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ISSN: 00195596 
CODEN: IJOPAU 43 (4) 233  314 

Volume 43 
Number 4 
April 2005 
CONTENTS
Atomic and Molecular Physics 

Spectroscopic studies of molecules observed in comets R R Reddy*, K Rama Gopal, Y Nazeer Ahammed, D Baba Basha,K Narasimhulu & L Siva Sankar Reddy 
237 
Spectral lines of some volatile hydride forming elements for determination of excitation temperature in analytical plasmas 
246 
Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics and Fluid Dynamics 

Alloptical system for wide range decimal multiplexing 
253 
Ultrasonic studies on dilute solutions of water in nalcohols and 2alkoxyethanols 
259 
Condensed Matter: Structural, Mechanical and Thermal Properties 

Extending Wertheim’s perturbation theory to aperiodic solids 
265 
Absolute thermoelectric power in heavily doped ntype silicon 
270 
Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties 

Magnetic order and electrical resistance in manganites 
273 
Study of Pr_{x}Y_{1x}Ba_{2}Cu_{3}O_{7d }high T_{c} superconductors 
279 
Dielectric study of surface modification of linear low density polyethylene treated with chromic acid and sodium carbonate 
287 
Effect of processing and polarizer on the electrical properties of MnZn ferrites 
291 
Study of N M R spin lattice relaxation of several aldehydes 
295 
Interdisciplinary Physics and Related Areas of Science and Technology 

Novel power VDMOSFET structure with vertical floating islands and trench gate 
301 
Point contact one injection current in solid insulators with traps 
308 
________
*The corresponding author has been indicated by (*) mark in case of papers with more than one author.
Indian Journal of Pure & Applied Physics
Vol. 43, April 2005, pp. 237245
R R Reddy, K Rama Gopal, Y Nazeer Ahammed, D Baba Basha, K Narasimhulu & L Siva Sankar Reddy
The potential energy curves for the different electronic states of molecules like N_{2}^{+}, N_{2}, OH and S_{2 }observed in comets are constructed by using the Rydberg–Klein–Rees method as modified by Vanderslice et al. The ground state dissociation energies are determined by curve fitting technique using the five parameter HulburtHirschfelder (HH) function. The estimated dissociation energies are 8.587±0.248, 9.620±0.275, 4.308±0.118 and 4.325 ±0.115 eV for N_{2}^{+}, N_{2}, OH and S_{2 }respectively. These values are in good agreement with the literature values. The rcentroids and FranckCondon factors (FC factors) for the band system of A–X system of N_{2}^{+} and A–X and B–X system of N_{2} molecules have been calculated employing approximate analytical methods of Jarmain and Fraser and Nicholls and Jarmain. The absence of the bands in these systems is explained.
Keywords: Comets, FranckCondon factors, rcentroids, Astronomical spectra, Potential energy curves
IPC Code: G01J3/28
Indian Journal of Pure & Applied Physics
Vol. 43, April 2005, pp 246252
M A Eid, H R Moustafa, E A AlAshkar & S S Ali
The spectra of some volatile hydride forming elements have been investigated to select thermometric species for determination of excitation temperature in analytical plasmas working in argon under atmospheric pressure. Groups of lines of As I, Sb I and Sn I in addition to Ar I were found appropriate for the determination of excitation temperature in inductively coupled plasma (ICP) and wallstabilized arc (WSA). The Boltzmann plots were straight lines, which determined temperature in ICP and WSA using different groups of spectral lines that agree well with each other as well with the most familiarly used thermometric species. These lines are recommended for determination of temperature when gaseous hydrides are introduced into the plasma and no other thermometric species except the atoms of working gas are present.
Keywords: Excitation temperature, Inductively coupled plasma, Wallstabilized arc, Volatile hydride forming elements
IPC Code: H03L7/26
Indian Journal of Pure & Applied Physics
Vol. 43, April 2005, pp. 253258
Archan Kumar Das & Sourangshu Mukhopadhyay
In alloptical parallel information processing, data computation and in optical communication, multiplexing and demultiplexing have a very strong role. Many multiplexing schemes in digital optical processing are already proposed. A new type of alloptical digital multiplexing system with only two triggering channels has been reported. Any input channel can be multiplexed here out of any number of such input channels with only those two triggering channels.
Keywords: Optical computation, Spatial input encoding, Parallel processing, Logic operations, Multiplexing
IPC Code: G02F3/00
Indian Journal of Pure & Applied Physics
Vol. 43, April 2005, pp. 259264
G Venkata Ramana and E Rajagopal & N Manohara Murthy
Ultrasonic
velocities in dilute solutions of water in nalcohols (methanol, ethanol,
npropanol and nbutanol), and
2alkoxyethanols (2methoxyethanol, 2ethoxyethanol and 2butoxyethanol) have
been determined at 298.15 K using single crystal variable path interferometer
working at 3 MHz. The excess ultrasonic velocities have been evaluated using the
formula, which is thermodynamically valid. A distinctive nonlinear variation of
ultrasonic velocity with concentration of water in both nalcohols and
2alkoxyethanols has been observed over a small range of concentration. A
similar behaviour is also observed in the concentration dependence of excess
ultrasonic velocity in these solutions. This behaviour has been explained by
considering the existence of water molecules as monomers up to certain optimum
concentration, (X_{2})_{opt}, of water and the nonlinear
behaviour observed beyond (X_{2})_{opt} has been
explained in the light of waterwater and wateralcohol interactions leading to
the formation of islands of wateralcohol extended structures.
Keywords: Ultrasonic study, Water, nalcohols, 2alkoxyethanols
IPC Code: B01J19/10
Indian Journal of Pure & Applied Physics
Vol. 43, April 2005, pp. 265269
Pavan Kumar Verma, D K Dwivedi & K N Khanna
A theoretical study of twodimensional hard homonuclear dumbbellshaped aperiodic molecular system with a high anisotropy parameter d* = 0.924 employing Wertheim’s firstorder perturbation theory has been reported. The thermodynamic state of the aperiodic molecular solid known as DCcrystalline phase has been presented. The equation of state of twodimensional dumbbell shaped molecules in fluid, HB and DC crystalline phases has been compared.
Keywords : Wertheim’s Perturbation theory, Aperiodic Solids, Anisotropy parameter
IPC Code: G01K
Indian Journal of Pure & Applied Physics
Vol. 43, April 2005, pp. 270272
Bantikassegn Workalemahu
The absolute thermoelectric power in a heavily doped ntype silicon by taking into account the effect of band tails has been calculated. The calculations show that the effect of incorporating the band tails results in increasing the value of absolute thermoelectric power.
Keywords: Thermoelectric power, ntype, Silicon, Band tails
IPC Code: H01L
Indian Journal of Pure & Applied Physics
Vol. 43, April 2005, pp. 273278
R J Singh & P K Sharma
The electrical resistance versus temperature behaviour of the manganites La_{1}_{x}Ba_{x}MnO_{3} (x=0.3,0.4,0.5); La_{1}_{x}Pb_{x}MnO_{3 }(x = 0.2,0.3,0.33) and La_{1}_{x}Sr_{x}MnO_{3} (x = 0.1,0.2,0.4) has been investigated. The temperatures at which the substances have maximum resistance have been found to be much lower than their Curie temperatures. The variation of resistance with temperature is not smooth, but the graphs show different slopes. The electron paramagnetic resonance of these substances shows a new signal in the spectra on a little increase of microwave field from the usual values. It has been interpreted as phase separations in the materials with Mn^{3+} and Mn^{4+} spins aligned in opposite directions. Based on this idea, magnetic order and electrical resistance of the materials are shown to be directly correlated.
Keywords: Manganites, Electron paramagnetic resonance, Phase separations
IPC Code : G01R27/02; H01F1/00
Indian Journal of Pure & Applied Physics
Vol. 43, April 2005, pp 279286
B N Dole & S S Shah
The
substitution of Pr in high T_{c} superconducting compound plays
very interesting role such as annihilation of superconductivity with increase of
Pr concentration, which is not adequately explained yet. The samples of the
system
Y_{1x}Pr_{x}Ba_{2}Cu_{3}O_{7d}
with compositions (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared by
well known conventional ceramic route and chemical route. The results of
resistivity, Xray diffraction, orthorhombicity, Xray density, bulk density,
volume cell and oxygen content of both the routes are reported. The samples
prepared by chemical route give better results than conventional ceramic route.
Bond distances obtained from neutron diffraction show that the electron phonon
interaction becomes weaker and results in loss of superconductivity.
Keywords: Superconductor, Xray diffraction, Orthorhombicity, Neutron diffraction, Electronphonon interaction
IPC Code: H01L39/00
Indian Journal of Pure & Applied Physics
Vol. 43, April 2005, pp. 287290
S K Dash, K C Mishra, S N Mishra & B B Swain
Received 12 February 2004; revised 3 November 2004; accepted 25 January 2005
The relative permittivity (e˘) and dielectric loss (e˘˘) of linear low density polyethylene (LLDPE) sample of 60 μm thickness treated successively with a highly oxidizing environment like chromic acid of normality N/5 to N/30 for time duration of 0.5 to 12 hr and sodium carbonate for 24 hr are measured using GRA 650A impedance bridge over 100 Hz to 10 kHz range at 303.16±1K. The N/10 chromic acid treated sample exhibited increase in values of e˘ (from 3.2 to 4.3) and e˘˘ (from 0.48 to 0.75) relative to the virgin sample at 300 Hz while the rest of the samples recorded reduction. But these chromic acid treated LLDPE samples being further treated with N/10 sodium carbonate (Na_{2}CO_{3}), exhibit change in e˘ and e˘˘ values in as much as those for N/10 chromic acid treated sample drops while that of N/15 chromic acid treated sample increases significantly. This indicates intense polarization penetrating to reasonable depth of the surface of the material. The higher value of e˘ and e˘˘ in N/10 chromic acid treated sample may be due to intramolecular threedimensional network of Hbonding between PECOOH species. Attempt is made to explain these features.
Keywords: Relative permittivity, Dielectric loss, Linear low density polyethylene, Polymers
IPC Code: G01R31/12
Indian Journal of Pure & Applied Physics
Vol. 43, April 2005, pp. 291294
Madan Lal, D K Sharma & M Singh
The effect of processing technique as well as the effect of oxidizing agent on the electrical properties of Mn_{0.47}Zn_{0.53}Fe_{2}O_{4} ferrite has been presented. The dc resistivity is improved by citrate precursor method as compared to normal ceramic method and it is further improved by the addition of H_{2}O_{2 }(hydrogen peroxide), which acts as a strong oxidizing agent. The decrease in dielectric constant and dielectric loss factor by addition of oxidizing agent is justified by inverse proportionality between resistivity and dielectric constant.
Keywords: MnZn, Ferrites, Oxidizing agent, Electrical properties
IPC Code: G01R27/26, B23H1/00
Indian Journal of Pure & Applied Physics
Vol. 43, April 2005, pp 295300
S K Vaish, Anupam Singh, A K Singh & N K Mehrotra
The NMR spin lattice relaxation of various aldehydes has been investigated. The experimental values of NMR spin lattice relaxation time T1 of benzaldehyde, anisaldehyde, ocholorobenzaldehyde and phydroxybenzaldehyde have been correlated with the calculated value of N M R spin lattice relaxation time T1 obtained using various equations for dielectric relaxation time t. It has been concluded that Writz equation and Murty equation are better substitute for the correlation time in calculating NMR spin lattice relaxation time than Debye equation as used by BPP (Bloembergen, Purcell and Pound).
Keywords: NMR spin lattice relaxation, Aldehydes
IPC Code: G01R33/20
Indian Journal of Pure & Applied Physics
Vol. 43, April 2005, pp. 301307
Rakesh Vaid & Naresh Padha
A novel power VDMOSFET (vertical doublediffused MOSFET) structure, simulated using PISCESII, a 2dimensional numerical device simulator has been described. The proposed device structure is based on the floating islands (FLI)diode concept and trench gate technology. Extensive simulations were performed to understand physics of the device through various internal electrical quantities like potential distribution, electric field, etc. in different regions of the device both in on/off states.The simulation results show that the new device has a low onresistance by virtue of reduced electric field in its drift region as well as due to the removal of parasitic JFET region resistance. Trench gate acts as a field plate to avoid the punchthrough thus enhancing the breakdown voltage. For a 100 Volts design, an approximate 15% increase in the breakdown voltage has been observed in the proposed device compared to the conventional FLIMOSFET without trench gate.
Keywords: Power MOSFET, VDMOSFET, FLIMOSFET, Device simulation
IPC Code: H01J 1/00
Indian Journal of Pure & Applied Physics
Vol. 43, April 2005, pp. 308310
N K Sharma & P M Anbarasan٭
One injection current in insulator has been studied widely for a long time in various geometries. An important field for study is the analytical treatment of current carriers in deep trap region well below the fermi level. In the present problem, a cylindrical structure has been taken into consideration. The effects of traps are included in the analysis. The problem becomes complicated in the presence of traps and thermal free carriers because there are various transitions regimes present in the complete currentvoltage characteristics.
Keywords: Point contact, Injection current, Traps, Insulators
IPC Code: H01B