Synthesis of TiN/a-Si3N4 thin film by using a Mather type dense plasma focus system

A 2.3 kJ Mather type pulsed plasma focus device was used for the synthesis of a TiN/a-Si3N4 thin film at room temperature. The film was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The XRD pattern confirms the growth of polycrystalline TiN thin film. The XPS results indicate that the synthesized film is non-stoichiometric and contains titanium nitride, silicon nitride, and a phase of silicon oxy-nitride. The SEM and AFM results reveal that the surface of the synthesized film is quite smooth with 0.59 nm roughness (root-mean-square).     

Regenerative soot as a source of broad band VUV light

Certain important and pertinent questions have been raised by E. Träbert in his comment on the paper [Eur. Phys. J. D 22, 189 (2003)] by one of us. We provide explanations as well as new and recent data using a calibrated monochromator on the existence of the main intercombination multiplet 233 nm which is the bone of contention. It is shown that there is no conflict with the established atomic physics in the regenerative sooting discharges; only the interpretations are at variance with those of the comment.Received: 30 July 2003, Published online: 30 September 2003PACS: 32.70.Fw Absolute and relative intensities - 34.50.Dy Interactions of atoms and molecules with surfaces; photon and electron emission; neutralization of ions - 34.80.Dp Atomic excitation and ionization by electron impact     

Determination of uranium contents in rock samples from Kakul phosphate deposit, Abbotabad (Pakistan), using fission-track technique

Some times high uranium contents are present in the phosphate rocks used for the manufacturing of fertilizer. In view of the harmful effects on human health due to the processing and use of such fertilizers in agriculture, it is important to analyse phosphate rocks for uranium content determination. Ten representative rock samples from Kakul phosphate deposit exposed near Abbotabad, Pakistan which are used for the manufacturing of fertilizers were studied for uranium content determination with the help of fission track and neutron activation analysis techniques. Each sample was split into three parts. The first and second parts (solid slabs and pellets) were subjected to fission track analysis, while the third part was analysed using neutron activation analysis technique for comparison. On the average a uranium content of 37 ppm was found in the phosphate rocks. The results of uranium content determinations with the help of fission track and neutron activation analysis techniques show a remarked resemblance up to ±0.1%. This indicates that the fission track analysis technique of uranium content determination is a reliable method inspite of its simplicity. The uranium content in the Kakul deposits is within the permissible limit allowed for the mining and processing of the phosphate rocks for the manufacturing of fertilizers.     

Fermi surface reconstruction in the CDW state of CeTe3 observed by photoemission

CeTe3 is a layered compound where an incommensurate charge density wave (CDW) opens a large gap ( approximately 400 meV) in optimally nested regions of the Fermi surface (FS), whereas other sections with poorer nesting remain ungapped. Through angle-resolved photoemission, we identify bands backfolded according to the CDW periodicity. They define FS pockets formed by the intersection of the original FS and its CDW replica. Such pockets illustrate very directly the role of nesting in the CDW formation but they could not be detected so far in a CDW system. We address the reasons for the weak intensity of the folded bands, by comparing different foldings coexisting in CeTe3.     

Effect of displacement on resistance and capacitance of polyaniline film

This paper investigates the properties of displacement sensors based on polyaniline (PANI) films. About 1 wt% of PANI micropowder is mixed and stirred in a solution of 90 wt% water and 10 wt% alcohol at room temperature. The films of PANI are deposited from solution by drop-casting on Ag electrodes,which are preliminary deposited on glass substrates. The thicknesses of the PANI films are in the range of 20 μm-80 μm. A displacement sensor with polyaniline film as an active material is designed and fabricated. The investigations showed that,on average,the AC resistance of the sensor decreases by 2 times and the capacitance accordingly increases by 1.6 times as the displacement changes in the range of 0 mm-0.5 mm. The polyaniline is the only active material of the displacement sensor. The resistance and capacitance of the PANI changes under the pressure of spring and elastic rubber,and this pressure is created by the downward movement of the micrometer.     

Scattering from a PEC strip buried in non-integer dimensional planar grounded dielectric slab by using Kobayashi potential method

Solution for electromagnetic scattering from a perfect electric conducting strip buried in a planar grounded dielectric slab is determined by using the Kobayashi Potential Method. It is assumed that the dimension of mediums, above and within the slab, is non-integer in the direction normal to interface of the slab. The scattering problem is divided into two parts. In the first part, fields in the absence of strip are determined for plane wave excitation. In the second part, presence of the strip is taken into account. It has been assumed that spacings between the strip and interfaces of the slab are comparatively very larger than the wavelength of monochromatic operating frequency. Due to this assumption, scattered field after reflection from the interfaces has no interaction with the strip. In order to gains more insight, several special cases of the geometry are treated. Using saddle point method, far-zone scattered field for region above the grounded slab is also determined.     

Effect of Viscosity on the Spin Exchange of TCNE and TEMPO Radicals with Iron(III) Acetylacetonate

The spin exchange of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and the radical anion of tetracyanoethene (TCNE), with iron acetylacetonate, Fe(acac)₃, was investigated as a function of solvent viscosity and temperature by X-band EPR spectroscopy. Acetone, methanol, ethanol, 1-propanol, 1-pentanol, 1-hexanol, 1-octanol, and chloroform were used as solvents because they provide a wide range of viscosity. The spin exchange rate constants measured in the different solvents ranged from 3 × 10⁸ to 8 × 10⁹ M⁻¹ s⁻¹, and from 7 × 10⁸ to 1 × 10¹⁰ M⁻¹ s⁻¹ for the TEMPO/Fe(acac)₃ and the TCNE/Fe(acac)₃ systems, respectively. The spin exchange rate constants, k _e, are compared with the corresponding diffusion rate constants. It was found that the k _e values correlate well with those of diffusion and hence the intermolecular spin exchange is strongly diffusion-controlled. The activation energies and pre-exponential factors are calculated from the Arrhenius plots.     

Effects of 1064 nm laser on the structural and optical properties of nanostructured TiO2 thin film

TiO₂ thin film has been widely used as photoelectrode in dye-sensitized solar cells. It can also be used in quantum dot synthesized solar cells. Study of its effects in different spectrum of light is important for its use in solar cells. We have reported effects of 1064 nm laser on the surface morphology, structural and optical properties of nanostructured TiO₂ thin film deposited on glass substrates using sol-gel spin coating technique. Q-Switched Nd:YAG pulsed laser at various power densities is used in this study. Surface morphology of the film is investigated using X-ray diffraction (XRD) and atomic force microscopy technique. The XRD pattern of as deposited TiO₂ thin film is amorphous and after laser exposure it became TiO₂ anatase structure. Atomic force microscopy of the crystalline TiO₂ thin film shows that the grain size increases by increasing laser power density. The calculations of the band gap are carried out from UV/Visible spectroscopy measurements with JASCO spectrometer. For laser power density of 25 MW/cm² there is an increase in the transmission and it decreases at the value of 38 MW/cm² and band gap decreases with increasing laser power density. Photoluminescence spectra of the crystalline TiO₂ thin film indicate two broad peaks in the range of 415 and 463 nm, one for band gap peak (415 nm) and other for oxygen defect during film deposition process.     

Entangled coherent states for quantum information processing

Entangled coherent states (ECSs) with relative phase equal to the phase shift between two coherent states are constructed. We study the degree of entanglement and the nonclassical features exhibited by the so-constructed states keeping in view their role in quantum information processing (QIP).