Effects of unsymmetrical geometric confinements on depletion interactions in colloidal suspensions

The depletion interactions between two large-spheres immersed in a fluid of small spheres under unsymmetrical geometrical confinement are studied through the acceptance ratio method. The numerical results show that no matter whether the volume fraction is large or small, both the depletion potential and depletion force are affected by the presence of the two plates; the closer the two large spheres are to the plate, the larger the effects of the unsymmetrical confinements.     

Noise performance analysis of bi-directionally pumped distributed fiber Raman amplifiers with consideration of fiber nonlinearity and its impact on EDFA output OSNR

Under small-signal assumption, equivalent noise figure normalized by fiber nonlinearities (NENF) of bi-directionally pumped distributed fiber Raman amplifiers (BiDFRA) is derived. Amplified spontaneous Raman scattering noise and double Rayleigh scattering noise are both included. The relation between NENF and Raman gain, forward Raman gain percentage is investigated under different polarization factor and Rayleigh scattering coefficient. It agrees well with numerical simulation results. Based on the analytical expression, the optical signal-to-nose ratio (OSNR) improvement of hybrid pre-BiDFRA/erbium-doped fiber amplifier (EDFA) compared with sole EDFA is studied. It is shown that there is an optimum Raman gain and forward Raman gain percentage to maximize the OSNR improvement. Finally, some guidelines on BiDFRA design are proposed.     

激发态RbHe(Ar)分子的光离解

本文研究了Rb（5^2P) He(Ar) nhv→Rb(7^2D) He(Ar) n-1)hv过程，激光频率调离Rb7D5/2→5P3/2跃迁谱线20－100cm^-1，测量了精细结构普线强度分支出I（7D3／2→5P1／2）／I（7D5／2→5P3／2）。测量结果表明，原相互作用势和非绝热效应在分子离解动力学中起关键作用。     

基于氟掺杂双芯光子晶体光纤偏振光分束器的设计及研究

在光子晶体光纤二氧化硅材料中掺入氟元素、在光纤中引入七个椭圆空气孔以及三角形和矩形周期性空气圆孔,设计了一种氟掺杂双芯光子晶体光纤偏振光分束器.对该分束器结构参量进行优化,对分束器分离两正交偏振光的性能进行分析.结果表明:在优化结构尺寸下,当光纤长度为102.717μm的超短长度时,在1.55μm波长处具有超强的分离两束正交偏振光的能力,消光比可以达到126.442dB,具有60nm的有效带宽.此偏振光分束器在大容量光通信系统中具有重要的应用价值.     

Measurement of stable isotope activities in saline aqueous solutions using optical spectroscopy methods

The requirement to measure the stable isotopic compositions of saline pore fluids by optical methods has prompted a re-evaluation of the isotopic salt effect for common salts. Hydrogen and oxygen isotopic salt effects were measured at room temperature (21°C) by optical methods. For hydrogen isotopes, our results agree well with those of previous studies and better define these effects at low temperatures. In contrast, measured oxygen isotope salt effects disagree within error for NaCl and CaCl₂ solutions from those reported previously. Subtle differences between measurement methods may account for the discrepancy. In studies that involve highly saline fluids, the isotopic salt effect must be taken into account because modern methods that measure stable isotopic compositions as activities or concentrations may be not directly comparable to historical data sets.     

Grundlagen der Mehrstoffanalyse mit Elektronen- und ß-Strahlung,II. Experimentelle Untersuchungen zur effektiven Kernladungszahl für den Rückstreuprozeß

Messungen un Bleiverbindungen und wassersloffhaltigen stoffen mit β-Strahlung im Energiebereich von 0,2 bis 3 MeV zeigen, daβ die in Teil I abgeleitete Formel für die Ermittlung der Effektiven Kernladungszahl selbst bei Medien extremer Zusammensetzung anwendbar ist. Die in der Literatur häufig erwāhnten Abweichungen der errechneten Kernladungszahlen von den experimentell ermittelten Ergebnissen sind hauptsächlich auf unterschiedliche Probendichte und auf die Korngröβe der Proben zurückzuführen. In der vorliegenden Arbeit sind derartige Störungen durch entsprechende Auswahl der Meβbedingungen vermieden oder durch empirische korrekturen eliminiert worden.     

Untersuchungen zum Verhalten der Pt-Metalle gegenüber festen und flüssigen Kationenaustauschern mit Hilfe der Radiotracermethode

Mit Hilfe radioaktiver Nuklide wurde die Aufnahme der Pt-Metalle aus chloridhaltigen Lösungen sowoht durch feste (Wofatit KPS) als auch durch flüssige Kationenaustauscher (Bis-2-äthylhexylphosphorsäure) bei Variation des pH-Wertes, der Vorbehandlung sowie der Edelmetallkonzentration bestimmt. Pt und Ir wurden nur geringfügig, Pd und Rh dagegen deutlich stärker adsorbiert. Beide Austauschertypen zeigten qualitativ das gleiche Verhalten. Die gefundenen Abhängigkeiten der Adsorption wurden auf das komplexchemische Verhalten der Pt-Metalle zurückgeführt. Es werden Verfahren zur schnellen radiochemischen Reinigung der benutzten Nuklide angegeben.     

A Repaid Procedure for Preparing Oxyen-18 Determination in Water Samples

An equipment for the speed δ¹⁸O analysis of water samples is described. It used the equilibrium isotopic exchange reaction between water and CO₂ gas. Outgasing of samples through capillary without freezing down the samples, together with shaking during the equilibrium time, reduced considerably time for sample preparation.

Apparatus is air termostated with hand valves. Measured δ values are not very sensitive to precision of preparation work and reaction conditions, except of temperature. With good temperature control the standard reproducibility of single measurement is better than 0,1‰     

Stable Isotope Geochemistry of Antarctic Salt Efflorescences

Salt efflorescences consisting of gypsum sampled mainly in the Schirmacher Oasis have been analyzed for the isotopic composition of the water of crystallization and of the sulphate-sulphur. For comparison, a few samples from other Antarctic locations (Guettard Range, Prince Charles Mts., Insel Mts.) were included in the study. The isotopic variations of the water of crystallization of secondary gypsum and the calculated isotopic composition of the mother solution reflect the local climatic conditions during the precipitation of the efflorescences. It is therefore possible to obtain qualitative information about the climatic conditions prevailing in the studied region.