Excimer-laser-assisted RF glow-discharge deposition of amorphous and microcrystalline silicon thin films

We combine the deposition of Hydrogenated amorphous Silicon (a-Si:H) by rf glow discharge with XeCl-excimer laser irradiation of the growing surface in order to obtain different kinds of silicon films in the same deposition system. In-situ UV-visible ellipsometry allows us to measure the optical properties of the films as the laser fluence is increased from 0 up to 180 mJ/cm² in separate depositions. For fixed glow-discharge conditions and a substrate temperature of 250° C we observe dramatic changes in the film structure as the laser fluence is increased. With respect to a reference a-Si:H film (no laser irradiation) we observe at low laser fluences (15–60 mJ/cm²) that the film remains amorphous but demonstrates enchanced surface roughness and bulk porosity. At intermediate fluences (80–165 m/Jcm²), we obtain an amorphous film with an enhanced density with respect to the reference film. Finally, at high fluences (165–180 mJ/cm²), we obtain microcrystalline films. The in-situ ellipsometry measurements are complemented by ex-situ measurements of the dark conductivity, X-ray diffraction, and Elastic Recoil Detection Analysis (ERDA). Simulation of the temperature profiles for different film thicknesses and for three laser fluences indicates that crystallization occurs if the surface temperature reaches the melting point of a-Si:H ( 1420 K). The effects of laser treatment on the film properties are discussed by taking into account the photonic and thermal effects of laser irradiation.Presented at LASERION 93, Munich, June 21–23, 1993     

Spectral properties of random Schrödinger operators with unbounded potentials

We investigate spectral properties of random Schrödinger operators H = - + _n()(1 + |n|) acting onl ²(Z ^d), where _n are independent random variables uniformly distributed on [0, 1].Research partially supported by a Sloan Doctoral Dissertation Fellowship and NSERC under grant OGP-0007901Research partially supported by NSF grant DMS-9101716     

Nitrato- and fluoroboracites M3B7O13NO3 and M3B7O13F

New boracites containing nitrato- or fluoroanions that appear to be true low-pressure phases have been synthesized at superatmospheric pressures. The M₃B₇O₁₃NO₃ compounds (M = Co, Ni, Cu, Zn, Cd) transform rapidly and reversibly in the temperature region 300–500°C between probable orthorhombic and face centered cubic symmetry, while the M₃B₇O₁₃F compounds (M = Mg, Mn, Fe, Co, Zn) appear to maintain rhombohedral symmetry up to their decomposition temperatures of 800–900°C. True high-pressure boracite-like phases containing F and Cr, Mn, Fe, or Co that decompose upon heating to M₃B₇O₁₃F have also been isolated.     

拟薄水铝石/陶瓷胶态加工浆料的流变性能

用拟薄水铝石纳米胶粒分散微米二硼化钛形成固含量为60Wt%的稳定陶瓷浆料,实验考察了拟薄水铝石固含量、二硼化钛固含量、温度对浆料流变性、稳定性的影响,对纳米γ-AlOOH胶粒分散微米TiB2的机制进行了讨论.大小约20nm的γ-AlOOH颗粒相互网联,成为外加微米陶瓷颗粒的骨架.浆料粘度随二硼化钛固含量的增加而增大,温度升高有利于胶体中薄水铝胶团与二硼化钛颗粒的相互作用并促进分散.     

Studium der Reduktion von Resazurin

Zusammenfassung In dieser Arbeit wurden Schlußfolgerungen über den simultanen Verlauf der beiden Reduktionsphasen von Resazurin überprüft.Weiters wurden Bedingungen für die quantitative titanometrische Bestimmung von Resazurin und seiner Derivate ermittelt.

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The conclusions about the simultaneous course of reduction of Resazurin to Resorufin and Resorufin to Dihidroresorufin were verified in this work.The conditions for the quantitative titanometric determination of Resazurin and its derivatives were found.

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Mit 4 Abbildungen     

Flow injection analysis : Part IX. A New Approach to Continuous Flow Titrations

Studies of dispersion patterns in nonsegmented streams, flowing through narrow open tubes, show that it is possible to obtain highly reproducible concentration gradients within a sample zone injected into the moving stream. By varying the geometry of the flow path, low, medium and high dispersion patterns can be achieved; the high dispersion pattern forms the basis for a new approach to continuous flow titrimetry. In this type of titration, discrete samples are passed through a gradient device and are then mixed with a continuously flowing stream of titrant of fixed concentration. The new technique has been tested for potentiometric as well as spectrophotometric end-point indication. A simple one-channel system allows titrations to be performed automatically in less than 1 min.     

Determination of heptacaine hydrochloride in solution using nuclear analytical methods

The applicability of two nuclear analytical methods for the determination of hepatacaine hydrochloride in solution was studied, i. e. radionuclide X-ray fluorescence analysis and radiometric titrations based on precipitate formations. Methods used were evaluated on the basis of obtained sensitivity values.