003078   Rout S K;Badapanda T;Sinha E;Panigrahi S (Physics Dep, National Institute of Technology, Rourkela-769 008) : Dielectric study on sol gel derived BTZ film deposited by spin coating technique. Indian J Phys 2007, 81(1), 149-53.

Barium zirconium titanate thin films are attractive candidates for dynamic random access memories and tunable microwave devices. Barium zirconate titanate Ba(Ti_1-xZr_x)O₃ (BTZ, x = 0.0, 0.2, 0.4) ceramics have been prepared by a sol-gel process. X-Ray diffraction studies confirmed that the films of BTZ are in crystalline form and of single phase. The SEM study shows that the films of homogeneous microstructure and Zr content strongly influence the grain size of the film. The grain size decreased and the microstructure became dense when substitute Zr for Ti. The room temperature dielectric study shows that the permittivity as well as dielectric loss tangent decreases with increase in Zr-content in the film. The ac conductivity was evaluated from dielectric data and is found to decrease with increase in Zr-concentration.

4 illus, 7 ref

003077   Reddy B S;Reddy G;Reddy P Y;Reddy K R (Physics Dep, Osmania University, Hyderabad-500 007, Email: yadagirireddy@yahoo.com) : Radon and thoron equilibrium factors for the dwellings of Khammam district, Andhra Pradesh. Chem envir Res 2006, 15(4), 265-70.

Indoor radon, thoron and their progeny levels were estimated in the dwellings of Khammam district, Andhra Pradesh using twin-chamber cup dosimeters with solid state nuclear track detectors (LR-115). With these estimated concentration levels the equihorium factors were calculated The radon equilibrium factors were found to vary between 0.013 and 0.706 with an annual average of 0.28±0.19, while for thoron these are ranged between 0.001 and 0.391 with an annual average of 0.10±0.11. These equilibrium factors are comparable to the equilibrium factors of other locations in India, but are low compared to many cold countries, which may be because of good ventilation in rural-urban atmosphere and temperature. The seasonal variation of equilibrium factors and their variations with the different types of dwellings are also discussed.

4 illus, 1 table, 7 ref

003076   Rautray T R;Vijayan V;Panigraahi S (Physics Dep, NIT, Rourkela-769 008) : Synthesis of hydroxyapatite at low temperature. Indian J Phys 2007, 81(1), 95-8.

(NH₄)₂HPO₄ and CaCI₂ were used as the P and Ca precursors for the synthesis of pure, stable, stoichiometric, crystalline hydroxyapatite at low temperature. The synthesized sample thus obtained was studied using energy dispersive X-ray fluorescence, X-ray diffraction, and thermogravimetric analysis. X-Ray diffraction analysis showed different phases of hydroxyapatite, energy dispersive X-ray fluorescence analysis confirmed the Ca/P, while thermogravimetric analysis showed the stability of the synthesized hydroxyapatite.

3 illus, 11 ref

003075   Rautray T R;Mishra S;Patnaik S K;Vijayan V; Panigrahi S (Physics Dep, NIT, Rourkela-769 008) : Analysis of human bone and teeth. Indian J Phys 2007, 81(1), 99-102.

The trace element analysis of four human bone samples of an individual of age 54 who died of an accident, were collected from different parts (tibia, parietal and occipital bone) of the human body by autopsy and analysed by particle induced X-ray emission technique. Similariy, twenty-seven healthy human teeth samples from twelve individuals of the age group 35-57, were carried out by energy dispersive X-ray f.luorescence spectroscopic technique at Institute of Physics, Bhubaneswar, India. Elements like P, S, CI, K, Ca, Mn, Fe, Cu, Zn, Sr and Pb were quantified in the human bone and teeih samples. The role and uniformity of the trace elements, present in all the samples, were presented and its effect on the statistical distribution of their concentrations is discussed.

2 illus, 7 ref

003074   Rani A;Kumar A;Singh S (Physics Dep, Guru Nanak Dev University, Amritsar-143 005, Email: surinder51@yahoo.com) : Natural radioactivity measurements in some Indian building materials. Chem envir Res 2006, 15(4), 257-64.

Deals with the radioactivity measurements of some Indian building materials using gamma ray spectrometry. The activity concentration obtained for ²²⁶Ra, ²³²Th and ⁴⁰K (ranged from 8.3 to 88.47, 8.45 to 95.29 and 23.43 to 155.46 Bq kg^-1, with the mean values of 42.57, 34.85 and 63.25 Bq kg^-1 respectively. To assess the radiological hazard of the natural radioactivity in the samples, the radium equivalent activity, the absorbed dose rate and the external hazard index were also calculated. The study yields an annual effective dose equivalent in the range of 0.6 to 11.73 x 10^-5 Sv with a mean value of 5.77 x 10^-5 Sv. The results suggest that the use of such building materials in the construction of domestic dwellings or workplaces in India is unlikely to give rise to any significant radiation exposure to the occupants. The uranium concentration in a few of the collected building materials was also calculated using fission track registration technique and the values ranged from 0.69 to 2.28 ppm.

1 illus, 5 tables, 14 ref

003073   Raju C L;Rao J L;Reddy B C V;Veera Brahmam K (Advanced Systems Laboratory, , Kanchanbagh, Hyderabad-500 058, Email: kveerabrahmam@rediffmail.com) : Thermal and IR studies on copper doped polyvinyl alcohol. Bull Mater Sci 2007, 30(3), 215-18.

5 mol% PVA :x mol% Cu²⁺ polymer films were prepared by casting process. Thermal transitions and thermal degradation of samples with respect to copper concentration were studied by differential scanning caiorimetry (DSC) and thermogravimetric analysis (TGA), respectively. Increase in glass transition temperature as a function of copper concentration shows a strong branching and steric effects in copper doped PVA complexes. Thermal degradation of films to an extent of 4-5% was found with an increase in copper content. FTIR spectrum of PVA doped Cu²⁺ ions indicate the presence of O-H, C-H, C=C and C-O groups.

3 illus, 2 tables, 18 ref

003072   Rajendra Prasad (Appied Physics Dep, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh-202 002, Email: rajendraprasad1@rediffmail.com) : SHI ion induced modification in free volume in polycarbonate through positron annihilation and gas permeation. Chem envir Res 2006, 15(4), 192-202.

Interest in ion beanm modification of the polymers has increased in recent years due to ion induced modifications and the availability of swift heavy ion beams from accelerators. The damaged region of the latent track due to passage of swift heavy ion in a polymeric material contains amorphous material with highest degree of disorder, resulting into the change of its tree volume properties and can be characterized by positron annihilation lifetime spectroscopy (PALS) and gas permeation. PALS is capable of probing free volume through ortho positronium (o-Ps) pick off lifetime which has a strong correlation with the size of the free volume. Gas permeation properties of the polymeric materials are strongly correlated with its micro structure (free volume hole concentration and their size distribution). By selective etching it is possible to enlarge the latent tracks and gas separation properties of polymeric membranes can be improved significantly by modifying it by swift heavy ion irradiation. Makrofol -KG polycarbonate widely used for ionographic studies was irradiated by swift heavy ions and ion induced modifications were studied by PALS and gas separation. The results are interpreted in terms of change in free volume. Gas separation permeability also indicates an increase in the free volume in polycarbonate samples irradiated to lower fluencies.

2 illus, 3 tables, 25 ref

003071   Rafique S M;Ashwani Kumar (University Physics Dep, T M Bhagalpur University, Bhagalpur-812 007, Email: sm_rafq@yahoo.com) : Thermodynamic properties and alloying behaviour of liquid binary alloy: CdZn. Indian J Phys 2007, 81(1), 35-9.

The complex formation model first proposed by Bhatia and Hargrove assumes the existence of chemical complexes or pseudomolecules in liquid binary alloys. On the basis of this concept Singh and his coworkers have studied various thermodynamical properties of different binary alloys. Also studied different alloys within this framework. Envisages the study of some thermodynamic properties viz., Gibbs free energy of mixing (G_M), enthalpy of mixing (H_M) and entropy of mixing (S_M) of CdZn binary alloy. The results are in reasonable agreement with experiment and throw light on the ionic interactions of the constituent atoms leading to the alloying behavior of the alloys under investigation.

2 illus, 9 ref

003070   Prasad K;Lily;Kumari K;Suman C K (Physics Dep, T M Bhagalpur University, Bhagalpur-812 007, Email: k_prasad65@yahoo.co.in) : AC impedance analysis of modified PbTiO₃ ceramic. Indian J Phys 2007, 81(1), 103-8.

Single phase tetragonal perovskite ceramic of Pb_0.76Ca_0.24Co_0.02W_0.02 Ti_0.96O₃ was prepared by a high temperature solid-state reaction method. Dielectric studies show the anomaly (T_c) at 256°C at 1 kHz. Complex impedance analysis indicated the dielectric relaxation to be polydispersive non-De bye type. The ac conductivity obeys the Joncher's universal power law and the dispersion in conductivity was observed in the lower frequency region.

4 illus, 18 ref

003069   Prasad G;Prasad Y;Gusain G S;Ramola R C (Physics Dep, H.N.B. Garhwal University, Badshahi Thaul Campus, Tehri Garhwal-249 199, Email: ganeshraturi7@yahoo.com) : Measurement of radon, thoron and their daughter products in Budhakedar homes. Chem envir Res 2006, 15(4), 238-41.

Radon, thoron and their daughter products were measured in the houses of Budhakedar for four different seasons (autumn, winter, summer and rainy) by using LR-115 Type II plastic track detector in twin cup radon dosimeter. The concentrations of indoor radon, thoron and radon progeny in the study area found to vary from 7 Bq/m³ to 137 Bq/m³ 4 Bq/m³ to 160 Bq/m³ and 0.38 mWL to 9.38 mWL, respectively distributed over four seasons. The radon and progeny concentrations were found maximum in winter and minimum in summer. However, thoron values were found maximum in rainy and minimum in summer. Detailed analysis of the effects of seasonal variation on radon, thoron and their decay products inside the houses are reported.

1 table, 18 ref

003068   Patel A N;Trivedi P;Oza A T (Phys Dep, Sardar Patel Univ, Vallabh Vidyanagar-388 120) : Infrared spectra of some ternary organic conductors based on benzidine as a donor. Indian J Phys 2006, 80(12), 1201-7.

The ternary organic charge transfer (CT) complexes namely benzidine-chloranil-₂, benzidine-DDQ-I₂, benzidine-TCNQ-I₂, and benzidine -TCNE-I₂, have been studied with infrared spectroscopy. Three-band model (two conduction band and one valence band) is concluded on the basis of two absorption edges. The ternary CT complexes differ from heavily doped semiconductors and organic alloys. Neutral-to-ionic transition model may be employed. Free carrier absorption reveals scattering of charge carriers by mainly ionized impurities, i.e. by 1₃- ions at disordered sites. Band tailing reveals disordered nature of materials. Nature of transitions based on absorption function also reveal weakly disordered materials.

5 illus, 2 tables

003067   Panda S K;Rout G C (NO, K D Science College, Pochilima, Hinjilcut, Orissa, Email: skp@iopb.res.in) : Superconductivity and antiferromagnetism gaps in cuprates. Indian J Phys 2007, 81(1), 55-61.

The high T_c superconductor exhibits very interesting co-existence of anti-ferromagnetism (AFM) and superconductivity (SC) in its doped state. The electron doped Nd- and hole doped La- cuprate systems show varieties of exotic properties. Reports a theoretical model to explain the origin of co-existence of SC and AFM gaps in the doped systems through self-consistent numerical analysis of both the gaps and their corresponding density of states (DOS). The impurity f-level of the Nd and La lie on the Fermi level (ε_F = 0) and there exists a weak hybridization between the f-level and the 3d electron of copper. The copper sites are represented by two sub-lattice sites 1 and 2 to simulate insulating sub-lattice staggered magnetic field. The DOS shows the interplay of SC, AFM and hybridization gaps for different parameters at various temperatures. Further the various amplitudes are calculated to investigate the temperature gap anomalies. The results are discussed.

3 illus, 5 ref

003066   Padma Kumar P;Balasubramaniam K;Krishnamurthy C V (Mechanical Engineering Dep, CNDE, Indian Institute of Technology Madras, Chennai-600 036, Email: ppkumar@mail.com) : Determination of transmission spectra using ultrasonic NDE. Trans Indian Inst Metals 2006, 59(2), 181-4.

Reliable inversion of elastic properties of materials from ultrasonic wave propagation data is an attractive non-destructive characterisation method requiring good quality ultrasonic transmission data. Discusses the goniometry-based through transmission experiments on plate samples of various thicknesses using a wide-aperture PVDF receiver that provides good quality transmission data over a wide range of angles. This was verified with metal and composite samples. The dispersive characteristics, evaluated from the measured transmission data, were verified by comparing with the theoretical dispersion curves for the samples. A good correlation was found between the theoretical predictions and experimental results on using a wide-aperture receiver.

5 illus, 5 ref

003065   Narula A K;Goyal S K;Nain M;Chauhan R P; Chakarvarti S K (Physics Dep, RKSD College, Kaihtal, Haryana, Email: anilnarula_ktl@yahoo.com) : Radon and its progeny measurements in some dwellings using solid-state nuclear track detectors. Chem envir Res 2006, 15(4), 283-6.

Radon and its progeny are the major contributors in the radiation dose received by general population of the world. It has been estimated that the radon and its progeny constitutes more than 50% of the dose equivalent received by general population from all sources of radiation, both naturally occurring and man-made. Radon (²²²Rn), a progeny of ²³⁸U, is a colourless, odorless noble gas, which is radioactive, and causes health hazards not only to uranium miners but also people living in normal houses and buildings. In the work radon arid its progeny concentration has been measured in different dwellings in the districts of Hisar, Rohtak and Kaithal in Haryana. The radon thoron twin dosimeter cups are being used for the study. Three pieces or LR-115 solid-state nuclear track detectors are fixed in the dosimeters and are suspended in the dwellings for three months. One gives radon, thoron and progeny concentration, second gives radon and thoron concentration while the third gives only the radon concentration. The aim of study is the possible-health risk assessment in the dwellings under consideration.

1 table, 6 ref

003064   Nandi S K;Chakraborty S;Bera M K;Maiti C K (Electronics and ECE Dep, Indian Institute of Technology, Kharagpur-721 302, Email: ckm@ece.iitkgp.ernet.in) : Structural and optical properties of ZnO films grown on silicon and their applications in MOS devices in conjuection and ZrO₂ as a gate dielectric. Bull Mater Sci 2007, 30(3), 247-54.

Photoluniinescence (PL) properties of undoped ZnO thin films grown by rf magnetron sputtering on silicon substrates have been investigated. ZnO/Si substrates are characterized by Rutherford backscat-tering (RBS), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and X-ray photoelection spectro-scopy (XPS). ZrO₂ thin films have been deposited on ZnO using microwave plasma enhanced chemical vapour deposition at a low temperature (150°C). Using metal insulator semiconductor (MIS) capacitor structures, the reliability and the leakage current characteristics of ZrO₂ films have been studied both at room and high temperatures. Schottky conduction mechanism is found to dominate the current conduction at a high temperature. Good electrical and reliability properties suggest the suitability of deposited ZrO₂ thin films as an alternative as gate dielectric on ZnO/n-Si heterostructure for future device applications.

14 ref

003063   Nain M;Chauhan R P;Kant K;Chakravarti S K (Physics Dep, Government College, Karnal, Haryana) : Alpha radioactivity measurements in tobacco leaves. Chem envir Res 2006, 15(4), 348-53.

"Smoking is hazardous to your health", warning labels such as this appear on every pack of cigarettes sold in the country. The link between cigarette smoke and cancer has long been established. Smokers are ten times at greater risk of developing lung cancer than that of non-smokers. Tobacco plants were grown using different types of chemical fertilizers in different amounts just before the plantation is done in some cases while after an interval of one month in other cases. The alpha radioactivity of the leaves of these plants was measured using plastic track detectors LR-115 Type-II manufactured by Kodak. Measurement of track densities (track cm^-2 day^-1) shows a variation from 152 track cm^-2 day^-1 to 38.6 track cm^-2 day^-1 on the upper face and 20.7 track cm^-2 day^-1 to 45.4 track cm^-2 day^-1 at the bottom face for the plants in which fertilizers were added to soil just before the plantation while it varied from 6.9 track cm^-2 day^-1 to 35.8 track cm^-2 day and 17.9 to 41.3 track cm^-2 day^-1 respectively on the upper and bottom faces for those plants in which fertilizers were added at a later stage. These variations are on higher side as compared to the plants grown without any use of fertilizer has been established.

1 illus, 2 tables, 7 ref

003062   Nain M;Chauhan R P;Kant K;Chakarvarti S K (Physics Dep, Government College, Karnal, Haryana) : Radon exhalation rates from some building construction materials using SSNTDs. Chem envir Res 2006, 15(4), 277-82.

Radon appears mainly by diffusion processes from the point of origin following α- decay of ²²⁶Ra in underground soil and building materials used, in the construction of floors, walls, and ceilings. In dwellings main source of radon are soil or rock underneath building materials and portable water supplies. The major release of radon indoors is from building construction materials used. The radon measurements on the ground can give a clue about the hidden uranium. The exposure of population to high concentrations of radon and its daughters for long period leads to pathological effects like the respiratory functional changes and the occurrence of lung cancer. In the investigations radon exhalation rates from some soil and other building materials like fly ash, cement and sand collected from Panchkula, Amba1a, Yamunanagar, Kurukshetra, Karnal and Panipat districts of Haryana have been estimated. For the measurement of radon concentration in these samples α-sensitive l.R-l15 type n plastic track detectors were used. The mass and the surface exhalation rates of radon emanated from these samples have also been calculated. The aim of study is the possible health risk assessment due to emission of radiation from building construction materials.

1 illus, 1 table, 9 ref

003061   Misra P K (Physics Dep, University of Houston, Houston, TX 77204, USA, Email: prasanta.misra@mail.uh.edu) : Heavy-fermion systems. Indian J Phys 2007, 81(1), 25-31.

Presents a brief review of heavy fermion systems.

31 ref

003060   Mahur A K;Kumar R;Jojo P J;Prasad R (Applied Physics Dep, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh-202 002, Email: ajaymahur345@rediffmail.com) : Indoor radon levels in some dwellings of Thankassery town in Kerala. Chem envir Res 2006, 15(4), 287-91.

Radon monitoring has become a global phenomenon due to its health hazard effects on population. ²²²Rn and its radioactive daughters present in the environment results into the largest contribution to the average effective natural radiation dose received by human beings. Indoor ²²²Rn exposure to the population depends in a complex way on the characteristics of the soil, the building structure, meteorology, ventilation conditions and occupants behaviour. LR-115 type n solid state nuclear track detectors (SSNIDs) have been used for the measurements of indoor radon concentration in 24 rooms of some dwellings situated in Thankassery town along the south west coast of Kerala to carry out the assessment of the variability of expected radiation exposure of the population due to radon and its progeny. The town is situated ear the high background area of Kerala. Radon concentrations are found to vary from 44.3 Bqm^-3 to 373.3 Bqm^-3 with an average of 144.7 ± 61.5 Bqm^-3 whereas the annual effective dose equivalents vary from 1.7 to 142 rnSv/y with an average of 5.5 ± 2.3 mSv/y.

1 illus, 1 table, 10 ref

003059   Mahur A K;Kumar R;Azam A;Jojo P J;Prasad R (Applied Physics Dep, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh-202 002, Email: ajaymahur345@rediffmail.com) : Radon exhalation rate from different types of building construction materials using SSNTDs and estimation of lung cancer risk. Chem envir Res 2006, 15(4), 306-12.

Uranium is a radiotoxic element found in trace quantities in almost all naturally occurring materials like soil, rock and sand etc. Building materials are derived from these materials. Radon, an inert radioactive gas whose predecessor is uranium is emitted from soil beneath the house and from building materials. Building materials are the main source of radon inside the dwellings. Because of low level of radon emanation from these materials, long term measurements are needed. Can technique using LR-115 type II solid state nuclear track detector has been employed for the measurement of radon activity and radon exhalation rate from a number of building materials commonly used for construction in Kerala. Radon activity is found to vary trom 75.0 to 2212.7 Bqm^-3 with an average value of 477.7 Bqm^-3, radon exhalation rate from 44.0 to 1337.7 mBqm^-2h^-l with an average value of 286.3 mBqm^-2h^-1 and effective dose equivalent from 5.2 to 157.7 μSv y^-1 with an average value 33.7 μSv y^-1 for different building construction materials. Radon emanation from granite is found to be maximum while cement brick (hollow) and Kadappa stone give minimum radon emanation. In the case of plastered bricks covered with sealants, radon exhalation is found to increase slightly with acrylic exterior and acrylic emulsion while it decreases with others.

1 illus, 2 tables, 16 ref

003058   Mahajan S;Thakur O P;Chandra Prakash (NO, Solid State Physics Lab, Delhi-110 054) : Effect of sintering temperature on structural and piezoelectric properties of PNN-PZT ceramics. Def Sci J 2007, 57(1), 23-8.

Sintering temperatures affect the structural and piezoelectric properties of PbNi_1/3Nb_2/3-PbZrO₃-PbTiO₃ system considerably; therefore the effect has been studied on mechano-chemically processed powder. This process involves activating mixed oxides of PbO, NiO, Nb₂O₅, ZrO₂ and TiO₂, and in the study, calcination steps at an intermediate temperatures were skipped which are usually required in conventional solid state reaction methods and chemical routes. Single-phase formation was confirmed from XRD patterns which shows rhombohedral structure at higher sintering temperature. Investigations of the microstructure indicate almost linear increase in grain size from 0.98 m to 2.56 m when the sintering temperature was varied from 1050°C to1150C. A high value of planar coupling factor (k_p) = 67 per cent and piezoelectric charge coefficient (d 33 <126> 750 pm/V; (as determined from strain versus electric field curve at low field) were obtained for the ceramic specimens sintered at 1100°C. The maximum strain was observed <126> 0.21 per cent at 40 kV/cm applied field for the sample sintered at 1100°C for 4 h.

^ssc6 illus, 12 ref

003057   Madu C A;Onwuagba B N (Abdus Salam International Centre for Theoretical physics (ICTP), , Trieste, Email: cadamadu@yahoo.com) : Electronic and structural properties of MgS, CaS, SrS and BaS. Indian J Phys 2006, 80(12), 1189-93.

The electronic and structural properties of MgS, CaS, SrS and BaS rocksalt structure are studied with the first principle full potential Linearized Augmented Plane Wave (FP-LAPW) method. The exchange-correlation potential was calculated within the Generalized Gradient Approximation (GGA) using Perdew-Burke-Ernzerh of (PBE-GGA) scheme. The scalar relativistic approach was adopted for the valence states, whereas the core states are treated fully relativistically. Energy band structures, density of states and structural parameters of both compounds are presented and discussed in context with the available theoretical and experimental studies. The results are good and show reasonable agreement with previous results even though sufficient experimental values are not available for more realistic comparison.

8 illus, 3 tables, 35 ref

003056   Kuryan S;Abraham R;Isac J (NO, St Stephen's Coll, Pathanapuram, Kollam, Kerala, Email: jaya_cms@yahoo.co.in ) : Electrical and optical properties of dysprosium barium copper oxalate crystals. Sci Soc 2007, 5(2), 147-52.

Dysprosium barium copper oxalate (DyBaCuOx) crystals were grown using silica gel technique. The dielectric measurements were carried out and the nature of variation of dielectric constant E and dielectric loss D in the frequency range εr 100 Hz to 1 MHz was studied. Photoconductivity studies of DyBaCuOx crystals revealed the negative photo conducting nature.

3 illus, 13 ref

003055   Kurian P A;Vijayan C (Physics Dep, Indian Institute of Technology Madras, Chennai-600 036, Email: ann_pushpa@yahoo.com) : Synthesis, characterisation and nonlinear optical properties of stable PbS nanoclusters. Trans Indian Inst Metals 2006, 59(2), 177-80.

Quantum confinement effects in low-dimensional semiconductors influence the optical properties, rendering them excellent candidates for device applications in Photonics. Presents recent results on the synthesis of stable optical quality films of PbS nanoclusters by a colloidal chemistry method in the size range of few nanometers using lead acetate and sodium sulphide as the precursors. Optical absorption spectra reveal large signature blue shift from the bulk absorption cutoff wavelength. Optical Nonlinearity induced in PbS nanoclusters at low power continuous wave laser excitation is studied by the z-scan method. The origin of the obtained nonlinearity is ana lysed in terms of thermal variation of refractive index.

4 illus, 1 table, 6 ref

003054   Kumar R;Ali S A;Naqvi A H;Awasthi D K;Prasad R (Applied Physics Dep, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh-202 002, Email: drrajesh04@rediffmail.com) : Modification in Makrofol-N polycarbonate by swift heavy ion. Chem envir Res 2006, 15(4), 251-6.

Swift Heavy Ion (SHI) induced modifications in Makrofol-N polycarbonate (PC) irradiated by 100 MeV Si⁸⁺ ion beam have been studied by UV-Visible spectroscopy. The absorbance in UV and Visible range increases with ion fluence and the absorption edge shifts towards the visible region, indicating the carbonization of the material. Films of 40 μm thickness of Makrofol-N (PC) were irradiated with Si⁸⁺ ion of energy 100 MeV to the fluences of 10¹⁰, 10¹¹, and 10¹² ions/cm² at Pelletron accelerator at Inter-University Accelerator Centre, New Delhi. Optical modifications were characterized by UV-VIS Spectroscopy. The cluster size varied in a range of 4 to 6 carbon atoms per cluster. Energy band gap has been found to decrease with transferred energy density of the ion beams. The optical band gap (Eg) values, computed from the absorption edge in the 200-800 region using Tauc formula varied from 4.36 eV to 2.76 eV in Sⁱ⁸⁺ irradiated samples.

2 illus, 1 table, 20 ref

003053   Kumar A;Sharma D K;Singh S (Physics Dep, DAV College, Amritsar, Punjab, Email: ajay782@rediffmail.com) : Radium and radon exhalation rate in some soil and rock samples using solid state nuclear track detectors. Chem envir Res 2006, 15(4), 329-33.

The `track etch' technique using solid state nuclear track detectors have been employed for measuring the radium content and radon exhalation rate in some soil and rock samples collected from some villages of Una district, Himachal Pradesh, India. The values of radium and radon exhalation rate in soil as well as in rock samples is maximum in Nalute village and minimum in village Rajli Uparli. The values are generally found to be more in soil compared with rock samples. A strong correlation (correlation coefficient = 0.99) has been observed between radium and radon exhalation rate.

2 illus, 2 tables, 12 ref

003052   Kolekar R V;Sharma D N (Radiation Safety Systems Div, Bhabha Atomic Research Centre, Mumbai-400 085) : Mass distribution of fission fragments using SSNTDs based image analysis system. Chem envir Res 2006, 15(4), 334-7.

Lexan polycarbonate track detector was used to obtain mass distribution of fission fragments from Cf-252 planchette source. Normally, if the fission fragments are incident perpendicular to the lexan surface, the diameter of heavy fragment is greater than that of lighter fragment. In practical problems fission fragments are incident on the detector at all angles. So, in the present experiment, lexan detector was exposed to Cf-252 planchette source in 2π geometry. Fission fragments were incident on the detector with various angles. So the projected fission track length for fission fragment of same energy is different because of different angle of incidence. Image analysis software was used to measure the projected track length. But the problem is that for fission fragment having greater angle of incidence the entire track length is not focused on the surface. So reduced track length is measured. This problem is solved by taking two images, one at the surface and one at the tip of track and then overlapping both the images using image analysis software. The projected track length and the depth of the track were used to get the angle of incidence. Fission track lengths were measured for same angle of incidence. In all 500 track lengths were measured and plot for mass destitution for fission fragment was obtained.

3 illus, 1 table, 2 ref

003051   Kolekar R V;Kumar R;Dravid H K;Sharma D N (Radiation Safety Systems Div, Reactor Physics and Design Div, Bhabha Atomic Research Centre, Mumbai-400 085) : Applications of solid state nuclear track detectors in the shielding experiments of advanced heavy water reactor. Chem envir Res 2006, 15(4), 354-8.

Advanced heavy water reactor (AHWR) project taken up in BARC, for large scale commercial utilization of thorium fuel cycle. AHWR end shield consists of large number of streaming paths of various shapes and sizes. The thickness of the end shield is mainly governed by the streaming through these paths. As the calculation of radiation streaming is difficult, a large number of radiation streaming experiments were carried in the shielding comer of Apsara reactor in BARC. Measured data were compared with the calculations using Monte carlo neutron photon transport code. Solid state nuclear track detectors were used to study the neutron attenuation through various shield models. It. was observed that Npª-237 in combination with Lexan detector were particularly useful in providing the reaction rate data for intermediate energy neutrons of 0.6 MeV. Neutron attenuation through solid concrete model, ventilation duct model and end shield model with 3 mm annular duct of air were studied.

3 illus, 1 table, 4 ref

003050   Khesali A R;Bagherian M A (Physics Dep, Faculty of Basic Sci, Univ of Mazandaran, P.O. Box 47416-1467, Babolsar, Iran) : Nonlinear thermal instability in ISM: typical net cooling functions. Bull Astr Soc India 2007, 35(1), 1-13.

The nonlinear evolution of thermally unstable disturbances in plasma have been investigated within the framework of one-dimensional fluid equations. The processes of heating and radiative cooling (cooling function) of the optically thin plasma are taken into account. A new statistical approach is presented to study the thermal instability to the interstellar medium ISM of an optically thin unmagnetized plasma. This approach makes possible to simplify the set of equations describing the instability, and using Lagrangian coordinates, to investigate the nonlinear dynamics of the instability analytically. The equations are solved both analytically and numerically by successive approximations assuming a thermal conduction coefficient T and cooling function coefficient of type T^a - T^b. Author discuss the nonlinear development of the isobaric mode of thermal instability in the atomic molecular clouds of ISM.

4 illus, 13 ref

003049   Kar S;Vishal Dev;Ashok;Chaudhuri S (Materials Sciencde Dep, Indian Association for the Cultivation of Science, Kolkata-700 032) : Mn-doped Zn₂SiO₄ thin films prepared by a simple sol-gel route: photolumines cence properties. Indian J Phys 2006, 80(12), 1171-4.

Mn-doped Zn₂SiO₄ thin films were prepared on Si substrates by a simple sol-gel route. The films were prepared by dip-coating techniquc followed by annealing Ireatment in Ar atmosphere. The crystal structure and phase of the products were identified by X-ray diffraction studies. The micro-structural sludies by scanning electron microscopy revealed well-defined granular nature of the films. The films exhibited a characteristic green emission at <126> 521 nm at room temperature attributed to the ⁴T₁, (⁴G) to ⁶A₁(⁶S) transition. 

3 illus, 22 ref

003048   Kar S;Sharma R G (NO, Inter University Accelerator Center, New Delhi-110 067) : Cryogenic temperature sensors. Def Sci J 2007, 57(3), 195-208.

Describes the different cryogenic temperature sensors used at cryogenic temperatures down to 1 K. The characteristics of these temperature sensors have been discussed in detail with their operating range, sensitivity, and accuracy. Other properties like interchangeability, effect of thermal cycling, effect of ionizing radiation (neutron or gamma ray), effect of magnetic field has also been described. It is extremely important to choose the right temperature sensor for right kind of application in a specific operating environment. Gives an overview of some of the most widely used cryogenic temperature sensors.

^iia25 illus, 22 ref

003047   Joshi M;Manju Kumar L;Gajjar P N;Thakore B Y; Jani A R (Physics Dep, Sarder Patel University, Vallabh Vidyanagar-388 120, Email: mjjoshi2004@yahoo.com) : Theoretical investigation of shear viscosity of some less simple liquid metals. Indian J Phys 2007, 81(1), 137-41.

Theoretical investigation of the temperature dependent Shear Viscosities are reported for some less simple liquid metals of group II-VI. Well established model potential with recent local field correction functions of Ichimaru-Utsumi is used to derive the proper interionic pair interactions. Charged Hard Sphere reference system is employed to compute the structural data for these less simple liquid metals. Results are in good agreement when compared with the available experimental and other theoretical findings. This reveals qualitative applicability of the model potential to define atomic transport properties.

1 illus, 2 tables, 16 ref

003046   Jaseentha O P;Menon C S (School of Pure and Applied Physics, Mahatma Gandhi Univ, Kottayam-686 560, Email: opjessy@yahoo.co.in) : Optical characterization of zinc hexadecafluoro phthalocyanine thin films. Sci Soc 2007, 5(2), 139-46.

Metal phthalocyanines are hole transport materials whereas fluorinated metal phthalocyanines are electron transport materials. Using thermal evaporation technique thin films of zinc hexadecafluoro phthalocyanine (F₁₆ZnPc) are deposited on to pre cleaned glass substrates. Spectroscopic measurements are used for the calculation of optical parameters. Heat-treated samples are used to study the variation of optical band gap. Results showed that these films are suitable for the fabrication of Fast Response Organic Photo detectors. Light emitting diodes, ambipolar transistors, and molecular electronic components.

8 illus, 14 ref

003045   Jana D;Chen L C;Chen C W;Chen K H (Physics Dep, University of Calcutta, 92 A P C Road, Kolkata-700 009) : Ab-initio study of optical conductivity of B_xC_y nano-composite system. Indian J Phys 2007, 81(1), 41-5.

Computes the imaginary part of the dielectric constant ε (q → O, ε) of Single Wall Carbon Nanotubes (SWCNTs) alloyed with Boron (B) through fixed C-C bond length ab-initio Density Functional Theory (OFT). It is observed that the dielectric constants (both real as well as imaginary) essentially depend on B-doping concentration as well as the direction of polarization. In particular, demonstrates that the maximum value of the optical conductivity of this composite system depends strongly on the B-concentration in a non-linear way with a unique minimum at a particular critical concentration. This study may be of importance in discussing the nature of collective excitations in B-alloyed SWCNT system.

3 illus, 1 table, 17 ref

003044   Islam S S;Shah K A;Mavi H S;Shaukla A K;Rath S;Harsh (Applied Sciences and Humanities Dep, Faculty of Engineering and Techno, Jamia Millia Islamia (Central Univ), New Delhi-110 025, Email: safiul_el@rediffmail.com) : Raman study on single-walled carbon nanotubes with different laser excitation energies. Bull Mater Sci 2007, 30(3), 295-9.

Industrial use of carbon nanotubes is increasing day by day; therefore, it is very important to identify the nature of carbon nanotubes in a bundle. Uses the Raman spectroscopic analysis on vertically aligned single-walled carbon nanotubes (SWCNTs) grown by the chemical vapour deposition (CVD) technique. The grown sample is excited with two laser excitation wavelengths, 633 nm from He-Ne laser and 514.5 nm from Ar⁺ laser. Raman spectrum in the backscattering geometry provides the characteristic spectra of SWCNTs with its radial breathing mode (RBM), defect-induced disorder mode (D band), and high-energy modes (G and M bands). The Raman signal positions of the spectra in RBM, G and M bands confirm the grown sample to be of semiconducting type in nature.

3 illus, 32 ref

003043   Goraya P S (Phys Dep, Punjabi Univ, Patiala-147 002, Email: goray@iucaa.emet.in) : Variable spectral energy distribution of γ Cassiopeiae in the optical region. Bull Astr Soc India 2007, 35(1), 23-9.

Spectrophotometrically measured continuum energy distribution of γ Cassiopeiae are presented during six nights in the wavelength range of λ λ3200-8000 Angstrom. The observations are compared with the theoretical models and are used to derive the values of effective temperature, gravity and to explore the behaviour of the continuum. It is found that γ Cassiopeiae exhibited moderate to strong near-ultraviolet and near-infrared excess radiation over the underlying photospheric emission, with variable intensity on a time-scale of months to years. The amount of extra emission has been measured in magnitude units. The discovery of two steps in Balmer jumps during one night is being reported for the first time in this star. The second step of Balmer jump is found strongly in emission and exhibited short time-scale variations. The measures of Balmer jumps and λ₁ (Angstrom) parameters are also made for this star.

5 illus, 2 tables, 83 ref

003042   Ghosh S;Kanjilal D;Som T (NO, Institute of Physics, Sachivalaya Marg, Bhubaneswar-751 005, Email: tsom@iopb.res.in ) : Low energy ion irradiation induced modifications in Co/Pt bi-layers. Indian J Phys 2007, 81(1), 83-7.

Reports on 150 keV Ar and 250 keV Kr ion-irradiation induced modification of Pt(8 nm)/Co(85 nm)/Si bilayers. X-Ray diffraction, Rutherford backscattering spectrometry and magneto optical Kerr effect measurements have been performed to study the changes in structural and magnetic properties of the technologically important Co/Pt bi-layer system due to low energy ion irradiation. The combined result from XRD and RBS measurements strongly indicate that ion beam induced mixing takes place across the Co/Pt interface leading to the formation of Co-Pt phase and simultaneous sputtering of the Pt atoms from the top most layer. Magneto optical Kerr effect data reveal the corresponding changes in the magnetic properties due to the formation of Co-Pt alloy.

5 illus, 13 ref

003041   Ghosh P K;Ahmed S F;Maiti U N;Chattopadhyay K K (Thin Film and Nanoscience Lab, Physics Dep, Jadavpur University, Kolkata-700 032, Email: kalyan_chattopadhyay@yahoo.com) : Structural and optical properties of ZnS nanostructured films synthesized via RF-magnetron sputtering technique. Indian J Phys 2007, 81(1), 69-73.

Nanostructured ZnS thin films have been synthesized by radio frequency magnetron sputtering technique. X-ray diffraction and selected area electron diffraction studies confirmed the formation of nanocrystalline cubic phase of ZnS in the films. The particle size calculated from the XRD patterns of the thin films was found in the range 2.06-4.86 nm. TEM micrographs of the thin films revealed the manifestation of ZnS nanoparticles with sizes lying in the range 3.00-5.83 nm. UV-Vis-NIR spectrophotometric measurements showed that the films are highly transparent (<126>90%) in the wavelength range 500-2600 nm. The absorption edge showed a blue shill. The direct allowed bandgaps was found in the range 3.89-4.44 eV. The room temperature photoluminescence spectra of the films showed two peaks centered around 315 nm and 450 nm. Assigned the first peak due to bandgap transitions while the latter due to sulfur vacancy in the films. The composition analysis by energy dispersive X-rays also supported the existence of sulfur deficiency in the films. The thicknesses of the films were in the range 260-350 nm depending on the deposition time.

4 illus, 2 tables, 8 ref

003040   Gajjar P N;Mishra S R;Jani A R (Physics Dep, University School of Sciences, Gujarat University, Ahmedabad-380 009, Email: pngajjar@rediffmail.com) : Electrical resistivity of liquid K-Rb-Cs alloys. Indian J Phys 2007, 81(1), 125-9.

Model potential consisting of varying cancellation of attractive and repulsive potentials within the core is applied for the first time to study the electrical resistivity of liquid K-Rb-Cs alloys. The influence of exchange and correlation effects are also studied by including local-field correlation functions due to Hartree, Taylor, Ichimaru-Utsumi, Farid et al, and Sarkar et al. The results for electrical resistivity of pure metallic components (K, Rb and Cs), liquid binaries (K-Rb, Rb-Cs and K-Cs) and liquid ternary (K-Rb-Cs) favours the formulation of new model potential. The comparison of present results with those obtained due to self-consistent energy independent model potential and experimental findings also confirm the validity of this model in the study of ternary alloys.

2 illus, 1 table, 19 ref

003039   Dole B N;Shah S S (J.E.S. Research Centre, P.G. Physics Dep, J.E.S. College, Jalna-431 203) : Some physical properties of Pr doped Y-123 high T_c superconductors. Indian J Cryogenics 2005, 30(1), 30-3.

Iinvestigated Y_1-xPr_xBa₂Cu₃O₇δ high purity system with compositions x = 0.0, 0.2, 0.3 and 0.4. The samples of the system were prepared by nitrate evaporation route. The substitution of Pr in Y-123 compounds reduces the critical temperature (T_c) monotonically with enhancing the Pr content, but other rare earth elements do not decrease the T_c drastically. Pr is an exception for this. This anomalous behavior of Pr attracts a lot of attention of scientists,. theorists, technologists and researchers. There is controversy about the valency of Pr and it is exactly not known whether it is in 3+ valence state or 4+ valence state or mixed valence state. X - ray diffraction data for the system were obtained and were close to the reports in the literature, The characterization study of the system was done by resistivity measurements. Theoretical T_c experimental T_c and BCS T_c values were calculated and it is found that there is good matching amongst them. Determined the energy gap parameter (D₀) theoretically, experimentally and BCS energy gap parameter from obtained T_c values and it is observed that there is good agreement amongst them. The electron phonon interaction parameter (g) is calculated for the system. It is seen that g goes on decreasing as Pr content increases. The reduction in puckering and decrease in g with increasing Pr content may result in suppression of T_c in Y-123 system.

3 illus, 14 ref

003038   Dhairyawan M P;Nair S (Personnel Monitoring Sect, Radiological Physics and Advisory Div, Bhabha Atomic Research Centre, Anushaktinagar, Mumbai-400 094, Email: mpdhairyawan@yahoo.co.in) : Fast neutron personnel monitoring in India. Chem envir Res 2006, 15(4), 232-7.

Personnel Monitoring Section, BARC conducts countrywide fast neutron personnel monitoring using CR-39 solid state nuclear track detector. About 1650 personnel working in a wide range of situations are being monitored presently for fast neutrons. Nearly 50% of the personnel monitored are working with isotopic neutron sources e.g. ²⁴¹Am-Be (up to 740 Gbq source strength) in industry and the remaining are connected with nuclear fuel cycle. Describes the experience with this personnel neutron monitor and presents the analysis of the neutron equivalent doses received by the personnel working in research and associated with accelerators, during last 15 years and its contribution as compared to total equivalent dose.

3 tables, 6 ref

003037   Desai R;Mehta R V;Upadhyay R V;Gupta A; Praneet A;Rao K V (Physics Dep, Bhavnagar Univ, Bhavnagar-364 002, Email: rvu@bhavuni.edu) : Bulk magnetic properties of CdFe₂O₄ in nano-regime. Bull Mater Sci 2007, 30(3), 197-203.

Cadmium ferrite particles have been synthesized using co-precipitation technique followed by a low temperature (600°C) annealing in a time scale much shorter than reported in literature. Incorporation of sodium chloride during annealing helps to form a single phase spinel structure with a final particle size of around 50 nm. Even at such a short length scale we observe the overall magnetic properties to be similar to those of the bulk. The observed magnetic properties can be explained on the basis of an anti-ferromagnetic core with a shell containing 'ferromagnetic-like', but canted spin structure.

7 illus, 2 tables, 17 ref

003036   Deka P C;Sarkar S;Goswami T D;Sarma B K (Physics Dep, Rangia College, Rangia-781 354, Email: pdekarc@rediffmail.com) : Indoor radon, thoron and their progeny concentration levels in the surrounding areas of Mangaldoi, Assam. Chem envir Res 2006, 15(4), 292-305.

Measurements of concentration of radon. thoron and their decay products in various indoor environment covering four seasons of a year were carried out using the passive time-integrated method by employing LR-15 type n detectors in plastic twin-chamber dosimeter cups. The estimated indoor radon levels for well ventilated houses varied from a minimum value of 25.2 Bq.m^-3 to a maximum of 80.1 Bq.m^-3 with an annual geometric mean of 46.9 Bq.m^-3 and that for poorly ventilated houses varied from a minimum value of 46.8 Bq.m^-3 to a maximum of 146.8 Bq.m^-3 with the annual geometric mean of 82.2 Bq.m^-3. The thoron levels in well ventilated houses were also varied from a minimum value of 4.9 Bq.m^-3 to a maximum of 21.5 Bq.m^-3 with an annual geometric mean of 10.5 Bq.m^-3 and that for poorly ventilated houses varied from a minimum of 6.3 Bq.m^-3 to a maximum value of 29.2 Bq.m^-3 with the annual geometric mean of 14.1 Bq.m^-3. Thus it is seen that both radon and thoron levels are higher in poorly ventilated houses than in well-ventilated houses. The ranges of radon and thoron progeny levels for well ventilated houses were 0.10 mWL to 0.58 mWL with an annual geometric mean of 0.21 mWL and 0.01 mWL to 0.06 mWL with an annual geometric mean of 0.03 mWL respectively. Similar variation was also observed in poorly ventilated houses.

12 illus, 7 tables, 8 ref

003035   Das U;Mohanta D;Singh F;Tripathi A;Avasthi D K;Choudhury A (Physics Dep, Tezpur University, Napaam, Assam-784 028) : Transition metal doped ZnS nanopartiacle systems and their response to swift heavy ion irradiation. Indian J Phys 2007, 81(1), 155-9.

Transition metal (Cr) doped ZnS nanoparticles were fabricated by adopting a solution growth-chemical route. They were irradiated by 150-MeV titanium ion beams using tandem pelletron accelerator available at IUAC, New Delhi. Irradiation led manifestations in luminescence patterns and morphology has been discussed in analogy with modification in magnetic domains. The study would find promising application in magnetic sensors and spintronics devices.

3 illus, 1 table, 20 ref

003034   Choudhury A K;Chatterjee A K;Nandi A (Centre for Space Physics, , Malda Branch, Atul Market, Malda-732 101) : Different types of class transitions of GRS 1915+105 using IXAE data. Bull Astr Soc India 2007, 35(1), 41-2.

The microquasar GRS 1915+105 exhibits at least 13 distinct classes of light curves. Author observed different types of class transitions of light curves of GRS 1915+105 by analyzing the data obtained from the Indian X-ray Astronomy Experiment (IXAE) instrument aboard the Indian satellite IRS-P3 and with data from the Rossi X-ray Timing Explorer (RXTE) archives. Authors show seven different types of class transitions in the data obtained from IXAE. It is also observed that the QPO frequencies are changing during the transitions. Assuming that the transitions are caused by variations in the accretion rates, implies that a significant fraction of the matter must be nearly freely falling in order to have such transitions.

7 illus, 1 table, 35 ref

003033   Choudhary S N;Prasad K;Kumar A;Choudhary R N P (University Physics Dep, T M Bhagalpur University, Bhagalpur-812 007) : Vogel-Fulcher like dielectric response in Pb[Mg, Zn)_1/3Nb_2/3Nb_2/3]O₃ ceramic. Indian J Phys 2007, 81(1), 109-16.

Polycrystalline Pb[(Mg_2/3Zn_1/3) _1/3Nb_2/3]O₃ having tetragonal perovskite type structure was prepared by a high temperature solid state reaction method. Dielectric constant and loss tangent were measured over a frequency range 1 kHz to 1 MHz in the temperature region 32°C to 225°C. Dielectric studies show the relaxor behaviour with diffuse phase transition. The frequency dependence of the temperature of the permittivity maximum (T_m) has been modeled using Vogel-Fulcher relation. The dielectric relaxation in Pb[(Mg_2/3Zn_1/3)_1/3Nb_2/3]O₃ is found analogous to the magnetic relaxation in spin-glass system. Cole-Cole analysis indicated that the relaxation is of polydispersive non-Debye type and the relaxation frequency shifts to higher frequencies with the increase in temperature.

4 illus, 1 table, 35 ref

003032   Chauhan R P;Upadhyay S B;Narula A K; Chakravarti S K (Physics Dep, Indira Gandhi National College, Ladwa-136 132) : Effect of grain size on radon diffusion through some building construction materials. Chem envir Res 2006, 15(4), 223-7.

The diffusion of radon in dwellings is a process determined by the radon concentration gradient across the building material structure between the radon source and the surrounding air, and can be a significant contributor to indoor radon inflow. Radon can originate from the deeply buried deposit beneath homes and can migrate to the surface of earth. Radon appears mainly by diffusion processes from the point of origin following α- decay of ²²⁶Ra in underground soil and building materials used, in the construction of floors, walls, and ceilings. In the study radon diffusion through some building materials viz.; soil, fly ash, sand, cement etc. has been carried out using LR-115 typen solid-state nuclear track detectors (SSN1Ds). The radon diffusion coefficients and diffusion lengths through these building construction materials have been calculated. Out of building materials studied during investigations, cement is found to be the least permeable to radon flow with diffusion coefficient 1.12 x 10^-6 m² s^-1 and diffusion length from 0.73 m. The effect of grain size on radon diffusion through Soil as building construction material has also been studied. The radon diffusion through soil is decreased with decrease in grain size.

2 tables, 7 ref

003031   Chandra S;Sharma R;Annapoorni S;Sonkawade R G;Rana J M S;Ramola R C (Physics Dep, H.N.B. Garhwal University, Badshahi Thaul Campus, Tehri Garhwal-249 199) : Change in electrical properties of polyaniline pallet, irradiated by lithium beam. Chem envir Res 2006, 15(4), 211-14.

Polyaniline pallet was synthesized by chemical route method in which 1M Aniline monomer was added to 1M HCl and Ammonium Persulphate used as oxidant. After completing the reaction at ice temperature, the solution was extracted in Soxhlet assembly to remove the oligomers. The pallet was then prepared from the dried solution using a pellet-making machine of 13 mm in diameter at a hydraulic pressure of 1600 K. The dc conductivity was measured at room temperature by four-probe technique in order to eliminate contact resistance using Kettley Meter. This pallet was irradiated by lithium beam of energy 50 MeV and a fluence of lEl2 at 9 pnA Faraday cup current. In order to find a significant change in the electrical property of polyaniline pallet, the de conductivity was measured after the irradiation. The conductivity of polyaniline pallet was found to increase after the irradiation. This increase may be due the formation of polarons and bipolarons, which ultimately increase the mobility of the electron in the material. The synthesis and effect of interaction of ion beam in polyaniline are discussed in details. To determine the structure of the pallet X-Ray diffraction was done for the pristine and the indicated pallets. It was found that crystallinity is increasing after the irradiation.

2 illus, 5 ref

003030   Calisir E D;Erkoc S;Yildirim H;Kara A;Rahman T S;Selvi M;Erkoc F (Physic Dep, Middle East Technical Univ, 06531 Ankara, Turkey, Email: rkoc@erkoc.physics.metu.edu.tr) : Theoretical comparative study of the structure, dynamics and electronic properties of two allyl molecules: S-allyl cysteine (SAC) and S-allyl mercaptocysteine (SAMC). Int J pure appl Chem 2006, 1(1), 45-55.

The structural, dynamic and electronic properties of two allyl molecules (S-allyl cysteine and S- allyl mercaptocysteine) have been investigated theoretically by performing semi-empirical molecular orbital (AMI and PM3), ab initio (RHF) and density functional theory calculations. The geometry of the molecules have been optimized, the vibrational spectra and the electronic properties of the molecules have been calculated in their ground states in gas phase. For each of the two molecules, author found that the optimized geometries resulting from calculations based on the three levels of accuracy, to be very similar. However, found that an accurate description of the vibrational properties of these molecules necessitates calculations at the ab initio level. Author also found electronic structures of the molecules to be satisfactory when performed at the DFT level.

8 illus, 5 tables, 28 ref

003029   Bordoloi A K;Mahanta D;Dolui S K;Choudhury A (Physics Dep, Tezpur University, Tezpur, Assam) : Optical and electrical properties of chemically grown ZnS quantum dots. Indian J Phys 2007, 81(1), 89-93.

Sucessful preparation of highly nano dispersive and nano crystalline ZnS semiconductor quantum dots by chemical method in polyvinyl alcohol (PVA) has been reported. The optical absorption studies were done for size quantization. Photoluminescence was carried out to study the presence of surface states. The sizes of the particle were estimated from XRD and TEM studies. Further the current-voltage measurement confirmed the presence of surface states.

7 illus, 1 table, 12 ref