Indian Journal of Pure and Applied Physics

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Volume 44                                                   Number 12                    DECEMBER 2006

                                                                   

CODEN: IJOPAU 44(12) 881-978                                                        ISSN: 0019-5596                               

 

 

 

CONTENTS

 







Atomic and Molecular Physics

 

Spectral analysis of Cu2+: B2O3-(TeO2/CdO/ZnO)-Li2O-AlF3 glasses

B Sudhakar Reddy & S Buddhudu*

887

Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics and Fluid Dynamics

 

Holographic optical elements encoded security holograms with enhanced features

Sushil K Kaura, S P S Virdi  & A K Aggarwal*

896

Determination of stability constants of charge transfer complexes of iodine monochloride and certain ethers in solution at 303 K by ultrasonic method

V Kannappan*, S J Askar Ali & P A Abdul Mahaboob

903

Ultrasonic velocities and refractive indices of binary mixtures of propylene carbonate+n-alkanols

D S Wankhede, N N Wankhede, M K Lande & B R Arbad*

909

Physics of Gases, Plasmas and Electric Discharges

 

Generation of kinetic Alfven wave by velocity shear in the plasma sheet boundary layer during substorm

B V Tiwari, Ruchi Mishra, P Varma & M S Tiwari*

917

Reflectivity of low energy photons from one and two dimensional rare hot quantum and classical plasmas

S P Tewari* & Jyoti Sood

927

Condensed Matter: Structure, Mechanical and Thermal Properties

 

Cation distribution in mixed Mg-Mn ferrite systems from X-ray diffraction technique and saturation magnetization

Gagan Kumar, Meenakshi Kanthwal, B S Chauhan & M Singh*

930

Compensation effect of ac conduction in Se80Te20 and Se80Te10M10 (M = Cd, In, Sb) chalcogenide glasses

N Mehta, D Kumar & A Kumar*

935

Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties

 

Molecular associations in binary mixture of pyridine and N, N-dimethylacetamide in benzene solution using microwave absorption data

Sandeep Kumar*, D R Sharma, N Thakur, N S Negi & VS Rangra

939

Study of dielectric relaxation and dipole moment of some hydrogen bonded solvent binary mixtures in 1,4-dioxane

R J Sengwa*, Madhvi, Abhilasha & Sonu Sankhla

943

Interdisciplinary Physics and Related Areas of Science and Technology

 

Temperature, current and doping dependence of non-ideality factor for pnp and npn punch-through structures

Khurshed Ahmad Shah* & S S Islam

953

Announcement

963

Annual Author Index

964

Annual Keyword Index

970

List of experts

978

 

___________

*The corresponding author has been indicated by (*) mark in case of papers with more than one author.


Indian Journal of Pure & Applied Physics

Vol. 44, December 2006, pp. 887-895

 

 

Spectral analysis of Cu2+: B2O3-(TeO2/CdO/ZnO)-Li2O-AlF3 glasses

B Sudhakar Reddy & S Buddhudu*

Department of Physics, Sri Venkateswara University, Tirupati 517 502

*E-mail: sudhakar_b9@rediffmail.com

Received 29 September 2006; accepted 20 October 2006

The development and optical spectral analysis of Cu2+ (0.5 mol %) doped three new glasses have been reported in the following composition: 10TeO2-69.5 B2O3-10 Li2O-10 AlF3; 10CdO-69.5 B2O3-10 Li2O-10 AlF3; 10ZnO-69.5 B2O3-10 Li2O-10 AlF3. Due to the homogeneous distribution of Cu2+ ions, both CdO and ZnO containing glasses are found to be in bright blue colour, but a greenish blue colour has been noticed from the TeO2 containing glass, the reason for this has been explained. Without the Cu2+ ions, the reference glasses have also been prepared and found them in good transparency with excellent resistance towards the moisture without any degradation on their surfaces. Based on the XRD profiles, amorphous nature of these glasses has been confirmed. Due to the presence of TeO2, the UV transmission for the glass is found to be extended up to 300 nm compared with the other two glasses. Under an UV source (254 nm), a blue emission has been noticed from the surfaces of the glasses. From the measured absorption spectra of these copper glasses, a abroad absorption band (2B1g2B2g) at 800 nm and a weak absorption band (2B1g2Eg) at 387 nm have been measured to examine the effects of the CdO, ZnO and TeO2 contents in the glasses studied. FTIR spectra of these glasses have also been analyzed to investigate the glass structures. Emission spectra of (0.5 mol %) Cu2+: B2O3-(TeO2/CdO/ZnO)-Li2O-AlF3 have revealed two emissions at 415 and 438 nm with an excitation at 371nm.

Keywords: Copper glasses, Optical analysis, Spectral analysis, Absorption band

IPC Code: GO1J3/28

Indian Journal of Pure & Applied Physics

Vol. 44, December 2006, pp. 896-902

 

Holographic optical elements encoded security holograms with enhanced features

 

Sushil K Kaura*, S P S Virdi # & A K Aggarwal

Coherent Optics Division, Central Scientific Instruments Organisation, Chandiigarh 160 030

*E-mail: skkaura_22 @ rediffmail.com

#Physics Department, Punjabi University, Patiala 147 002

Received 3 August 2006; accepted 10 October 2006

A simple and cost-effective two-step method for forming encoded security holograms with enhanced features is described in this paper. These security holograms contain enhanced encoded/concealed anti-counterfeit security features, which can only be decoded using a key hologram in the final reading process. The encoded key hologram and the security hologram are in the form of special encoded complex holographic optical elements. When the security hologram is illuminated with the decoding beam, specific moiré-like fringe patterns are formed on the security hologram and in addition several spatially separated bright focused spots are also generated from the security hologram. A careful spatial filtering of these bright spots results in specific moiré patterns at different locations in the observation plane and moreover these patterns contain variable interferometric features. Further, these moiré patterns disappear when the security hologram is perfectly repositioned and only the variable interferometric features are formed. Since these security holograms contain variable interferometric features in addition to the specific moiré patterns and bright focused spots, thus making these holograms suitable for both visual and as well as machine inspection.

Keywords:   Security holograms, Holographic optical elements encoded holograms, Concealed coded holograms, Optical security

IPC Code:   G03H

 

Indian Journal of Pure & Applied Physics

Vol. 44, December 2006, pp. 903-908

 

Determination of stability constants of charge transfer complexes of
iodine monochloride and certain ethers in solution at 303 K by ultrasonic method

V Kannappan, S J Askar Ali & P A Abdul Mahaboob

Postgraduate and Research Department of Chemistry, Presidency College (Autonomous), Chennai 600 005

Received 21 February 2006; revised 22 March 2006; accepted 24 October 2006

Ultrasonic velocities (U), densities (ρ), and coefficient of viscosities (η) are measured for solutions containing iodine monochloride (ICl) and one of the following ethers in equimolar concentration in the range 0.001-0.01M at 303 K. The diphenyl ether, 4-chloroanisole, anisole and 1,4-dioxane are used as donors and the dichloromethane, chloroform, carbon tetrachloride and n-hexane have been used as solvents. Acoustical parameters such as adiabatic compressibility (β), absorption coefficient (α/f2), internal pressure (πi) and cohesive energy (CE) values are calculated from the measured values of U, ρ and η. The trend in the acoustical parameters establishes the formation of charge transfer complexes between iodine monochloride (acceptor) and ethers (donors). The stability constants (K) are calculated for these complexes. The free energy changes (ΔG) for the formation of these complexes are also calculated from K values. The formation constants with polarizability, dielectric strength and dipole moment of the donor and solvent molecules have been correlated. The free energy of activation (ΔG#) and viscous relaxation time (t) are found to be almost constant for these complexes indicating the formation of similar charge transfer complexes in these systems.

Keywords: Ultrasonic velocity, Formation constants, Donor-acceptor complexes, Iodine monochloride, Ethers

IPC Code: B01J19/10

 

         Indian Journal of Pure & Applied Physics

         Vol. 44, December 2006, pp. 909-916

 

Ultrasonic velocities and refractive indices of binary mixtures of
propylene carbonate + n-alkanols

 

D S Wankhede, N N Wankhede, M K Lande & B R Arbad*

Department of Chemistry, Dr Babasaheb Ambedkar Marathwada University, Aurangabad 431 004

*E-mail address: abr_chem@yahoo.co.in

Received 19 May 2006; revised 18 September 2006; accepted 13 October 2006

The densities, ultrasonic velocities and refractive indices of binary mixtures of propylene carbonate + ethanol, n-propanol and n-butanol at 298.15, 303.15 and 308.15 K have been measured over the whole mole fraction range. Experimental data have been used to estimate the isentropic compressibility (Ks), intermolecular free length (Lf), specific acoustic impedance (Z), polarizability (a) and their deviations excess isentropic compressibility (KsE), excess intermolecular free length (LfE), excess acoustic impedance (ZE) and excess refractive index (DnD). The results have been fitted to Redlich-Kister equation and discussed in terms of molecular interactions.

Keywords:   Ultrasonic velocities, Refractive indices, Binary mixtures, Specific acoustic impedance, Polarizability

IPC Code:    G10K11/00

 

       Indian Journal of Pure & Applied Physics

       Vol. 44, December 2006, pp. 917-926

 

Generation of kinetic Alfven wave by velocity shear in the plasma
sheet boundary layer during substorm

 

B V Tiwari, Ruchi Mishra, P Varma & M S Tiwari*

Department of Physics & Electronics, Dr H S Gour University, Sagar, (M P) 470 003

*E-mail: tiwarims@rediffmail.com

Received 24 April 2006; revised 24 August 2006; accepted 12 October 2006

The kinetic Alfven wave (KAW) driven by velocity shear in the plasma sheet boundary layer (PSBL) has been investigated. Expressions for the dispersion relation and growth rate of the kinetic Alfven wave have been derived for the two regimes separately i.e., for the case of weak shear and strong shear. It is found that for both weak and strong shear regimes the resonant electrons act as the main energy source whereas; the ion longitudinal motion suppresses the instability in case of the strong shear. The results explain the generation of energetic KAWs in the PSBL during the substorm onset by the weak velocity shear. As the shear becomes strong during the substorm the energy of the KAWs is transferred to the plasma particles through the Landau damping of the wave, which may then lead to the parallel energisation of the electrons observed recently by Polar satellite. The loss of the Poynting flux, as observed by Polar and Akebono satellite, is also explained in terms of the Landau damping of the KAW by the strong shear of substorm. The temperature anisotropy and density of the plasma particles enhance the growth rate of shear driven KAW at the onset of the substorm.

Keywords: Kinetic Alfven wave, Plasma sheet boundary layer, Substorm event, Weak and strong velocity shear, Landau damping, Loss of poynting flux

IPC Code: H05H

Indian Journal of Pure & Applied Physics

Vol. 44, December 2006, pp. 927-929

Reflectivity of low energy photons from one- and two-dimensional rare hot quantum and classical plasmas

 

S P Tewari* & Jyoti Sood#

*Department of Physics & Astrophysics, University of Delhi, Delhi 110 007

#Department of Physics, Panjab Univeristy, Chandigarh 160 014

*E-mail: sptewari@physics.du.ac.in

Received 20 June 2006; accepted 12 October 2006

The reflectivity of low energy photons from wave vector dependent plasma modes present in one- and two-dimensional rare hot quantum and classical one component plasmas has been computed. The computations have been made for different densities — linear in 1D and areal in 2D at various temperatures to bring out the difference between quantum and classical plasmas. It turns out that the effect of Landau damping is quite significant amongst other results.

Keywords: Quantum wells, Dielectric response, Photon interaction, Optical properties

IPC Code: H05H

Indian Journal of Pure & Applied Physics

Vol. 44, December 2006, pp. 930-934

 

Cation distribution in mixed Mg-Mn ferrite systems from X-ray diffraction technique and saturation magnetization

Gagan Kumar, Meenakshi Kanthwal, B S Chauhan & M Singh*

Department of Physics, Himachal Pradesh University, Summer-Hill, Shimla-171 005,

Received 28 November 2005; revised 16 March 2006; accepted 12 October 2006

Ferrites with general formula Mg0.9 Mn0.1 Fe2-x Inx O4, Mg0.9 Mn0.1 Fe2-y Aly O4 and Mg0.9 Mn0.1 Al0.3 Coz Fe1.7-z4 (where x, y = 0.0, 0.1, 0.3, 0.5 and z=0.3, 0.5, 0.7) were prepared by citrate precursor technique and studied by means of X-ray diffraction and saturation magnetization. The X-ray analysis confirmed the single-phase formation of the sample. The cation distribution is inferred from the results of X-ray diffraction and magnetization measurements.

Keywords: Ferrites, Cation distribution, Saturation magnetization, Magneton number

IPC Code: H0SH

Indian Journal of Pure & Applied Physics

Vol. 44, December 2006, pp. 935-938

 

Compensation effect of ac conduction in Se80Te20 and Se80Te10M10
(M = Cd, In, Sb) chalcogenide glasses

N Mehtaa, D Kumarb & A Kumarc

aDepartment of Physics, Pranveer Singh Institute of Technology, Kanpur

bDepartment of Physics, JSS Academy of Technical Education, Noida

cDepartment of Physics, Harcourt Butler Technological Institute, Kanpur

Received 4 April 2006; revised 31 August 2006; accepted 4 October 2006

In many amorphous and liquid semiconductors and other class of materials, Meyer-Neldel rule is observed in the dc conductivity, where the pre-exponential factor (s0) is found to increase exponentially with the activation energy (DE). In the present paper, the observation of Meyer- Neldel rule in case of ac conductivity near the room temperature in bulk samples of Se80Te20 and Se80Te10M10 (M = Cd, In, Sb) chalcogenide glasses has been reported.

Keywords: ac Conductivity, Chalcogenide glasses, Pre-exponential factor, Meyer-Neldel rule

IPC Code: G01R

 

Indian Journal of Pure & Applied Physics

Vol. 44, December 2006, pp. 939-942

 

Molecular associations in binary mixture of pyridine and N, N-dimethylacetamide in benzene solution using microwave absorption data

Sandeep Kumar, D R Sharma, N Thakur, N S Negi & V S Rangra

Department of Physics, Himachal Pradesh University, Shimla 171 005

E-mail- sndp_bhardwaj@yahoo.com, sndpbhardwaj@gmail.com

Received 25 July 2005; revised 10 October 2006; accepted 13 October 2006

The dielectric relaxation time () of binary mixtures of different molar concentrations of pyridine (C5H5N) and N, N- dimethylacetamide (DMA) in benzene solution has been calculated by using standard microwave techniques and Gopala Krishna's [Trans Farad Soc, 33 (1957) 767.] single frequency (9.875 GHz) concentration variational method at different temperatures (25, 30, 35 and 40°C). It is found that the dielectric relaxation time () varies non-linearly with the increasing molar concentration of pyridine in the binary mixture of pyridine and DMA. Hence, solute-solvent and solute-solute molecular associations have been proposed.

Keywords: Dielectric relaxation, Binary mixture, Pyridine, N, N-dimethylacetamide

IPC Code: G0lR 27/26

Indian Journal of Pure & Applied Physics

Vol. 44, December 2006, pp. 943-952

Study of dielectric relaxation and dipole moment of some hydrogen bonded solvent binary mixtures in 1,4-dioxane

R J Sengwa*, Madhvi, Abhilasha & Sonu Sankhla

Dielectric Research Laboratory, Department of Physics, J N V University, Jodhpur 342 005

E-mail: rjsengwa@rediffmail.com

Received 9 March 2005; revised 6 September 2006; accepted 12 October 2006

The dielectric relaxation and dipole moment of different concentration binary mixtures of mono methyl, mono ethyl and mono butyl ethers of ethylene glycol with four polar solvents i.e. ethyl alcohol, glycerol, dimethyl sulphoxide and dimethyl formamide have been measured in dilute solutions of 1,4-dioxane at 35°C. The measured values of permittivity (e¢) and dielectric loss (e²) at 10.1 GHz, static dielectric constant (eo) at 1 MHz and high frequency limiting dielectric constant (e¥) have been used to determine the values of molecular relaxation time (to), and dipole moment (m) of the different composition binary mixtures. The analysis of the results based on hetero-association in these binary systems, indicates the existence of different characteristic heterogeneous species in dilute solutions. The comparative values of to and m of the various binary mixtures of different composition also suggest that the nature of heterogeneous interaction varies with the type of polar solvent and also constituents composition in the binary mixture.

Keywords: Dielectric relaxation, Dipole moment, Binary mixtures, Polar solvents, Heterogeneous interactions, Molecular dynamics

IPC Code: G01R31/12

 

Indian Journal of Pure & Applied Physics

Vol. 44, December 2006, pp. 953-958

 

 

Temperature, current and doping dependence of non-ideality factor for pnp and npn punch-through structures

Khurshed Ahmad Shah & S S Islam

Department of Applied Sciences and Humanities, Faculty of Engineering and

Technology, Jamia Millia Islamia (Central University), New Delhi 110 025

*E-mail: Shahkhurshaid@yahoo.co.in

Received 16 January 2006; revised 11 September 2006; accepted 13 October 2006

The effect of punch-through in devices is of great importance in electronic industry. In this paper, an efficient, unconditionally stable, simple and accurate method has been presented for solving non-linear transport equations for carriers with appropriate choice of initial values of dependent variables. The methods are so fast that parameter dependence of non-ideality for punch-through structures has been incorporated easily and their specific effects have been determined precisely. The present study reveals that the non-ideality factor decreases with temperature and increases with current and doping concentration of the active region of the device. The relative changes are larger at lower temperatures and more effective at higher impurity density of the active region of the device. This study enables to have better understanding of the punch-through mechanism and design of these devices.

Keywords: Punch-through diode, Numerical method, Parametric study, Non-ideality factor

IPC Code: H01L29/861