022556   Kailash ;Raju K M;Shrivastava S K (Dep of Phys, Brahmanand P G Coll, Rath, Hamirpur-210 431, Email: krishnamurtiraju@yahoo.com) : Acoustical investigation of magnesium oxide. Indian J pure appl Phys 2006, 44(3), 230-4.

The higher order elastic constants of MgO starting from basic parameters viz. the nearest neighbour distance, hardness parameter using Coulomb and Born-Mayer potentials have been obtained. These values are utilized to obtain Gruneisen parameters and non-linearity constants. Non-linearity constants ratio, ultrasonic attenuation due to phonon-phonon interaction (α/f²)_p-p and thermo elastic loss (∝/f²)_th are calculated in a wide temperature range along <100>, <110> and <111> crystallographic directions of propagation for longitudinal and shear waves and compared with available theoretical and experimental results.

6 illus, 2 tables, 26 ref

022555   Joshipura K N;Vaishnav B G;Limbachiya C G (Dep of Phys, Sardar Patel Univ, Vallabh Vidyanagar-388 120, Email: knjoshipura@yahoo.com) : Ionization and excitation of some atomic targets and metal oxides by electron impact. Pramana J Phys 2006, 66(2), 403-14.

Calculates total inelastic and total ionization cross-sections for collisions of electrons on atomic targets oxygen (O), aluminium (Al) and copper (Cu) and metal oxides A1O and Al?2O, at impact energies from near excitation threshold to 2000 eV. A complex (optical) energy-dependent interaction potential is used to derive total inelastic cross-sections resulting from ionization as well as excitation processes. The inelastic cross-sections are bifurcated into discrete and continuum contributions and total ionization cross-sections have been deduced therefrom. The calculation also provides information, hitherto sparse, on the excitation processes in the atomic targets 0, Al, Cu and metal oxides AlO, Al₂O. Adequate comparisons are made with other theoretical and experimental data.

5 illus, 2 tables, 20 ref

022554   Joshi M;Gupta B R K (Dep of Phys, G B Pant Univ of Agric and Technol, Pantnagar-263 145 Juttaranchal, India, Email: brkg@rediffmail.com) : Temperature dependence of adiabatic elastic moduli of (Mg_1-x, Fe_x)₂SiO₄. Indian J Phys 2006, 80(1), 85-7.

Investigate the temperature dependence of the bulk modulus and shear modulus of olivine minerals with different compositions. The calculations are performed with the help of high pressure-high temperature equation of state based on thermodynamic analysis. The anharmonic term arising due to thermal expansion, has been taken into account in the expansion of logarithmic series of the thermodynamic data. The results obtained for two olivines viz. (Mg_1-x, Fe_x)₂ SiO₄ with x = 0.08 and x = 0.10 are discussed and compared with the experimental data. The excellent agreement with the experimental data is achieved.

4 illus, 16 ref

022553   Jha P K (Dep of Phys Fac of Sci, MS Univ of Baroda, Vadodara-390 002, Email: prafullaj@yahoo.com) : Low frequency phonons in nanoparticles. Indian J pure appl Phys 2006, 44(2), 87-92.

The consequence of the phonon confinement on the phonon spectra particularly the low frequency spectra in nanocrystal quantum dots has been investigated. Due to the phonon confinement effect, there appears spheroidal and quadrupolar modes of nanoparticles in the low frequency spectra. The frequency of these modes increases with the decrease of the size of the nanocrystal quantum dot (nanoparticle). The effect of surrounding medium on the phonon spectra of the nanoparticles, which is observed as the broadening of the phonon line shape due to the acoustic mismatch at the surface of the nanoparticles has also been discussed. The effect of density of the surrounding medium on the phonon modes has been discussed and the results on the damping constant and quality factor have been studied.

5 illus, 46 ref

022552   Iqbal S S;Biswas M;Siddiqui J Y;guha D (E E Dep, King Fahd Univ of Petrol and Miner, Dhahran, Saudi Arabia, Email: sheikhsi@kfupm.edu.sa) : Performance of cavity backed inverted microstrip broadband antenna. Indian J Radio Space Phys 2006, 35(1), 54-8.

An inverted microstrip circular patch with a parasitic element printed back-to-back on the same substrate and backed by a cylindrical metallic cavity is investigated as a compact integratable broadband antenna. The cavity effect in changing its impedance behaviour is thoroughly examined and an optimized X-band design is presented. As much as 11% bandwidth is apparent from the design data. Principal plane radiation patterns are also examined, showing above 98% efficiency and 10.97 dB directivity.

8 illus, 11 ref

022551   Iheonu E E;Oyekola O S (Bldg Res Dep, Bldg Phys Unit Niger Bldg & Rd Res Inst, km 10, Ota-Idiroko Road, P M B 1055, Ota, Ogun State, Nigeria) : Vertical drift velocity in the daytime F-region at Ibadan estimated from ionosonde data. Indian J Radio Space Phys 2006, 35(1), 9-13.

Electron drifts distributions obtained from ionosonde measurements at Ibadan (lat. 7.4°N, long. 3.9°E; magn lat. 3.0°S), Nigeria, have been used to estimate daytime F-region vertical drift velocities during periods of low and high solar activity. Values of the drift velocity near 300 km altitude at Ibadan are shown to be in good agreement with the results of experiments carried out at other equatorial stations. The proposed method may be relevant to the bottomside ionosphere for estimating vertical drift velocities, especially, at locations close to the magnetic equator where measurements are not carried out on a continuous basis.

3 illus, 1 table, 16 ref

022550   Gupta N;Tyagi B P (Phys Grp, Birla Inst of Technol and Sci, Pilani-Goa Campus, Goa-403 726, Email: navneet_dun@rediffmail.com) : Analytical modelling of carrier transport through transverse and longitudinal grain boundaries in polysilicon thin-film transistors. Indian J Engng Mater Sci 2006, 13(2), 145-8.

Carrier transport through transverse and longitudinal grain boundaries (GBs) in polysilicon thin film transistors (poly-Si TFTs) has been studied. The model considers an array of square grains in the channel of poly-Si TFT in which current flows along the longitudinal GBs and through the grains and the transverse GBs. The variation of field-effect mobility (μ_FE) and drain current (I_D) is computed for different values of grain size. At low gate voltage the longitudinal GBs are seen to influence the field-effect mobility and drain current. As gate voltage increases, the effect of transverse GBs is found to account for experimental results. This is attributed to the fact that at low gate voltage, the carriers moving through longitudinal GBs have more opportunities to be trapped at the trapping sites and as gate voltage increases the carriers have sufficient energy to bypass the longitudinal GBs and obstructed by transverse GBs alone. This may be the reason that the calculated effects of longitudinal GBs do not appear in the experimental results at high gate voltage.

4 illus, 1 table, 20 ref

022549   Goyal S L;Mohindra R K (Dep of Appl Phys, Guru Jambheshwer Univ, Hisar-125 001) : Cross-sections of 14 MeV neutron induced reactions on some isotopes of chromium, zirconium and tin. Indian J pure appl Phys 2006, 44(3), 216-9.

Neutron induced reaction cross-sections of the isotopes ⁵²Cr, ⁵³Cr, ⁹⁰Zr, ⁹¹Zr, ⁹²Zr, ⁹⁴Zr, ¹¹⁶Sn, ¹¹⁸Sn and ¹²⁰Sn for (n.p), (n,n'), (n,∝) and (n, 2n) reactions have been evaluated at 14 MeV. The computations are based on the evaporation model considering the pre-equilibrium emission mechanism under some approximations. The computer codes ALICE-91, NX-1 and SC2N3N have been used. These cross-sections were also computed using the level density formula of Lang and Le Couteur with and without applying pairing energy correction. The compound nucleus theory based on Fermi gas and evaporation model with optical model potential parameters has been used. The neutron, proton and alpha penetrabilities and inverse reaction cross-sections have been computed using the computer code SCAT-2. The computed cross-sections have been compared with the available experimental values and the results are in fairly good agreement.

3 tables, 24 ref

022548   Gour M S;Khare P K;Singh R (Depart mem of Phys, Hindustan Coll of Sci & Technol, Farah, Mathura, Uttar Pradesh) : Charge decay characteristics of polystyrene. Indian J Phys 2006, 80(1), 89-93.

The charge decay behavior of polystyrene (PS) samples, = 40 μm in thickness, was investigated by means of transient currents (in charging and discharging mode) and thermally stimulated discharge currents (TSDC) measurements as a function of polarizing fields, and temperatures. The order of currents has been found to increase with increasing these parameters. The current-time characteristics have different values of slopes lying between 0.45 to 0.65 and 1.66-1.99. The TSDC thermograms of PS consist of a peak located around 60-85°C. Comparative studies of the isochronal characteristics (i.e. current-temperature plots at constant times) with the thermally stimulated discharge current, indicated a strong resemblance between two techniques. It is suggested that both the dipolar orientation due to molecular mechanism of motions with the side chains and space charges due to trapping of injected charge carriers in energetically distributed traps may be responsible for the observed currents.

5 illus, 21 ref

022547   Ghosh S;Thakur P;Salimullah M (Sch of Stud in Phys, Vikram Univ, Ujjain-456 010) : Dispersion and absorption of longitudinal electro-kinetic waves in ion-implanted semiconductor plasmas. Indian J pure appl Phys 2006, 44(3), 235-42.

Excitation of modified electro-kinetic modes and novel properties introduced due to the presence of negatively charged colloidal particles in otherwise compensated semiconductor plasma are investigated. A compact linear dispersion relation for the electro-kinetic waves in colloids laden semiconductor plasma has been derived by using multi-fluid analysis and Maxwell's equations. This dispersion relation has been studied for slow and fast electro-kinetic modes. The presence of charged colloids significantly modify the dispersion and absorption characteristics of all possible modes even though colloidal particles, because of their heavy masses do not participate in wave propagation.

5 illus, 30 ref

022546   Ghosh S;Thakur P (Sch of Stud in Phys, Vikram Univ, Ujjain-456 010, Email: drsanjayghosh@rediffmail.com) : Electro-kinetic wave spectrum in group-IV semiconductors: Effect of streaming carriers. Indian J pure appl Phys 2006, 44(2), 188-91.

The implanted ions in a group-IV semiconductor agglomerate to form nano-clusters (NCs) and some of them acquire negative charge which change the balance between electron-hole densities in an otherwise compensated semiconductor. An analytical study has been made on wave spectrum of electro-kinetic (EK) waves propagating through such medium. Using multi-fluid analysis and Maxwell's equations, a linear dispersion relation for the EK wave in such medium has been derived. This dispersion relation is used to study slow electro-kinetic wave phenomena and resultant instabilities numerically. The drift velocities of electrons and holes are found to be responsible for converting two aperiodic modes into periodic ones. They are also found helpful in reducing the absorption of all the four possible EK modes. It is found that choosing the proper values of applied electric field and wave number one may optimize the amplification coefficients of propagating modes.

2 illus, 16 ref

022545   Ghosh S;Khare P (Sch of Stud in Phys, Vikram Univ, Ujjain-456 010, Email: drsanjayghosh@rediffmail.com) : Acoustic wave amplification in ion-implanted piezoelectric semiconductor. Indian J pure appl Phys 2006, 44(2), 183-7.

An analytical study on excitation of acoustic waves and novel properties introduced by considering that the implanted ions in a group III-V crystal agglomerate to form nanoclusters (NCs) and some of them acquire negative charge in compensated piezoelectric semiconductor plasma has been presented. By using multi-fluid analysis and Maxwell's equations, a compact dispersion relation for the acoustic wave in a piezoelectric semiconductor has been derived. It is found that the presence of charged NCs not only modifies the wave spectrum but also alters the amplification characteristics even though NCs, on account of their heavy masses, are assumed to be stationary in the background.

2 illus, 19 ref

022544   Geethakrishnan T;Palanisamy P K (Cent for Laser Technology. Dep of Phys, Anna Univ, Chennai-600 025) : Optical phase-conjugation in erioglaucine dye-doped thin film. Pramana J Phys 2006, 66(2), 473-8.

Optical phase-conjugation (OPC) has been demonstrated in erioglaucine (acid blue 9) dye-doped gelatin films via continuous-wave degenerate four-wave mixing (DFWM) using a low-power He-Ne laser at 633 nm. DFWM and holographic processes are found to contribute to the observed phase-conjugate signal. A maximum phase-conjugate beam reflectivity of about 0.24 has been observed in these dye-doped gelatin films.

6 illus, 20 ref

022543   Geetha Bhavani A;Karthikeyan D;Lingappan N; Sreenivasa Rao A (Dep of Chem, Anna Univ, Chennai-600 025) : Disproportionation of 1,2,4-trimethylbenzene over bifunctional bimetallic catalysts. Indian J pure appl Phys 2006, 44(2), 177-82.

Zeolite-β and mordenite have been impregnated with 0.1 wt.% Pt and varying (0, 0.1. 0.3. 0.5 wt.%) amounts of Ni and reduced at 475°C. The line broadening XRD analysis indicates that the increasing Ni addition decreases the crysiallinity of zeolites. The TEM analysis indicates that the average metal particle size increases with increasing Ni addition. The states of Ni and Pt have been analyzed by ESCA. The acidity measurements by pyridine adsorbed FTIR spectroscopy show the occupation of some of the acid sites by the added Ni species. Disproportionation of 1,2,4-trimethylbenzene was carried out in the temperature range 250-400 °C and found that Ni addition up to 0.3 wt.% over 0.1 wt.% Pt/H-β and 0.1 wt.% over 0.1 wt.% Pt/H-MOR enhances the 1,2,4-trimetylbenzene conversion and disproportionation selectivity of the catalysts. Further. Ni addition above the threshold value leads to fall in activity and disproportionation selectivity drastically. Zeolite-β based Ni-Pt catalysts always show higher activity and selectivity than mordenite based catalysts.

5 illus, 2 tables, 15 ref

022542   Gautam A K;Vishvakarma B R (Dep of Electron Engng, Inst of Technol Banaras Hindu Univ, Varanasi-221 005, Email: brvish@bhu.ac.in) : MOS capacitor integrated microstrip antenna. Indian J Radio Space Phys 2006, 35(1), 47-53.

An MOS capacitor integrated microstrip antenna is proposed, in which the operating frequency of the rectangular microstrip antenna is electronically controlled with the bias voltage of the MOS capacitor. Theoretical investigations based on a modal cavity model are carried out for the MOS capacitor integrated microstrip antenna. The tuning range was found to be 4.6836 GHz (110.08 %) in comparison to that (76.08 %) reported earlier.

11 illus, 14 ref

022541   Dolia S N;Subhash Chander;Sharma M P;Sudhish Kumar (Dep of Phys, Univ of Raj, Jaipur-302 004) : Superparamagnetic behaviour of nano-particles of Ni-Cu ferrite. Indian J pure appl Phys 2006, 44(2), 169-72.

The nano-particles of Ni_0.8Cu_0.2Fe₂O₄ with a log-normal size distribution of the median diameter of 9 nm and standard deviation of 0.60 have been synthesized by the chemical co-precipitation method followed by annealing at 500°C. The cubic spinel structure in single phase has been confirmed by X-ray diffraction. Reduction in saturation magnetization has been explained on the basis that the magnetic moments in the surface layers, outside the core are in a state of frozen disorder. The dc magnetization is measured which show that the nano-particle sample is super-paramagnetic above the blocking temperature of 250 K. Secondly, the departure of fc curve from the zfc curve is suggestive of temporal relaxation.

4 illus, 19 ref

022540   Chaisi M;Maharaj S D (Astrophys and Cosmology Res Unit. Sch of Math Sci, Univ of KwaZulu-Natal, Durban 4041, South Africa) : New algorithm for anisotropic solutions. Pramana J Phys 2006, 66(2), 313-24.

Establishes a new algorithm that generates a new solution to the Einstein field equations, with an anisotropic matter distribution, from a seed isotropic solution. The new solution is expressed in terms of integrals of an isotropic gravitational potential; and the integration can be completed exactly for particular isotropic seed metrics. A good feature of the approach is that the anisotropic solutions necessarily have an isotropic limit. Finds two examples of anisotropic solutions which generalise the isothermal sphere and the Schwarzschild interior sphere. Both examples are expressed in closed form involving elementary functions only.

3 illus, 26 ref

022539   Chacko E;Linet J M;Priya S M N;Vesta C;Boaz B M;Das S J (Dep of Phys, Loyola Coll, Chennai-600 034) : Growth and microhardness studies of mixed crystals of (NH₄)₂ SbF₅ K₂SbF₅. Indian J pure appl Phys 2006, 44(3), 260-3.

Mixed crystals of NH_<4>)_<2> SbF_<5> K_<2>SbF_<5> an electro-optic material have been grown by isothermal evaporation technique. Powder X-ray diffraction method has been used for structural identification and determination of lattice parameters. Load dependent microhardness measurements on this crystal reveal the mechanical behaviour of the material. The work hardening co-efficient and the yield strength of the material were found to be 11.66 and 2.058 Mpa, respectively.

3 illus, 1 table, 17 ref

022538   Banerjee A;Harbola M (Laser Phys Div, Cent for Advd Technol, Indore-452 013, Email: banerjee@cat.ernet.in) : Van der Waals coefficients akali metal cluster and their size dependence. Pramana J Phys 2006, 66(2), 423-33.

Employs the hydrodynamic formulation of time-dependent density functional theory to obtain the van der Waals coefficients C₆ and C₈ of alkali metal clusters of various sizes including very large clusters. Such calculations become computationally very demanding in the orbital-based Kohn-Sham formalism, but are quite simple in the hydrodynamic approach. Shows that for interactions between the clusters of the same sizes, C₆ and C₈ scale as the sixth and the eighth power of the cluster radius, respectively, and approach their classically predicted values for the large size clusters.

2 illus, 6 tables, 29 ref

022537   Bandyopadhyay K;Rakshit G (NO, , 1/D, Bibhuti Apartment, Luby Circular Road, Hirapur, Dhanbad-826 001, Email: kbph@rediffmail.com) : Leptonic CP violation and neutrino mass in a three generation SU(2)_H gauge model. Indian J Phys 2006, 80(1), 67-70.

It is shown that with suitable Higgs field the lepton mass matrix in SU(2)_L x SU(2)_R x U(I)_B-L x SU(2)_H gauge model is identical with the mass matrix ansatz based on the permutation symmetry. The possibility of leptonic CP violation is discussed in terms of CP-violating rephasing-invariant quantity J¹_CP. The neutrino mass bounds are also mentioned on the basis of the mass matrix obtained.

8 ref

022536   Bafna M K;Sen P;Sen P K (Dep of Appl Phys, S G S Inst of Technol & Sci, 23, Park Road, Indore-452 003) : Effect of temperature on non-linear optical properties of InGaAs/GaAs single quantum dot. Indian J pure appl Phys 2006, 44(2), 152-6.

Based upon the semi-classical density matrix approach, a detailed theoretical investigation has been made to analyze the effect of temperature on non-linear optical properties of InGaAs/GaAs single quantum dot (QD). The temperature effects have been incorporated via temperature dependent (i) dephasing mechanism, (ii) band gap energy and (iii) population density. The semiconductor QD has been chosen to be small enough such that the confinement effect dominates over the Coulombic contribution. Detailed numerical estimates of the non-linear refraction and absorption properties have been made. Redshifts of the non-linear refraction and absorption peaks as well as reduction in the induced polarization are found to occur with increasing temperature. It has been revealed that the non-linear gain reduces at higher temperature.

3 illus, 16 ref

022535   Avinash V;Verma M K;Chandra A V (Dep of Phys, Indian Inst of Technol, Kanpur-208 016, Email: mkv@iitk.ac.in) : Field-theoretic calculation of kinetic helicity flux. Pramana J Phys 2006, 66(2), 447-53.

Applies perturbative field-theoretic technique to helical turbulence. In the inertial range the kinetic helicity flux is found to be constant and forward The universal constant KH appearing in the spectrum of kinetic helicity was found to be 2.47.

20 ref

022534   Ashtaputre S;Deshpande A;Ahmed M A;Marathe S; Kalele S;Chimanpure J;Urban J;Gosavi S W;Kulkarni S K (DST Unit on Nanoscience Dep of Phys, Univ of Pune, Pune-411 007, Email: skk@physics.unipune.ernet.in) : Integrating nano and microparticles. Indian J pure appl Phys 2006, 44(2), 107-12.

A variety of nanomaterials have been developed in last few years with interesting physico-chemical properties. Most of the attempts so far have been to gain understanding of this new class of materials and look for potential applications. This has lead to the formulation of some scaling laws to explain, reasonably well, the properties of nanomaterials. It is realized, however, that the nanomaterials are often too difficult to handle due to their chemical, thermal etc instabilities as well as smallness. There is now a growing interest to integrate nanoparticles with microparticles to get advantages of both the nano and micro world of materials.The synthesis and characterization of ZnO, CdSe, TiO₂ and SiO₂ nano to micro particles and about core-shell particles have been studied.

5 illus, 37 ref

022533   Anil Kumar C P;Thangara N (Equatorial Geophys Res Lab, Indian Inst of Geomagnetism, Krishnapuram, Maharajanagar (PO), Tirunelveli-627 011, Email: cpanil@iigs.iigm.res.in) : Refractive index structure constant from radar data. Indian J Phys 2006, 80(1), 37-41.

The work focuses on the measurement of refractive index structure constant from the backscattered signal strength. For this purpose. Authors have made use of the equatorial data measured by medium frequency (1.98 MHz) Partial Reflection Radar, located at Tirunelveli (8.7°N, 77.8°E, 0.3°N magnetic dip). This radar has been operated continuously by the Indian Institute of Geomagnetism; the data obtained with this radar have been providing valuable information on middle atmosphere dynamics. This is a preliminary study conducted in the equatorial region and the Partial Reflection Radar is not an efficient tool for turbulent studies, hence the estimation of refractive index structure constant of turbulence i.e. C²_n is very difficult. The refractive index structure constants for turbulence is calculated numerically and plotted with the vertical wind velocity. C²_n values show an enhancement during post sunset hours. It may be due to the fact that the plasma within the geomagnetic flux tube becomes unstable because of pre-reversal enhancement (E x B electrodynamic drift) and takes part in the up-welling process thus making turbulence within the volume.

3 illus, 1 table, 15 ref

022532   Ambujam K;Rajarajan K;Selvakumar S;Prem Anand D;Thomas P C;Sagayaraj P (Dep of Phys, Queen Mary's Coll, Chennai-600 004) : Growth and characterization of gel grown single crystals of cadmium mercury tetrathiocynate. Indian J pure appl Phys 2006, 44(3), 243-7.

Relatively large sized colourless transparent crystals of cadmium mercury tetrathiocyanate (CMTC) are grown at near ambient temperature using silica gel in straight test tubes in about one week time. Single crystal XRD studies have confirmed the structure of the grown crystals as tetragonal. The grown crystals are characterized by UV-Vis-NIR and FTIR studies. Kurtz powder technique is employed to confirm their non-linear optic (NLO) behaviour. Thermal analysis proves that CMTC is stable up to 200<144>C. Microhardness studies reveal that CMTC possesses high Vicker's hardness value. The dielectric measurement is carried out at room temperature and the variation of <101> with frequency has been studied.

6 illus, 19 ref

022531   Ahmed N K;Abbady A;El Arabi A M;Michel R;El Kamel AH;Abbady AG E (Phys Dep, Fac of Sci Qena South Valley Univ, Egypt, Email: abbady1965@yahoo.com) : Comparative study of the natural radioactivity of some selected rocks from Egypt and Germany. Indian J pure appl Phys 2006, 44(3), 209-15.

The radioactivity contents of various radionuclides in rocks play an important role in health physics and geo-scientific research. The naturally occuring radionuclides 2.26, Ra 2.3, Th and K 40 are the main sources of radiation in soil and rocks from which traditional building materials are derived. These radionuclides pose exposure risks externally due to their gamma-ray emissions and internally due to radon and its progenies, which emit alpha particles. The activity concentration (Bq/kg) in igneous and metamorphic rock samples from different locations in Egypt and Germany has been analysed. The concentration values of samples for 226, Ra 232, Th and K 40 were found in the range of 3.9 : 57.4, 3.2 : 53.4 and 202 : 1211 in Egypt and 5.1 : 76, 3.4 : 70 and 10 : 2070, respectively in Germany. Even though these radionuclides are widely distributed, their concentrations depend on the local geological conditions.

1 illus, 1 table, 20 ref

022530   Ahire R R;Sharma R P (Thin Film and Semicond Lab Dep of Phys, G T Patil Coll, Nandurbar-425 412, Email: ramphalsharma@yahoo.com) : Photoelectrochemical characterization of Bi₂S₃ thin films deposited by modified chemical bath deposition. Indian J Engng Mater Sci 2006, 13(2), 140-4.

For the photoelectrochemical (PEC) solar cell, the prime requirement is that photoelectrode/ photoanode should have bandgap close to the maximum in the visible spectrum. Bismuth sulphide (Bi₂S₃) is challenging material because of its midway bandgap (E_g=1.74 eV) and absorption coefficient of the order of 10⁴ cm^-1. Bismuth sulphide (Bi₂S₃) thin films of thickness about 0.14 μm have been prepared by using modified chemical bath deposition method onto glass and fluorine doped tin oxide (FTO) coated glass substrate under optimized conditions. The films are annealed at 200°C for 2 h in air. It is found that deposited films turn from amorphous to polycrystalline after annealing. The Bi₂S₃/NaOH-S-Na₂S/C cell has been fabricated by using Bi₂S₃ annealed films and their photoelectrochemical performance has been studied. It is found that Bi₂S₃ films are photoactive. However, conversion efficiency is low (0.056%) due to low series and high shunts resistance of Bi₂S₃ films.

7 illus, 16 ref

022529   Abouelaoualim D (L.P.S.C.M. Phys Dep, Fac of Sciences-Semlalia, BP:2390, 40000, Marrakech, Morocco, Email: abouelaoualim_d@hotmail.com) : Electron-confined LO-phonon scattering in GaAs-Al_0.45Ga_0.55 As superlattice. Pramana J Phys 2006, 66(2), 455-65.

Develops a theoretical model to the scattering time due to the electron-confined LO-phonon in GaAs-Al_{xGa1-x. As superlattice taking into account the sub-band parabolicity. Using the new analytic wave function of electron miniband conduction of superlattice and a reformulation slab model for the confined LO-phonon modes, an expression for the electron-confined LO-phonon scattering time is obtained. In solving numerically a partial differential equation for the phonon generation rate. The results show that for x = 0.45, the LO-phonon in superlattice changes from a bulk-like propagating mode to a confined mode. The dispersion of the relaxation time due to the emission of confined LO-phonons depends strongly on the total energy.}

9 illus, 40 ref

021618   Varshney N K;Dharmvir Singh (Dep of Math, S.V. Coll, Aligarh, U.P) : Effect of mass transfer on MHD free convective flow of a dusty gas through a porous medium induced by the motion of a semi-infinite flat plate moving with velocity decreasing exponentially with time. Indian J Theor Phys 2005, 53(4), 325-34.

The problem is concerned with the "Effect of mass transfer on MHD free convective flow of a dustry gas through a porous medium induced by the motion of a semi-infinite flat plate moving with velocity decreasing exponentially with time". The effect of M (Magnetic parameter), K_l (permeability parameter), S_e (Schimdt number) with the time on velocity and concentration distributon of incompressible dusty gas and dust particles is discussed graphically with the help of the tables.

2 illus, 2 tables, 17 ref

021617   Varghese T;Balakrishna K M;Siddappa K (Dep of Phys, Nirmala Coll, Muvattupuzha-686 661, Kerala, Email: surajthomas@sancharnet.in) : Gamma ray compton profiles of dysprosium and holmium. Indian J Phys 2006, 80(3), 289-92.

The electron momentum distribution and Compton profiles of rare earth elements dysprosium (Dy) and holmium (Ho) were measured using HPGe detector. The measurements were carried out on a high purity thin elemental foil using 59.54 keV gamma rays from Am-241. The data was recorded and analyzed using a 4 K multichannel analyzer. The experimental data was corrected for instrumental resolution effects, sample absorption, energy dependence of the differential Compton cross section and double scattering. the results are presented along with theoretical free atom values. The present experimental Compton profiles of Dy constitute the first measurement.

1 illus, 1 table, 16 ref

021616   Stalin Mango Gibson M;Lawrence N (Dep of Phys, Mepco Schlenk Engng Coll, Sivakasi, Virudhunagar-626 005) : Pressure dependent hydrogen isotopic diffusion in Cr_0.7Fe_0.3 alloy. Indian J Phys 2006, 80(3), 235-40.

Using Born-von Karman formalism including upto sixth nearest neighbours interaction, the phonon dispersion has been calculated theoretically in the substitutional bcc alloy CrFe_0.3. It is found to be in good agreement with the experimental results. The Mean Square Displacement (MSD) of surrounding host atoms with hydrogen and deuterium interstitials are investigated using Green's function technique and scattering matrix formalism from normal pressure to 2.5 GPa in the temperature range of 500 K-1250 K. The MSD of atoms surrounding the interstitial are found to be smaller than those of the host crystal atoms. Using reaction coordinate technique, the diffusion parametemrs are calculated for the above mentioned temperature and pressure ranges. It is observed that the activation energy for the diffusion of ²H is twice as that for H diffusion and the diffusivity ration D_H/D_2H is always greater than unity and it is temperature and pressure dependent.

5 illus, 1 tables, 16 ref

021615   Srivastava S K (NO, Cent for Advd Technologies, Jagadhri, Yamunanagar-135 003, Email: sanjeevsrivastava1980@rediffmail.com) : Pressure dependence of gruneisen ratio of MgO at high temperatures. Indian J Phys 2006, 80(3), 247-51.

In the present communication, a simple approach is established to predict dependence of Gruneisen ratio of Mgo in high temperature domain. the calculations are shown with the help of more accurate input data, suggested by Jacobs and Oonks [Phys. Chem. Chem. Phys. 2 2641 (2000)]. The predicted values of compression dependence of the Gruneisen parameter are compared with those evaluated by Cynn et al [J. Phys. Chem. 99 7813 (1995)]. The vinet equation of state (EoS) is used to convert compression to corresponding pressure. It is found that the Gruneisen parameter decreases with compression along an isotherm. the present analysis is useful to study the anharmonic properties of MgO.

4 tables, 33 ref

021614   Srivastava R C;Srivastava R;Leutloff D (Math Dep, D.D.U. Gorakhpur Univ, Gorakhpur) : Shock wave in two dimensional two species flow. Indian J Theor Phys 2005, 53(4), 277-94.

Propagation of shock wave is investigated in two dimensional two species flow. the motion of inviscid two species fluid may be modeled by Eulerian system of equation. the conservative form of Eulerian system used for the solution of the problem gives the strong oscillations and other computational inaccuracies near the material interfaces. These are due to erroneous pressure fluctuation generated by the conservation wave model. this problem does not occur in one dimension single specy computation and arrises only in the presence of several species. therefore a non-conservative formulation is proposed which completely eliminate oscillation. the numerical algorithm is used and distribution of flow variables are represented by the graphs.

5 illus, 13 ref

021613   Singh Chandel R C;Singh Y K (Dep of Math, D.V. Postgrad Coll, Orai-285 001) : Two boundary value problems. Indian J Theor Phys 2005, 53(4), 339-50.

We evaluated an integral involving multivariable polynomials of Srivastava and the H-function of several complex variables of Srivastava and Panda and then makes its applications to solve two boundary value problems on (i) heat conduction in a rod (ii) deflection of vibrating string, under certain conditions and to establish an expansion formula involving product of above polynomials and H-function of several complex variables. In the last, some interesting special cases are also discussed.

021612   Sawhney N;Dua A;Chandan A;Bharti A;Khosa S K (Dep of Phys, Univ of Jammu, Jammu-180 006, Jammu & Kashmir, Email: arunbharti_2003@yahoo.co.in) : Spectoscopy of lower spin states in tellurium isotopes with the inclusion of hexadecapole interaction. Indian J Phys 2006, 80(3), 283-288.

Variation After Projection (VAP) calculations in conjenction with Hartree Bogoliubov (HB) ansatz have been carried out for ^110-116Te isotopes. In this framework, the Yrast spectra, B(E2) transition probabilities, quadrupole deformation parameter (β₂) and occupation numbers for various shell model orbits have been obtained. The results of the calculation give an indication that it is important to include the hexadecapole-hexadecapole component of the two-body interaction for obtaining various nuclear structure quantities in these tellurium isotopes.

1 illus, 4 tables, 27 ref

021611   sathyaprakash B S (Sch of Phys and Astr, Cardiff Univ, Cardiff, CF24, 3YB, UK, Email: B.Sathyaprakash@asro.cf.ac.uk ) : Gravitational radiation - in celebration of Einstein's Annus Mirabilis. Curr Sci 2005, 89(12), 2129-39.

Two of Einstein's 1905 papers were on special theory of relativity. Although general relativity was to come a decade later, it was special relativity that was responsible for the existence of wave-like phenomena in gravitation. A hundred years after the discovery of special relativity we are poised to detect gravitational waves and the detection might as well come from another inevitable and exotic prediction of relativity, namely black holes. With interferometric gravitational wave detectors taking data at unprecedented sensitivity levels and bandwidth, we are entering a new century in which our view of the Universe might be revolutionized yet again with the opening of the gravitational window. The current generation of interferometric and resonant mass detectors are only the beginning of a new era during which the gravitational window could be observed by deploying pulsar and microwave background radiation.

3 illus, 52 ref

021610   Sarkar S (Rudolf Peierls Cent for Theoretical Phys, , 1 Keble Road, Oxford OXI 3NP, UK, Email: s.sarkar@physics.ox.ac.uk) : Einstein's universe: The challenge of dark-energy. Curr Sci 2005, 89(12), 2120-8.

From an observational perspective, cosmology is today in excellent shape-Ore can now look back to when the first galaxies formed <126> 1 Gyr after the Big Bang, and reconstruct the thermal history back to the primordial nuclepsynthesis era when the universe was <126> 1 s old. However recent deep studies of the Hubble diagram of Type Ia supernovae indicate that the expansion rate is accelerating, requiring the dominant component of the universe to have negative pressure like vacuum energy. This has been indirectly substantiated through detailed studies of angular anisotropies in the cosmic micro wave background and of spatial correlations of the large-scale structure of galaxies which also require most of the matter component to be non-baryonic. AI- through there are plausible candidates for the constitu-ent of the dark matter in physics beyond standard Model (e.g.supersymmetry),the energy scale of the required 'dark energy' is <126> 10^-12 GeV, well below any known scale of fundamental physics. This has refocussed attention on the notorious cosmological constant problem at the interface of general relativity and quantum field theory. It is likely that the resolution of this issue will require fundamental modifications to Einstein's ideas about gravity.

6 illus, 48 ref

021609   Rastogi R P;Ishwar Das;Sharwan Kumar (DDU Gorakhpur Univ, , Gorakhpur, Email: kumarskmittal@yahoo.com) : Complex oscillations and chaos. Natn Acad Sci Lett 2005, 28(9-10), 303-12.

A readable account of complex oscillations and chaos has been presented. Types of complex oscillations, concept of limit cycles in case of periodic and chaotic oscillations have been discussed. Deterministic choas has been dealt in detail along with methods for characterization of chaos. Routes to chaos from periodic behaviour have also been indicated. Comments have been made of modeling and test of reliability of chaotic behaviour. Methods for controlling chaos have also been elaborated. Relevance of chaos in physiology and communication systems has been pointed out.

11 illus, 1 table, 15 ref

021608   Podlaha M F (NO, , D-94089, Neureichenau, Germany) : On the probabilistic quantum mechanics. Indian J Theor Phys 2005, 53(4), 335-8..

The "exchange integrals" of the probabilistic quantum mechanics do not and cannot give any explanation of the chemical forces. The Kursunoglu³ theory explains them and it shows that there is a unity between the chemical and the nuclear forces. Relation of the kursunoglu theory to my theory with Sjodin about the two kinds of matter waves is discussed. Further, it is shown that, at the chain reaction of the U²³⁵₉₂, four and not three neutrons play a role.

5 ref

021607   Narlikar J V (Inter-University Cent for Astr and Astrophys, Post Bag 4 Ganeshkhind, Pune-411 007, Email: jvn@iucaa.ernet.in) : Einstein's legacy: Relativistic cosmology. Curr Sci 2005, 89(12), 2114-19.

Review gives a historical account of how cosmology has developed since the 1917 paper of Albert Einstein. Today it is a frontier level science drawing on contemporary astronomy as well as contemporary physics, stretching both as far as extrapolations will permit. Thanks to numerous observations at different wave-lengths, cosmologists today have their plates full. Extrapolations of laboratory tested physics are called for to understand all information within the framework of a standard model. The success and shortcomings of this approach are briefly discussed against the historical backdrop.

32 ref

021606   Mukherjee A;Karanjai S (Dep of Math, North Bengal Univ, Darjeeling, West Bengal-734 430) : Solution of the equation of transfer with carlstedt and mullikin's phase function. Indian J Theor Phys 2005, 53(4), 301-15.

The double interval spherical harmonic method introduced by Wilson and Sen has been used to solve the equation of radiative transfer in the case of anisotropically scattering atmosphere with phase function given by Carlstedt and Mullikin.

3 tables, 11 ref

021605   Mukesh Kumar (NO, , Diwakar Bhawan, Mishra Tola, Gannipur, Muzaffarpur-842 001, Email: mukbihar@yahoo.com) : Measurement of complex dielectric constant of sand, silt and clay samples at 12 GHz. Int J chem Sci 2005, 3(4), 655-62.

Experimental investigation has been carried out to measure the complex dielectric constant of sand, silt and clay samples at 12 GHz. For this purpose, the propagation of electromagnetic wave through these samples has been utilized. Attempt has also been made to observe the effect of moisture content in these samples. The complex dielectric constant was found to increase with increasing percentage of moisture content in each sample. The effective increase in complex dielectric constant with same moisture content in sandy sample is greater than other two samples.

3 illus, 3 tables, 6 ref

021604   Mishra M C;Jha H K (Dep of Phys, Millat Coll, Darbhanga, Bihar) : Analysis of optimization of circular aperture distributions. Indian J Theor Phys 2005, 53(4), 295-300.

Deals with a simulated annealing method for maximizing the efficiency of a circular aperture generating a double difference pattern. here the non-monotonicity of the excitation amplitude distribution is minimized. The process is computer efficient taking about a few minutes.

3 illus, 1 table, 8 ref

021603   Makarov I S (NO, , Independent Researcher, P.O. Box-3447, Ramat Gan-52136, Israel) : Evaluation of parameters and characteristics of ether. Indian J Theor Phys 2005, 53(4), 265-76.

There have been evaluated the normalized energy spectrum of ether and its correlation function. The latter consists of two parts : a small ascending part, determining the zone of uncertainty and corresponding to the process of corpuscular interaction of virtual electrons and positrons, and a large exponentially descending part, corresponding to the process of photon exchange. These result suggest the mean radius of the electron in the state of rest to be over one hundred times less than the so-called electronic radius r_e promulgated by modern phyiscs.

5 illus, 3 tables, 4 ref

021602   Kanse K S;Chavan S D;Mali C S;Kumbhakhane A C;Mehrotra S C (Sch of Phys Sci, Swami Ramanand Teerth Marathwada Univ, Nanded-431 606) : Structural study of methanol-water mixture from dielectric parameters. Indian J Phys 2006, 80(3), 265-9.

Binary mixtures of water and methanol over entire range of composition have been studied by hydrogen-bonded model suggested by Luzar. The Luzar theory is applied to determine the molecular parameters and correlation terms for the mixture. the theoretical and experimental values of static dielectric constant and excess permittivity are reported. The shape of theoretical curve matches with the experimental ones over the whole concentration of the water in methanol. the negative values of excess dielectric parameter suggests that the addition of methanol to water may creat multimeric structure.

3 illus, 3 tables, 25 ref

021601   Kandpal S;Rai A K;Kushwaha R P S (Dep of Phys, G B Pant Univ of Agric and Technol, Pantnagar-263 145, Email: kandpalseema_26@rediffmail.com) : Effect of CdS on alum using photoacoustic spectroscopy. Indian J Phys 2006, 80(3), 297-9.

Photoacoustic (PA) sapectra of CdS, alum and CdS-despersed alum are recorded in a single beam PA spectrometer, using 1000 W tungsten halogen lamp. PA spectra of pure CdS and pure alum show an absorption edge at 515 nm, 1164 nm. PA spectra of 5% CdS-dispersed alum, 10% CdS-dispersed-alum and 15% CdS-dispersed alum show absorption edge at 2170 nm, 1650 nm and 1345 nm, respectively. Using these absorption edges, we have calcualted the energy bank gap and our result revealed that the energy band of CdS-dispersed alum is less than its constituents and energy bank gap increases as we increase the amount of CdS.

5 illus, 1 table, 8 ref

021600   Jadhao B U;Banmeru P K;Patil P B (NO, Shri Shivaji Coll, Parbhani-431 401, Email: pkbanmeru@yahoo.co.in) : A novel method for the measurement of dielectric constant at microwave frequency by using strip line embedded in rectangular waveguide. Indian J Phys 2006, 80(3), 271-4.

This paper deals with the introduction of a new method of measurement of dielectric constant at microwave frequency. The variation of cut-off frequency of strip line embedded in rectangular wave-guide is taken as a parameter for calibration of dielectric constant and a new method for measuring dielectric constant is suggested. By placing the material sample at various locations, theoretically the changes in cutoff frequency of fundamental and first overtone are worked out and the location of maximum changes is selected for further calculations. Using Finite Element Method (FEM) and sample of different dielectric constant located at the selected place, the variations in cut-off frequencies are calculated. Using these variations, a calibration curve is established and a new method of measurement of dielectric constant is suggested.

3 illus, 2 tables, 5 ref

021599   Gribkov V A;Dubrovsky A;Orlova M A;Seholz M (NO, Inst of Plasma Phys and Laser microfusion, Warsaw, Poland, Email: Gribkovv@ifpilm.waw.pl) : Opportunities afforded by new generation of pulsed radiation sources in flash radiation physics and chemistry. Res J Chem Envir 2005, 9(4), 11-19.

Discusses new generation of devices irradiating very short high-energy pulses of ionizing radiation. Various perspectives emerged in radiation physics and chemistry owing to appearance of them dictate to use the term "flash radiation chemistry" in its perfect sense only in a particular condition. Viz. two prerequisties (spatial and temporal) must be fulfilled: ovverlapping of individual effective interaction micro-volumes (e.g. spurs and blobs at water electrolysis) and it has to be realized during a time interval (radiation pulse duration) that is less compared with the corresponding physical-chemical process. Namely in this situation it appears to be possible to change reaction rate, to influence reactions at kinetic level, as well as to realize a number of synergetic (collective) effects. The non-stationery and non-diffusive development of chemical processes has to be counted as an intrinsic feature of the perfect flash radiation chemistry.

3 illus, 1 table, 25 ref

021598   Gopalakrishna G S;Mahesh M J;Ashamanjari K G (Dep of Stud in Geol, Univ of Mysore, Manasagangotri, Mysore-570 006, Email: gopalakrish2004@yahoo.com) : Magnetic and thermal characterisation of Na₂NiP₂O₇ crystals. Indian J Phys 2006, 80(3), 293-6.

Na₂NiP₂O₇ crystals were synthesized by hydrothermal technique and characterized by DTA/TGA, XRD, FTIR and measured magnetic property. Na₂NiP₂O₇ crystals are crystallized in monoclinic system. DTA/TGA results revealed a phase transition at 524°C and magnetically, it is a frequency-dependent paramagnetic mateial and the thermal treatment to the material has resulted in change of magnetic properties from paramagnetic to ferrimagnetic.

5 illus, 1 table, 15 ref

021597   Ganguly N;Iyer K N (Dep of Phys, St. Xavier's Coll, Ahmedabad-380 009, Gujarat) : Effect of E1 Nino southern oscillation on the ozone concentration of Indian cities. Indian J Phys 2006, 80(3), 229-34.

The effect of E1 Nino southern oscillation (ENSO) on the Total, Tropospheric and Stratospheric ozone concentration from 1980 to 2003 at Kanyakumari (8°N, 77.6°E), (22.3°N, 70.8°E), Delhi (28.3°N, 77.3°E) and Srinagar (34°N, 75°E) has been studied using the data obtained from total Ozone Mapping Spectrometer (TOMS) and Tropospheric Ozone Residual method (toR). the effect of ENSO on the seasonal variation of Total ozone at these four stations has been investigated. the observed results and possible causes for the breakdown in ozone-ENSO relations in certain years, have also been discussed.

10 illus, 14 ref