is not valid.

1 illus, 20 ref

008413   Varghese T;Balakrishna K M;Siddappa K (Physics Dep, Nirmala College, Muvattupuzha-686 661, Kerala) : Compton profile of samarium. Indian J Phys-Pt B 2002, 76(5), 657-9.

The Compton profile of Sm has been measured using IGP Type Coaxial photon detector. The target atoms were excited by means of 59.54 KeV gamma rays from Am-241 radioactive source of strength 300 mCi. Elemental foil of uniform aerial density and purity better than 99.9% was used as target. The data were recorded and analyzed using a 4K multichannel analyzer. The present experimental Compton profiles of Sm constitute the first measurement. The results are compared with theoretical Hartree-Fock free-atom profiles.

1 illus, 1 table, 10 ref

008412   Uthanna S;Mohan Babu P;Naidu B S (Physics Dep, Sri Venkateswara University, Tirupati - 517 502) : DC magnetron sputtering of cadmium-indium alloy: Physical properties of cadmium indate films. J Instrum Soc India 2002, 32(1), 9-15.

Deals with the dc magnetron sputtering of cadmium-indium alloy target in oxygen and argon atmosphere. The dependence of cathode potential on the oxygen partial pressure was explained in terms of cathode oxidation effect. Transparent conducting cadmium indate films were deposited by sputtering of cadmium-indium alloy target onto glass substrates held at a temperature of 523 K under various oxygen partial pressures in the range 1 x 10^-4-5 x 10^-3 mbar. The influence of oxygen partial pressure on the electrical and optical properties was studied and the results were reported.

6 illus, 12 ref

008411   Singh P P;Saxena S (Physics Dep, S R M S College of Engg & Tech, Bareilly-243 202) : Coherence in positron (electron) scattering by lithium atoms. Indian J Phys-Pt B 2002, 76(5), 643-8.

The study of alignment and orientation parameters provides complementary information on the anisotropic charge cloud distribution (alignment) and the rotation of atomic excited state (orientation), which is not available from the measurement of differential and total cross sections alone. A two potential approach is used to study these parameters in the positron (electron) impact 2s-3p excitation of lithium atom. Results are obtained for the angular variation of the angular momentum transfer (L₁), the polarization components (P₁, P₂), linear polarization (P_l), polarization <124>P<124> and the alignment angle (γ at impact energies of 20 eV and 30 eV. Comparison with the corresponding parameters in electron scattering is made to see the role of various interaction potentials in the process. It is found that for this transition, a significant change appears in between positron and electron impact excitation.

4 illus, 1 table, 15 ref

008410   Shrivastava P;Shrivastava P K (NO, Government New Science College, Rewa-486 001) : Comparative study of Forbush decrease events of February and August, 1999. Indian J Phys-Pt B 2002, 76(6), 699-703.

Forbush decrease in cosmic ray intensity shows a sudden decrease in count rates of neutrons followed by a slow recovery, typically lasting for several days. Two such Forbush decrease events noted first in August 19 to 29, 1999 and another in February 15 to 23 1999 occurred during a high solar activity period in 1999. It is noteworthy that both the events were accompanied with several intense solar flares and geomagnetic storms. Makes a comparative analysis of the characteristics and production mechanisms of the events. Further, finds out a significant correlation between cosmic ray intensity variation and geomagnetic activity index Dst. Decrease in Dst values shows a similar pattern of cosmic ray decreases, indicating a strong relationship between the two. Results of analysis also suggest a strong relationship between geomagnetic activity and cosmic ray intensity variation on short-term basis.

4 illus, 1 table, 10 ref

008409   Shetty B J;Krishnakumar S;Balasubramanian T K (Spectroscopy Div, Modular Lab, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085) : Vibrational structure in the E<. Indian J Phys-Pt B 2002, 76(6), 743-5.

The (gas phase) electronic spectrum of the germanium monosulphide (GeS) molecule is characterized by two prominent transitions. The emission bands of the weaker of the two systems, assigned as E¹Σ⁺-X¹Σ⁺, presumably, occur in two distinct groups, one in the ultraviolet (220-270 nm) and the other in the visible (450-650 nm) sharing this peculiarity with the E-X bands in the isovalent molecules SiO, SiS, SiSe, GeO etc. The vibrational structure in the E-X transition of GeS is examined by studying the spectra due to the specific isotopomers ⁷⁰GeS and ⁷⁴GeS, excited (separately) in electrodeless discharge lamps. The isotopically pure spectrum enabled assignment of vibrational numbering for the bands in the ultraviolet and visible regions. Since the experimental uncertainties in the band head measurements are rather large, particularly for the ultraviolet bands, some ambiguities may still persist in the vibrational assignments. An additional complication arises from the near equality of the vibraitonal quanta in the lower (X¹Σ⁺) state with the double quanta in the upper state for intermediate v', v" values. The result is that the band with a given (v', v") assignment overlaps with the band assigned as (v'+2, v"+1). Such overlapping band heads happen to show similar isotope shifts and hence become prone for multiple assignments.

1 table, 12 ref

008408   Sharma A K;Parashar J (Centre for Energy Studies, Indian Institute of Technology, Hauz Khas, New Delhi-110 016) : Langmuir wave excitation and charged particle acceleration by a millimeter wave. Curr Sci 2003, 84(3), 425-8.

In the presence of a magnetic wiggler, a high power millimetre (mm) wave propagating through a magnetized plasma of density close to critical, excites a large amplitude Langmuir wave. The amplitude of the Langmuir wave shows resonant enhancement around cyclotron resonance, however, the wiggler period required to produce large phase velocity Langmuir waves approaches to impractically small values near resonance. As a compromise, one could choose ω_L/ω_c ≈ 0.7 for optimal excitation of Langmuir waves, where ω_L and ω_c are the mm wave and electron cyclotron frequencies respectively. The amplitude of the Langmuir wave attains saturation by relativistic effects. For a 36 GHz wave with 1 MW/cm² power density, the field of the Langmuir wave for optimum parameters turns out to be <62> 30 MV/m. The Langmuir wave can be employed to accelerate electrons. The acceleration length however, scales inversely with the frequency of the mm wave.

2 illus, 12 ref

008407   Sen N (NO, , 1333 Poorvanchal Complex, J.N.U. New Campus, New Delhi-110 067) : Sensitive flow sensors with carbon nanotubes. Curr Sci 2003, 84(3), 269-70.

^ssc2 illus, 5 ref

008406   Sasidhar N;Mallikarjunaiah K J;Damle R (Physics Dep, Jnana Bharathi, Bangalore University, Bangalore - 560 056) : Modulation schemes of wide-line NMR absorption. J Instrum Soc India 2002, 32(1), 1-8.

Describes the use of different types of modulation and detection schemes to observe nuclear resonance in bulk materials. The most convenient and popularly employed modulation and detection scheme is the magnetic field modulation with linear variation of the strength of the static magnetic field to observe resonance absorption. Also tried other uncommon modulation and detection schemes to record the absorption signal in a standard sample of glycerine. These methods leads to the first derivative signal when a phase sensitive detection is used to improve the signal to noise ratio. The limitations of the schemes have been highlighted.

5 illus, 6 ref

008405   Rashid M H;Bhandari R K (NO, Variable Energy Cyclotron Centre (DAE), Sector-1, Block-AF, Salt Lake, Kolkata-700 064) : Loss cone profile on the imaginary surface just enclosing the resonance surface in 14.4 GHz ECR ion source. Indian J Phys-Pt B 2002, 76(5), 669-72.

A 14.4 GHz ECR ion source was designed recently for the superconducting cyclotron. The concept of local mirror ratio at a point has been defined. A relationship between mirror ratio and the loss cone is deduced. The mirror ratio giving the loss cone profile on the surface of an imaginary box just enclosing the resonance surface (assumed plasma volume) are evaluated. Electron reflection and loss is discussed in the plasma chamber.

7 illus, 6 ref

008404   Rajesh R J;Jose M;Bisht P B (Physics Dep, Indian Institute of Technology Madras, Chennai-600 036) : Diffraction efficiency of transient grating and relaxation profiles of some laser dyes. Indian J Phys-Pt B 2002, 76(6), 737-42.

Self-diffraction efficiency of laser dyes have been measured and compared with theoretical values for some dyes. Effect of refractive index of the solvent on the diffraction efficiency has also been studied. Degenerate four wave mixing have been used to measure the excited state relaxation profiles to estimate the orientational relaxation times in ps time scale.

6 illus, 24 ref

008403   Rahaman F;Chakraborty S;Hossain M;Begum N; Bera J (NO, , Khodar Bazar, Baruipur-743 302, 24 Parganas (South), West Bengal) : Higher dimensional string cosmology in Lyra geometry. Indian J Phys-Pt B 2002, 76(6), 747-51.

Some cosmological solutions for string model are derived in higher dimensional spherically symmetric space time based on Lyra's geometry. The physical behaviour of the models is also discussed.

8 ref

008402   Pandey R P;Singh K M;Karim S M;Misra K D; Pandey R S (Physics Dep, Veer Kunwar Singh Uiversity, Ara-802 301) : Current-driven oblique whistler mode by cold plasma injection in the magnetosphere of Uranus. Indian J Phys-Pt B 2002, 76(5), 619-25.

The effect of cold plasma injection on oblique whistler mode wave in the presence of a perpendicular AC field in a background plasma having a bi-Maxwellian and also a loss-cone distribution function has been examined separately in the magnetosphere of Uranus. In both the cases the effect of cold plasma injection and other plasma parameters have bene compared. It is found that the magnitude of the AC field has almost no effect on the growth rate or on the real frequency of the wave. But the growth rate increases with the increase of AC field frequency. For loss-cone background, the growth rate increases by more than an order of magnitude in comparison to bi-Maxwellian background. Increase of temperature anisotropy also increases the growth rate, thus the source of free energy for this instability is not only the temperature anisotropy but also the AC field frequency. There is marginal effect on the growth rate with increase of the angle of incidence and drift velocity of the electrons, but increase in the ratio of cold injected plasma to background plasma (n_c/n_w) reduces the growth rate. In all the cases there is no change in the value of the real frequency for all other plasma parameters suited to the magnetosphere of Uranas. But in case such a situation as mentioned, exists in the magnetosphere, it may give rise to emissions over a broad frequency range and would be more appropriate for explaining the entire frequency spectrum of VLF emissions.

6 illus, 9 ref

008401   Nazakai Ullah (NO, Tata Institute of Fundamental Research, Colaba, Mumbai-400 005) : Effect of impurity on the ground state of a system in a solvable three dimensional model. Indian J Phys-Pt B 2002, 76(6), 753-5.

The effect of impurity on a quantum system is studied using a solvable model. Expressions have been derived for the probability density function of the ground state energy and the spacing. The spacing distribution shows a very interesting behaviour which could be compared with experiments.

3 ref

008400   Mukherjee P;Gupta B (Electronics and Telecommunication Engineering Dep, Institute of Engineering & Management, Salt Lake Electronic Complex, Kolkata-700 091) : Genetic algorithm based optimization for impedance bandwidth of microstrip patch antenna. Indian J Phys-Pt B 2002, 76(6), 727-30.

In spite of its numerous advantages like small size, light weight, conformability etc, one of the disadvantages of microstrip antennas is that they are very narrowband in nature, typically <60>1% of the center frequency. Investigations have been made on the effect of aspect ratio and feed location for the coaxial back feed on the VSWR bandwidth of the patch antenna. Without any additional matching network, optimal impedance matching of the antenna with a single common feed line has been achieved using genetic algorithm. The investigation is made at different microwave frequency bands and it is found that the optimum 2 : 1 VSWR ranges up to <126>7% of the center frequency of operation, gradually increasing for higher frequency bands.

2 illus, 4 ref

008399   Hashim I (School of Mathematicsl Sciences, Faculty of Science and Technology, National University of Malaysia, 43600 UKM Bangi, Selangor, Malaysia) : On the short-wave Benard-Marangoni stability of a fluid layer with surface deformation. Indian J Phys-Pt B 2002, 76(5), 605-7.

An analytical description of the marginal stability curve for the onset of oscillatory Benard-Marangoni convection in a horizontal fluid layer bounded above by a deformable free surface and bounded below by a thermally conducting planar boundary in the asymptotic limit of short waves is obtained.

5 ref

008398   Dastidar K R (Spectroscopy Dep, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700 032) : New, non-local quantum electrodynamics: its effect on multiphoton single and double ionization. Indian J Phys-Pt B 2002, 76(5), 635-41.

By considering a new, non-local quantum electrodynamics, it is shown that the non-sequential double ionization of atoms occur due to the phase correlated two-photon excitation of electrons. For this phase correlated excitation, two-photon rate depends linearly on laser intensity. However, the local nature of the radiation field gives rise to conventional multiphoton transitions, where the two-photon rate is proportional to the square of the laser intensity. Shows that n-photon transitions in an experiment can be modeled as a series of these two types of transitions and hence several channels will run parallel to each other. The channels for n-photon transitions are (i) a series of phase correlated transitions giving rise to non-sequential double ionization, (ii) a series of conventional dipole transitions giving rise to sequential ionization and (iii) a mixture of phase correlated and phase non-correlated transitions. Also shows that, with the increase in laser intensity the channel comprising of only the phase correlated excitations becomes significant and gets saturated before the sequential channel can dominate, giving rise to a kink-like structure in the intensity variation of double ionization. This feature has been observed in the experiments on double ionization of He.

4 illus, 13 ref

008397   Das T K;Sarkar H (Centre for Advanced Studies in Microwave & Millimeterwave Technology, Institute of Radio Physics & Electronics, 92, A.P.C. Road, Kolkata-700 009) : Spectral study on solar radio bursts in the microwave-millimeterwave transition. Indian J Phys-Pt B 2002, 76(5), 615-8.

In order to evaluate the spectra of solar radio bursts in the microwave-millimeterwave transition region, the multifrequency burst data of Berne observatory have been used. The bursts give spectral nature which resemble inverted-U (IU), increasing (I), decreasing (D), U and Zigzag types. The spectral peak of these spectra occur at 11.8 GHz in most of the cases. The directivity and optical thickness of the absorbing layer above the source of bursts are determined. The results are discussed in the light of the different emission and absorption mechanisms responsible for the generation of radio bursts.

3 illus, 20 ref

008396   Choudhary D P;Ambastha A K;Murali K R;Vashant Kumar N G (NO, Udaipur Solar Observatory/PRL, Udaipur-331 001, Rajasthan) : No evidence of circumsolar dust ring during solar activity minimum phase. Indian J Phys-Pt B 2002, 76(5), 609-13.

A circumsolar dust ring is believed to be situated at 4 R and temporally variable in anti-phase with the solar activity cycle. The observable signatures of such a ring is : (i) its thermal radiation in near IR and (ii) a highly polarised scattered solar radiation by the ring constituents. During the past attempts the ring signatures were mostly observed at the time of the solar activity minimum phase. Extensive observations at the time of 1991 total solar eclipse did not show any signature of the circumsolar dust ring. The 1995 total solar exlipse in India provided a unique opportunity to test the "solar activity dependence" hypothesis for the existence of the dust ring. A computer-controlled, laboratory calibrated, wide-field imaging polarimeter was designed to make measurements through three filters centred at 6500, 8100 and 9500 Å for detecting the ring signature. The polarimeter was calibrated using various laboratory test facilities at Space Application Centre. The experiment was carried out at Kalpi, UP during the 24 October 1995 total solar eclipse. The observed coronal polarization and surface brightness were found to be consistent with the overall expected corona at the solar minimum phase. It has been reported that no ring signature was observed by the experiment and conclude that the circumsolar dust ring might be a temporary feature.

5 illus, 10 ref

008395   Chattopadhyay R;Midya S K (NO, Haripal G.D. Institution, Khamarchandi-712 405, Hooghly) : Latitudinal variation of OI 6300 Å line intensity reviewed in the light of Barbier's equation. Indian J Phys-Pt B 2002, 76(5), 627-34.

Latitudinal variation of OI 6300 Å line intensity has been computed and a least square fitted curve has been obtained for the same. OI6300 Å line-intensity, as observed at Narendrapur (Lat. 22°35'N, long. 88°21'E) during the period 1984-1986 has been compared with the values of the same quantity obtained from empirical relation as given in Barbier's equation using ionospheric paramters h'F and f_oF₂ at Ahmedabad (Lat. 23°01'N, long 72°36'E) for the same period. The correlation coefficient between them has been calculated and is found to be of sufficiently high values. An empirical equaiton relating the two above mentioned variables has been established. Similarly using the ionispheric parameters f_oF₂ and h'F of Kodaikanal (Lat. 10°44'N, long. 77°29'E) station the corresponding OI 6300 Å line intensity for each month for the period 1984-1986 has been computed using the Barbier's empirical relation. This curve is again compared with the corresponding values of the same parameter obtained separately from the latitudinal variation-fitting equation and the corresponding values of OI 6300 Å line intensity at Narendrapur. Except at a few portions both the curves has been found to compare well with each other.

4 illus, 34 ref

008394   Chandra S (School of Physical Sciences, S R T M University, Nanded-431 606) : Einstein A-coefficients for rotational transitions in the ground vibrational state of Si₂C molecule. Indian J Phys-Pt B 2002, 76(5), 649-55.

Calculates Einstein A-coefficients for rotational transitions in the ground vibrational state of the Si₂C molecule between the rotational energy levels up to 21 cm^-1. The coefficients are used to calculate the mean radiative lifetime of the levels. These A-coefficients may be used as input parameters for analyzing the spectra of Si₂C as and when it would be observed in an astronomical object. The transitions 7₀₇→6₁₆(5.34 GHz) and 8₀₈→7₁₇(14.74 GHz) may play important role for the search of the Si₂C molecule in astronomical objects.

1 illus, 10 tables, 21 ref

008393   Chakrabarti S K;Pal S;Acharya K;Mandal S; Chakrabarti S;Khan R;Bose B (NO, S.N. Bose National Centre for Basic Sciences, JD-Block, Salt Lake, Kolkata-700 098) : VLF observation during Leonid meteor shower-2002 from Kolkata, India. Indian J Phys-Pt B 2002, 76(6), 693-7.

Using a Gyrator-II Loop antenna tuned at 19.0 KHz, monitored the meteor shower during 17-24th November, 2002. Observed the primary peak at 3h58m (UT) on the 19th of November, 2002. Also observed several `beadlike' and `exponentially dropping' signals. The `beadlike' signals were more in abundance on the 18th of November, 2002, one day prior to the actual encounter.

3 illus, 13 ref