Indian Journal of Pure and Applied Physics

      Total visitors: 1,527  since 19-09-06

 ISSN: 0019-5596

CODEN: IJOPAU 44 (9) 633- 712

VOLUME  44

NUMBER 9

SEPTEMBER 2006

CONTENTS

Review Article

 

EPR probes ion dynamics of superionic conductors

637

C S Sunandana* & D Bharathi Mohan

 

Atomic and Molecular Physics

 

Study of vibrational spectra of 4-methyl-3-nitrobenzaldehyde

644

B S Yadav*, S K Tyagi & Seema

 

Study of 136Xe ion induced effects in Makrofol-KL polycarbonate by positron annihilation

649

Rajesh Kumar* & Rajendra Prasad

 

Vibrational spectra and thermodynamics of biomolecule : 5-chlorocytosine

653

V K Rastogi*, M A Palafox, Kamil Lang, S K Singhal, R K Soni & Rekha Sharma

 

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

 

Development of an experimental arrangement for precise measurement of angular distribution of ultrasound scattering

661

Ratan K Saha*, Manas K Roy, Subhajit Karamkar, Saibal Saha & Swapan K Sen

 

Ultrasonic study of ion-solvent interactions in aqueous and non-aqueous solution of transition and inner transition metal ions

670

V Kannappan* & S Chidambara Vinayagam

 

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

 

Role of inter-site hybrid interactions in itinerant ferromagnetism

677

Piyush Dua, Sunil Panwar & Ishwar Singh*

 

Study of ion electron beam irradiation effects in Al-Sb bilayer thin films

685

R K Mangal, M Singh, Y K Vijay* & D K Avasthi

 

Optical, structural and electrical properties of zinc sulphide vacuum evaporated thin film

690

Pawan Kumar*, Aravind Kumar, P N Dixit & T P Sharma

 

Opto-electronic humidity sensor with incident light in the form of a conical beam

694

B C Yadav*, Anchal Srivastava, R K Shukla & G C Dubey

 

Low-macroscopic field emission from carbon fibers synthesized by direct current plasma enhanced chemical vapour deposition

700

S F Ahmed, S Das, M K Mitra & K K Chattopadhyay*

 

Structure and properties of vacuum deposited cadmium telluride thin films

705

K N Shreekanthan, Kasturi V Bangera, G K Shivakumar* & M G Mahesha

 

 

___________

*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, September 2006, pp. 637-643

 

 

EPR probes ion dynamics of superionic conductors

 

C S Sunandana* & D Bharathi Mohan

School of Physics, University of Hyderabad, Hyderabad 500 046

*E-mail:csssp@uohyd.ernet.in

Received 6 December 2005; accepted 10 July 2006

Superionic conductors possess large concentrations of monovalent mobile ions such as Ag+ in AgI and Li+ in LiClO4:PEG that travel through diffusion even larger number of defect sites leading to ionic conductivities of the order of 1S/cm around ambient temperature often through structural phase transitions. Any mobile ion complex that is part of a network or unit cell becoming paramagnetic through electron/hole capture, can serve as a probe for ion dynamics and phase transitions. This paper identifies the basic issues of superionic conductors from EPR standpoint and demonstrates through five case studies the power of the technique to investigate conduction mechanisms in terms of changes in structure and dynamics around the probe.

Keywords: Superionic conductors, Electron paramagnetic resonance, Structural phase transitions

IPC Code: G01N25/18

 

Indian Journal of Pure & Applied Physics

Vol. 44, September 2006, pp. 644-648

 

Study of vibrational spectra of 4-methyl-3-nitrobenzaldehyde

B S Yadav, S K Tyagi* & Seema**

Molecular Spectroscopy and Biophysics Laboratory, D N (PG) College, Meerut 250 002

 *Department. of Physics, C S S S (P G ) College, Machhra (Meerut) U P

 **Department. of Chemistry, J V College, Baraut, U P

 *E-mail: sktyagi12@rediffmail.com

Received 13 September 2005; revised 22 December 2005; accepted 6 July 2006

The vibrational (infrared and Raman) spectra of 4-methyl-3-nitrobenzaldehyde have been reported. The assignments of fundamentals are proposed and discussed by assuming the molecule under CS point group symmetry.

Keywords: Infrared and Raman specroscopy, vibrational frequencies, methyl nitro benzaldehyde

IPC Code: G01J3/28

Indian Journal of Pure & Applied Physics

Vol. 44, September 2006, pp. 649-652

 

Study of 136Xe ion induced effects in Makrofol-KL polycarbonate by

positron annihilation

 

Rajesh Kumar* & Rajendra Prasad

Department of Applied Physics, Z H College of Engineering & Technology, Aligarh Muslim University, Aligarh 202 002

*E-mail: drrajesh04@rediffmail.com

Received 14 June 2005; revised 2 May 2006; accepted 4 July 2006

Polymer films are finding many applications like in ion track registration, microfilters for gas separation, water purification etc. Positron Annihilation Lifetime Spectroscopy (PALS) provides non-destructive and non-interfering probe, having high detection efficiency for free volume hole properties. Makrofol - KL polycarbonate films (22 µm) were irradiated by 136Xe (11.56 MeV/n) with the fluences of 105 ions/cm2. Ion beam modifications were studied by PALS technique. From the o-Ps lifetime, mean free volume, hole radius and microvoid volume have been obtained which are found to increase with irradiation.

Keywords: Makrofol-KL polycarbonate, 136Xe ion irradiation, Positron lifetime, Free volume, Ion beam modification

IPC Code: G01J2/12

Indian Journal of Pure & Applied Physics

Vol. 44, September 2006, pp. 653-660

 

Vibrational spectra and thermodynamics of biomolecule: 5-chlorocytosine

 

V K Rastogi1, M A Palafox2, Kamil Lang3, S K Singhal1, R K Soni4 & Rekha Sharma5

1Department of Physics, CCS University, Meerut 250 004

2Departamento de Quimica-Fisica I, Facultad de Ciencias Quimicas, Universidad Complutense, Madrid-28040, Spain

3Department of Kinetics, Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic, Czech Republic

4Department of Chemistry, CCS University, Meerut 250 004

5Department of Physics, Meerut College, Meerut 250 004

Received 11 November 2005; revised 9 May 2006; accepted 12 June 2006

The laser Raman and IR spectra of biomolecule 5-chlorocytosine have been recorded in solid phase. The vibrational spectra have been analysed assuming planar geometry and Cs point group symmetry for the molecule and observed fundamentals have been assigned to different normal modes of vibrations. The studies indicate that the features that are characteristic of the vibrational spectra of cytosine and its derivatives are retained by the spectrum of 5-chlorocytosine and it exists in amino-oxo form in solid phase. The validity of empirical relation ns = 345.5 + 0.876 nasym suggests the equivalence of the two NH bonds of the NH2 group. The observed fundamental frequencies are used to calculate the thermodynamic functions, namely, the enthalpy, entropy, heat capacity and the free energy were also computed in the temperature range 200-1000K using the rigid-rotor harmonic oscillator approximation. For this purpose, the fundamental wavenumbers obtained in the present study were taken, while the structural parameters were taken from literature.

Keywords: Vibrational spectra, 5-chlorocytosine, Laser Raman spectra

IPC Code: G01J3/28

Indian Journal of Pure & Applied Physics

Vol. 44, September 2006, pp. 661-669

 

Development of an experimental arrangement for precise measurement of
angular distribution of ultrasound scattering

 

Ratan K Saha, Manas K Roy* ,Subhajit Karmakar, Saibal Saha & Swapan K Sen

Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064

*Sateyendra Nath Bose National Centre of Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 064

*E-mail:ratank.saha@saha.ac.in

Received 8 March 2006; revised 4 July 2006; accepted 14 July 2006

This paper describes step-by-step development of a custom-made measurement system and also provides an assessment of the reliability of the set-up. The angular distribution of the scattered field generated by a sufficiently long cylindrical scatterer in water medium has been measured by this system. The measured values have been compared with the theoretical results to validate the instrument. The theoretical curves have been obtained by using the Faran’s theory [J Acoust Society of America, 23(4) (1951) 405]. In this study, an acoustic wave of frequency 2.19 MHz emitted by a medical ultrasound source has been employed to provide energy to the scattering object. Two steel wires of different gauges (0.68mm and 0.91mm in diameter) with size parameters ka ≈ 3.12 and 4.17, respectively, have been taken as prototype scatterers. Here, k is the wave number of the incident wave and a is the radius of the target. Our results show that the system is stable, capable of precise scattering measurements and measured values are reproducible. The system has also the flexibility of incorporating scatters of different shapes and also ultrasound probes of different frequencies.

Keywords: Ultrasound scattering, Pulse-echo imaging, Ultrasound

IPC Code: A61N7/00

Indian Journal of Pure & Applied Physics

Vol. 44, September 2006, pp 670-676

 

Ultrasonic study of ion-solvent interactions in aqueous and non-aqueous
solutions of transition and inner transition metal ions

V Kannappan & S Chidambara Vinayagam

Postgraduate Department of Chemistry, Presidency College, Chennai 600 005

Received 20 February 2006; revised 5 May 2006; accepted 22 May 2006

Ultrasonic velocities(u) and densities(ρ) of aqueous and dimethyl sulphoxide(DMSO) solutions of manganous(II) sulphate cobalt(II) chloride, nickel(II) sulphate, ferrous sulphate, copper(II) sulphate, zinc(II) sulphate, lanthanum(III) nitrate, cerium(IV) nitrate, uranyl nitrate and thorium(IV) nitrate in a wide range of concentrations at a temperature 303K have been measured. Acoustical parameters, such as, adiabatic compressibility (b), free length (Lf) and solvation number(Sn) are computed to assess the ion-solvent interaction in these solutions . It is found that the ion-solvent interactions depend on concentration, ionic size and nature of metal ion. The transition and inner transition metal ions behave as structure breaker for the associated clusters of water molecules, especially in dilute solution, as evidenced from the trend in the solvation number with molarity. It is also found that the strength of ion-dipole interaction in aqueous solution of the metal ion is also dependent on concentration.

Keywords: Ultrasonics, Ion-solvent interactions, Metal ions

IPC Code: B01J19/10

 

Indian Journal of Pure & Applied Physics

Vol. 44, September 2006, pp. 677-684

 

Role of inter-site hybrid interactions in itinerant ferromagnetism

Piyush Dua, Sunil Panwar* & Ishwar Singh

Physics Department, Indian Institute of Technology Roorkee, Roorkee 247 667

*Department of Basic Sciences, College of Engineering and Technology, Gurukul Kangri University, Haridwar 249 404

Received 28 December 2005; accepted 18 July 2006

The role of inter-site hybrid interactions in deciding ferromagnetic state in the itinerant electron (narrow band) systems like some of the transition metals has been studied. We have considered Hubbard like tight binding model alongwith exchange and hybrid interactions. All interactions have been treated within mean-field approximation. It is found that hybrid interactions play significant role at zero as well as finite temperatures in deciding on-set of ferromagnetic state. The variation of effective mass of up and down spin electrons in ferromagnetic state as a function of temperature has been studied. The magnetic susceptibility, optical conductivity and magnetoresistance as a function of temperature have also been studied.

Keywords: Hybrid interactions, Itinerant ferromagnetism, Transition metals, Ferromagnetic state, Optical conductivity, Magnetoresistance, Hubbard Hamiltonian

IPC Code: G01R, H01F

 

Indian Journal of Pure & Applied Physics

Vol. 44, September 2006, pp. 685-689

Study of ion and electron beam irradiation effects in Al-Sb bilayer thin films

 

R K Mangal1,2, M Singh2, Y K Vijay2 & D K Avasthi3

1Jaipur Engineering College & Research Center, Jaipur

2Department of Physics, University of Rajasthan, Jaipur

3Inter University Accelerator Centre, New Delhi

Received 23 January 2006; revised 22 May 2006; accepted 7 July 2006

Thin films having uniform thicknesses of aluminium over different thicknesses of antimony were prepared by thermal evaporation (resistive heating) method at the pressure 10-5 torr. The samples were irradiated by Ag12+ heavy ions of energy 160 Mev at the fluence 2.2´1013 ions/cm2. The similar set of these films have also been irradiated by electron beam having energy 10 keV for two hours. The optical absorption spectra and Rutherford back scattering analysis have been carried out for these films. X-ray diffraction spectra of virgin as well as ion irradiated sample, show orthorhombic structure of the films. These results show that the inter diffusion of bilayer with irradiation effects. It is also suggested that ion beam irradiation gives
the better results in comparison to electron beam. These results confirm the mixing of Al/Sb bilayer by irradiation process.

Keywords: Thin films, Al-Sb, Ion irradiation, Electron irradiation, Absorption, RBS, Optical band gap

IPC Code: H01L29/76

 

Indian Journal of Pure & Applied Physics

Vol. 44, September 2006, pp. 690-693

 

 

Optical, structural and electrical properties of zinc sulphide vacuum evaporated thin film

Pawan Kumar1, Aravind Kumar1, P N Dixit2 & T P Sharma3

1Department of Physics S C R I E T, C C S University, Meerut 250 004

2National Physical Laboratory, Dr K S Krishnan Marg, New Delhi 110 012

3Department of Physics, University of Rajasthan, Jaipur 302 004

Received 11 July 2005; revised 16 January 2006; accepted 8 May 2006

The II-VI group semiconductors are of great importance due to their applications in various opto-electronic devices. Among these semiconductors, zinc sulphide film is the most suitable for its utility in opto-electronic devices. ZnS film has been prepared on glass substrates by using vacuum evaporation method. The optical properties, especially refractive index by transmission spectra of these films have been studied in the wavelength range 400-850 nm using Manifaciers envelope method. The ZnS film has a direct band gap of 3.50 eV. The wurtzite structure of ZnS film has been confirmed by X-ray diffraction analysis. The electrical properties of ZnS especially dark conductivity and photoconductivity at different temperatures have also been studied.

Keywords: Zinc sulphide, Vacuum evaporated thin film, Refractive index, Conductivity

IPC Code: H01L 27/00

Indian Journal of Pure & Applied Physics

Vol. 44, September 2006, pp. 694-699

 

Opto-electronic humidity sensor with incident light in the form of a conical beam

B C Yadav, Anchal Srivastava, R K Shukla & G C Dubey*

Opto-Electronic Research Laboratory, Department of Physics, University of Lucknow, Lucknow 226 007

*Solid State Physics Laboratory, Lucknow Road, Delhi 110 007

E-mail: balchandra_yadav@rediffmail.com

Received 10 November 2005; revised 5 May 2006; accepted 5 July 2006

In the present work, an extensive experimental investigation of TiO2 film has been carried out. TiO2 films have been deposited on a prism base by using sol-gel spin process. As the humidity increases in the environment where such films are placed, physisorption and chemisorption of water take place through the pores of films. This leads to a corresponding modulation in the intensity of reflected light. Thus, relative humidity is estimated directly in terms of modulation in the intensity of light observed on a digital power meter. Surface morphology of TiO2 films has also been studied.

Keywords: Humidity Sensor, Thin Film, Conical beam

IPC Code:G02B

Indian Journal of Pure & Applied Physics

Vol. 44, September 2006, pp. 700-704

 

 

Low-macroscopic field emission from carbon fibers synthesized by direct current plasma enhanced chemical vapour deposition

Sk F Ahmeda, S Dasa, M K Mitrab & K K Chattopadhyaya,b

aThin Film & Nanoscience Laboratory, Department of Physics

bNanoscience and Technology Center, Jadavpur University, Kolkata 700 032

Received 10 April 2006; revised 3 July 2006; accepted 17 July 2006

Carbon fibers, in thin film form, have been synthesized on Si substrates via direct current plasma enhanced chemical vapour deposition with acetylene as a precursor using Ni as a catalyst at substrate temperature 750-850°C. X-ray diffraction studies confirmed the graphitic phase of the carbon fibers. Surface morphologies of the films have been studied by a scanning electron microscope and an atomic force microscope. The graphitic carbon fibers have showed good field emission properties with a turn-on field lying in the range 2.57-9.71 V/mm for films deposited with different substrate temperatures. The field enhancement factor and the approximate work function have also been calculated. The emission properties have been studied for different anode-sample spacing for the carbon fibers film deposited at 850°C.

Keywords: Carbon fibers, Thin film, Field emission, Plasma

IPC Code: C03C

Indian Journal of Pure & Applied Physics

Vol. 44, September 2006, pp 705-708

 

Structure and properties of vacuum deposited cadmium telluride thin films

K N Shreekanthan*, Kasturi V Bangera, G K Shivakumar+ & M G Mahesha

Department of Physics, National Institute of Technology, Surathkal, Srinivasnagar 575 025 Karnataka

*Department of Physics, N S S College, Manjeri 676 122, Kerala

Received 13 February 2006; revised 16 May 2006 ; accepted 6 June 2006

Systematic and detailed study of the growth and properties of vacuum deposited cadmium telluride thin films was made. Both p- and n-type films were grown and these films were characterized for their structural, optical, and electrical properties. The crystallographic structure of the deposits was found to be dependent on the rate of deposition. Low deposition rates were observed to result in hexagonal deposits whereas high rates of deposition favoured cubic structure for the film. Electrical and optical properties were also found to be dependent on the deposition parameters.

Keywords: Thin films, Cadmium telluride thin films, Cubic structure

IPC Code: H01L