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[en] Variable Energy Cyclotron Centre (VECC) at Kolkata has developed a compact room temperature Electron Cyclotron Resonance Ion Source for production of various heavy ion beams viz. N⁵⁺, 0⁷⁺, Ne⁷⁺ etc. The ECR ion source along with its axial injection system consists of several subsystems like vacuum, power supply, low conductivity water system and so on. As a part of the computerized control of the total operation of the ECR ion source, an on-off control of the vacuum system has been developed. (author)

[en] The idea of representing the character of a charged particle beam by means of its emittance ellipses, is essentially a mathematical one. For quick understanding of the beam character in a more user-friendly way, unit beam cells with particles having a uniform nature, have been pictured by suitably shaped 3-D solids. The X and Y direction momenta at particular cell areas of the particle beam combine together to give a proportionate orientation to the solid in the pseudo 3-D world of the graphic screen, creating a physical picture of the particle beam. This is expected to facilitate the comprehension of total characteristics of a beam in cases of online control of transport lines and their designs, when interfaced with various ray-tracing programs. The implementation is done in an IBM-PC environment. (author)

[en] Of the various types of ion sources, Electron Cyclotron Resonance (ECR) ion source is the most frequently used heavy ion source for cyclotrons. The objective of the present development is to provide remote monitoring and control of the operation of a set of power supplies through a user-friendly human-computer interface (HCI). A brief description of the system is presented in this paper

[en] The polycrystalline Copper Indium Selenide (CuInSe/sub 2/) was grown by direct combination of the stoichiometric quantities of Cu, In and Se and also by the combination of the binary components like Cu/sub 2/Se and In/sub 2/Se/sub 2/, which were separately synthesized. Thin films were obtained on glass and alumina substrates by vacuum evaporation of bulk CuInSe/sub 2/ using single source and double source evaporation systems. The bulk material as well as the thin films were characterized electrically for resistivity, carrier concentration and mobility and optically for band gap and other impurity energy levels. Effect of annealing on the properties of thin film was also studied

[en] The present work deals with the study of the effect of temperature on the Raman spectroscopy and electrical properties of the silicon nanowires. The nanowires are fabricated through silver assisted electrochemical etching process. Prior to these studies, the fabricated nanowires are characterized through field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), and X-ray diffraction (XRD) measurements. FESEM reveals the vertical alignment of the nanowires. FETEM indicates the materials to be highly crystalline, which is also complemented by the XRD result. Raman peak is blue-shifted with a decrease of temperature suggesting lattice disturbance at low temperature. Temperature-dependent current-voltage (I-V) measurements are fitted with Cheung's model and the characteristic parameters viz. ideality factor (n), barrier height (ϕ_b), and series resistance (R_s) are estimated from the fitted plots. At lower temperatures, the value of n highly deviates from the ideal value of unity and is 23.42 at 110 K. The materials are observed to obey space charge limited conduction (SCLC) to trap charge limit current (TCLC) with increasing bias at lower temperatures. (author)

[en] Schottky junctions are constructed by depositing PANI-ZnS and PANI-CdS nanocomposite thin films on ITO electrodes. Current-voltage (I-V) measurements of these systems are performed as a function of temperature in the range of 313-363 K. These junctions show Schottky diode nature. Various parameters, such as saturation current (I₀), ideality factor (n), barrier height (∅₀) and series resistance (R_S), are calculated from diode characteristics relations. These parameters show strong temperature dependence. The values of I₀ and ∅ increase with increasing temperature, whereas the values of n and R_S show decreasing trend. A Richardson plot of the data shows nonlinear behaviour with Richardson constant ∼76 and 45 A cm^-2 K^-2 for PANI-ZnS and PANI-CdS nanocomposite thin films, respectively. (author)

[en] ZnS nanocrystals are grown into the polyvinyl alcohol matrix by chemical bath deposition. XRD result of the composite film shows wurtzite structure with peaks at 2θ values of 28.5°, 47.58° and 56.39° for (002), (110) and (112) planes respectively. SEM and TEM micrographs of the films reveal formation of spherical ZnS nanoparticles. Nanostructured thin film prepared under optimum growth conditions shows bandgap value of 3.65 eV, as observed from UV–Visible transmission spectrum. Room temperature photoluminescence spectrum shows peak at 396 nm. I–V shows symmetric nonlinear behavior under illumination. Electrical conductivity shows semiconduction nature. (author)

[en] Thin films of different metals M (M=Ti, Zr, Hf, Nb, Fe, and Ni) of thickness around 10 nm are deposited on Si(100) substrates and a ∼30nm Co film is deposited on these metal films using the magnetron sputtering method. Cross-sectional transmission electron microscopy (XTEM) shows the presence of a ∼2nm buried ultrathin amorphous interlayer at the interface between the Co layer and the M layers (M=Ti, Zr, Hf, and Nb). X-ray reflectivity is used to determine the electron density of this buried ultrathin amorphous interlayer. X-ray diffraction (XRD) is used to determine the crystalline quality of the deposited Co film on these various metal film substrates. The XRD peaks of Co(111) and Co(222) are observed when Ti, Zr, Hf, and Nb are used as substrates. Pole figure measurements confirm that the Co film is highly textured on such metallic substrates. On the other hand no characteristic XRD peaks of cobalt are observed when Ni and Fe are used as the substrate, however, XTEM shows the presence of the Co film on those substrates. Theoretically, the heat of mixing (-ΔH) has been calculated for Co - M systems. The local temperature rise is estimated using the average heat capacity and the calculated heat of mixing of the amorphous interface compound (Co₃M). The local temperature rise due to the amorphous phase formation and hence better mobility of the further deposited metal atoms is the cause of highly textured Co thin films on such metal substrates. [copyright] 2001 American Institute of Physics

[en] Polypyrrole (PPy) is embedded in polyvinyl alcohol (PVA) matrix to give a homogeneous composite solution by dispersing PPy in PVA solution. Scanning electron microscopic (SEM) study on the film prepared from the composite solution shows uniform distribution of nearly spherical shaped PPy grains of average diameter of 20 nm. The X-ray diffraction (XRD), UV–visible and Fourier transform infra-red (FTIR) spectroscopic characterizations of the composite film are carried out for structural and optical properties. The enhanced thermal stability of the PPy–PVA composite film is confirmed by thermogravimetric analysis (TGA). XRD shows signature of amorphous nature for PVA along with some crystallinity arising for PPy. UV–visible absorption spectrum shows two absorption peaks for π–π* and polaronic transition; FTIR spectrum suggests cross linking between PPy and PVA. Studies on sensing of the PPy–PVA composite film for ethanol, ammonia, toluene, chloroform and acetone vapors at room temperature (300 K) are done for comparison. The composite film shows best response among all these vapors towards ethanol requiring smallest response time.