A free electron laser (FEL) amplifier with a curved parallel plate waveguide and a planar wiggler is presented. A set of operating equations for this FEL amplifier is derived by using the three-dimensional nonlinear theory. The characteristics including the evolution of power, efficiency and bandwidth of the FEL operating at the frequency of 94 GHz are numerically analyzed. The effects of electron energy spread and wiggler taper on saturation efficiency are also studied.

Electrochemical behaviors of different pendant carbazole based oligomers have been studied for the realization of electroactive tridimensional structures. 3-substitution by hydrazone functional groups onto the pendant carbazole moieties increases the electron donor properties of the electroactive units. Electrochemical oxidation of thin films of the oligomer precursors deposited onto electrode ensures the formation of a cross-linked structure by in situ anodic coupling with the formation of biscarbazole redox sites. When the electrochemical cross-linking of the oligomers is realized in the presence of the electron acceptor polyimide (perylene based), we form a semi-interpenetrating polymer network (semi-IPN) coated as a thin layer. The electrochemical behavior of the semi-IPN shows two reversible oxidations and two reversible reduction peaks indicating respectively the p-doping of the biscarbazole entity and the n-doping of the perylene one. The presence of hydrazone substituents modifies the electron donor properties of the semi-IPN and should influence the electron transfer properties from biscarbazole to perylene units in bulk heterojunction solar cells.

Small form factor optical disk (SFFOD) with a diameter of 27.4 mm was prepared for a mobile application. Near-field recording (NFR) technology with a flying optical head is applied to SFFOD for high density and small volume. A problem of contamination was observed at the head-disk interface (HDI) for first-surface recording. As a solution of the problem, a cover-layer was laminated onto the disk to move the focal plane into the media, which could solve the contamination problem. An edge bead free cover-layer could be coated with UV curable resin by using an outer-ring technique during the spin coating process. A diamond-like carbon (DLC) film and a lubricant film were coated on the disk to reduce the HDI problems.

Tl2Ba2CaCu2Oy(Tl-2212) thin films were fabricated on (001) LaAlO3 substrates by a two-step technique in a semi-closed aluminate crucible and a sealed steel container, respectively. First, the amorphous precursor films were deposited by the pulsed laser deposition (PLD) method, and then they were thalliated in different containers. Almost pure phase Tl-2212 thin films can be prepared in both of the containers. However, the as-annealed films show obvious differences in superconducting properties and microstructure.

The determination of the optical trajectories on which the radiative energy is transported has been achieved by solving the anisotropic Fermat's principle in a sphere of uniaxial semi-transparent material when the dielectric perpendicular and parallel permittivities are space dependant; first established for the general case of an optical axis function of the location inside the medium, it has completely been solved for the particular case of a constant optical axis with a constant anisotropy factor when the perpendicular permittivity is a function of the radius; the calculation shows a lack of the spherical symmetry due to the presence of the optical axis which induces non planar trajectories contrarily to the isotropic case.

GaN nanorods have been successfully synthesized on Si(111) substrates by magnetron sputtering through ammoniating the Ga2O3/ZnO films at 950 °C in a quartz tube. The GaN nanorods have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission transmission electron microscope (FETEM), Fourier transform infrared (FTIR) system and fluorescence spectrophotometer. The results show that the nanorods are pure hexagonal GaN wurtzite structure with lengths of about several micrometers and diameters ranging from 100 nm to 750 nm, and the growth direction of GaN nanorods is perpendicular to (101) plane. The photoluminescence (PL) spectrum indicates that the good emission property for the nanorods. Finally, the growth mechanism is also briefly discussed.

Electrochemistry of perylene imide and anhydride derivatives adsorbed on semiconductor TiO2 (NT) and insulator Al2O3 (NA) metal oxide films were presented. Adsorption rates on metal oxide surface are observed to be strongly depending on molecular structure. Monoanhydride-monoimide derivatives show two reversible reductions in solution and one reversible reduction in films. Color change from red to blue and violet is observed indicating the formation of monoanion and dianion radicals. Spectroelectrochemical measurements support this interpretation. The color reversal is quite stable in NA films in comparison with NT films.

We have studied blends of poly-(3-octylthiophene) (P3OT) and graphitic nanoparticles by macroscopic transport measurements, Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and Scanning Force Microscopy (SFM) techniques. Their morphology as well as their mechanical and electrical properties have been characterized on a nanometer scale as a function of the carbon nanoparticle concentration in the blend. For intermediate concentrations (5–10% wt. of carbon nanoparticles) the samples present regions of pure poly-(3-octylthiophene) and round regions of polymer and carbon nanoparticles mixture, while for higher concentrations (>15% wt.) the whole sample is composed of this mixture. The interface between both regions is studied by Electrostatic Scanning Force Microscopy as a function of the applied tip-sample voltage finding evidence for the creation of new electronic states at the heterojunction. TEM images show crystalline domains of P3OT surrounded by amorphous regions. XRD measurements show that the crystallinity of the polymer increases when carbon nanoparticle concentration increases. The potential of this blends to improve the performance of organic solar cells when used as active layer is discussed.

We report energy transfer from polyfluorene containing binaphthyl, P(BiNDO-FO3), to the europium complex, Eu(dnm)3phen. The P(BiNDO-FO3) has an electroluminescence (EL) peak at 422 nm where as pure polyfluorene (PF) has an EL peak at 438 nm. We have doped both polymers and report energy transfer in P(BiNDO-FO3), which is not present in PF. This is due to overlap of the absorption spectrum in the Eu(dnm)3phen with the emission spectrum of the P(BiNDO-FO3) while there is no overlap with the emission spectrum of PF.

An algorithm for generating and connecting 3-D nonconforming mesh with Finite Volume Method FVM is developed. The accuracy and computational performance using the nonconforming mesh technique are compared with those using the conventional conforming mesh. The algorithm is applied to solve a 3-D magnetostatic workshop problem proposed by IEEJ. It is shown that the memory requirements and CPU time using the nonconforming mesh can be decreased to about 1/2 of those using the conforming one. Moreover, the accuracy of the magnetic flux density is significantly improved.

We demonstrate, by means of light-induced EPR and optical spectroscopy, that thermal treatment of P3HT/PCBM films prepared from CB solution results in a decrease of the charge transfer yields. The improved performance of solar cells is therefore attributed to optimization of the morphology, in particular molecular order in the P3HT regions, which could be monitored by optical absorption and resonant Raman scattering (RRS). We further found that spin coating from slowly evaporating solvents leads directly (i.e., without thermal treatment) to optimal morphologies of the P3HT/PCBM films, with similar results for charge transfer, morphology and solar cell efficiencies.

Nano-crystalline magnetic alloys of Fe-Ni and Fe-Co are fabricated by high-energy milling. The coexistence of bcc and fcc lattice structures is observed in some of Fe-Ni alloys, as opposed to Fe-Co ones which exhibit the bcc phase only. The grain sizes increase linearly with the lattice strains for Fe-Co, and exponentially so for Fe-Ni. The cut-off frequency decreases with increasing nickel content in Fe-Ni alloys, but increases with increasing cobalt content in Fe-Co alloys. The larger the cut-off frequency is, the smaller the initial permeability. Resonant behaviour is observed in the pure Fe and Fe-Ni samples, which is replaced by relaxant behaviour in Fe-Co, implying that the Co plays an important role in hindering the resonance. The initial permeability at 10 kHz varies inverse proportionally with the coercivity Hc. It reaches a maximum while Hc goes to a minimum at 7.69 at.% Ni or Co. It is interesting that average atomic moments of nanocrystalline alloys are inconsistent with the Slater-Pauling relation.

The optical constants of azo dye (Methyl Red (MR)) and azo dye doped polymer (ADP) (Polymethylmethacrylate (PMMA)) MR/PMMA have been investigated using Variable Angle Spectroscopic Ellipsometry (VASE). Pure MR was modeled using Lorentz formula with three oscillators. A Bruggmann effective medium approximation layer was employed with three constituents (MR, PMMA and void) to represent the thin film of MR/PMMA. The optical constants of MR/PMMA were determined at various MR concentrations. The results reveal that the optical constants of the blend system are a linear interpolation of the two constituents. Average optical constants were determined using multiple sample analysis.

An algorithm was developed for the theoretical intensities of both X-ray continuum and characteristic K-radiation (Kα1, Kα2, Kα, Kβ1, Kβ2, Kβ3, Kβ13, Kβ4 and Kβ5) of different target materials (Cr, Cu, Rh, Mo, W, Ag and Au) at different electron incidence angles (0.01° − 90°), different take-off angles of the photon emission (0.01° − 90°) and different X-ray tube voltages. It was found that the intensities of continuum and characteristic X-rays increase with increasing take-off angle and the take-off angle is inversely proportional to the absorption path of X-rays in the target. At take-off angles of 20° or more, the flux of the X-ray spectra remains practically independent of the take-off angle. Furthermore, at the optimum electron incidence angle and take-off angle of emitted X-ray photons, the dependence of X-ray tube spectra on applied voltage was also investigated.

Highly stable single axial mode operation is obtained in a pulsed injection seeded oscillator with an adjustable pulse length from 20 ns to more than 50 ns, at a constant output energy. The adjustment principle is described experimentally and analysed theoretically. The peak to peak time jitter added to a slow time drift is of the order of 1 nanosecond for a 20 nanoseconds pulse length.

PbO-Sb2O3-B2O3 glasses containing different concentrations of MoO3 ranging from 0 to 5 mol % were prepared. A number of studies have been carried out on these glasses comprising differential thermal analysis, infrared and optical absorption, Raman and ESR spectra, magnetic susceptibility and measurements of dielectric properties (constant ε′, loss tan δ and a.c. conductivity $\sigma_{ac}$ over a range of frequency and temperature) of these glasses. The results have been analyzed in terms of different oxidation states of molybdenum ions. The analysis indicates that when the concentration of MoO3 is ≤0.6 mol %, molybdenum ions exist mostly in the Mo6+ state, occupy network forming positions with MoO$_{4}^{2-}$ structural units and increase the rigidity of the glass network. When MoO3 is present in higher concentrations, molybdenum ions seem to exist mostly in the Mo5+ state and occupy modifying positions.

A new halosulphate phosphor NaMgSO4F:Ce3+ and Na3SO4F:Ce3+ was synthesized by wet chemical method. The PL emission spectra of phosphors show strong Ce3+ emission due to the $5d\to 4f$ transition of Ce3+ ions. Ce3+ emission in new halosulphates NaMgSO4F and Na3SO4F lattice may be useful for a scintillation application. XRD and photoluminescence (PL) characterization of phosphors has been reported in this paper.

A model organic material, namely the 36-n-alkane hexatriacontane, was etched in a dissymmetrical parallel plate RF plasma reactor and a dual distributed electron cyclotron resonance (DECR) plasma reactor, in different O2-Ar mixtures. A specific attention was paid to the role of the ion bombardment, especially when its effect is combined with the chemically active species created in an oxygen discharge. The discharge was monitored by optical emission spectroscopy (OES). The modifications induced by plasma treatment on the structure of the material were analysed by Fourier transform infrared spectroscopy (FTIR), steric exclusion chromatography (SEC) and composition analysis. We found that the ion bombardment has not only a sputtering effect but also enhances the reaction rate of the chemical species on the layer surface. It appears that plasma treatment leads to cross-linking and recombination with molecules from the room atmosphere.

Positron annihilation was used to characterize vacancy-type defects in two types of polycrystalline Si grown at temperatures above ~800 °C by chemical vapour deposition. The majority of vacancies (80%) consisted of monovacancies, and their thermal stability indicated them to be trapped at grain boundaries or at dislocations. Annealing above 500 °C caused a significant reduction in the monovacancy concentration, and an increase in divacancy concentration. Divacancies started to anneal above 1200 °C. Measurements between 8 and 293 K indicated that vacancies were neutral before as well as after annealing at 1380 °C. Fz-grown Si from one of these materials contained vacancy clusters with an average size of six to ten vacancies which persisted to 1380 °C. The cluster concentration corresponded to a monovacancy concentration of 1015 to 1016 cm−3, which is at least one order of magnitude larger than estimates based on voids [R. Falster, V.V. Voronko, F. Quast, Phys. Status Solidi B 222, 219 (2000)].

Foils of Polymethyl methacrylate (PMMA) 2 mm thick were studied by measuring the total Secondary Electron Emission yield $\sigma $ (SEE yield) in a dedicated Scanning Electron Microscope especially equipped to study the fundamental aspects of the charge transport and trapping in insulating materials. The intrinsic SEE yield $\sigma _{0}$, (yield of the uncharged material) and the charging kinetics were studied under low current density $J=10^{+5 }$ pA/cm2. The curve of the primary beam energy variation of $\sigma _{0}$ exhibits a maximum intrinsic yield $\sigma _{\rm 0max}= 2.2$ at 370 ± 20 eV and two crossover energies $E_{I}=84$± 20 eV and $E_{II }=1465$± 20 eV for which $\sigma _{0} = 1$. For $\sigma _{0} >$ 1 PMMA is positively charged and negatively for $\sigma _{0} <$ 1. As electron injection is proceeding under the low current density used, the SEE yield varies from $\sigma _{0}$ to the steady value $\sigma _{st}=1$. This value that expresses the equality between the average number of emitted and injected electrons, characterizes the steady charge regime called “Self-Regulated Regime”. The evolution of $\sigma $ during the injection process is due to the internal field that blocks or enhances the secondary electron emission, according to the positive or negative nature of the trapped charges. A current density effect, characterized by a steady SEE yield slightly higher than unity, $\sigma _{st }=1.03$, instead of one, is observed at high energy (for example 4000 eV) for a strong current density $J>10^{+6 }$ pA/cm2. It is interpreted by a field ionisation (Poole-Frenkel type) that enhances the secondary electron emission.