Mott transition of excitons in coupled quantum wells

In this work we study the phase diagram of indirect excitons in coupled quantum wells and show that the system undergoes a phase transition to an unbound electron-hole plasma. This transition is manifested as an abrupt change in the photoluminescence linewidth and peak energy at some critical power density and temperature. By measuring the exciton diamagnetism, we show that the transition is associated with an abrupt increase in the exciton radius. We find that the transition is stimulated by the presence of direct excitons in one of the wells and show that they serve as a catalyst of the transition.     

Bulk-edge coupling in the non-Abelian nu=5/2 quantum hall interferometer

Recent schemes for probing non-Abelian statistics in the quantum Hall effect are based on geometries where current-carrying quasiparticles flow along edges that encircle bulk quasiparticles, which are localized. Here we consider one such scheme, the Fabry-Perot interferometer, and analyze how its interference patterns are affected by a coupling that allows tunneling of neutral Majorana fermions between the bulk and edge. While at weak coupling this tunneling degrades the interference signal, we find that at strong coupling, the bulk quasiparticle becomes essentially absorbed by the edge and the intereference signal is fully restored. Furthermore, we find that the strength of the coupling can be tuned by the source-drain voltage.     

Multistage polar switching in bent-core mesogens

We report a novel type of electro-optical switching in a tilted smectic phase of bent-shaped mesogens. The switching consists of a continuous stage and two bistable transitions. Detailed optical and electro-optical measurements using high-speed imaging are given and possible interpretations of the experimental results are discussed.     

Thermal and chemical equilibrium for vaporizing sources

Vaporized sources produced in collisions between ³⁶Ar and ⁵⁸Ni at 95 MeV per nucleon have been detected with the multidetector INDRA. Complete information concerning the deexcitation properties of quasi-projectiles, including second moments of chemical composition, is compared to a quantum statistical model describing a gas of fermions and bosons in thermal and chemical equilibrium. Inclusions in the calculation of all known discrete levels of nuclear species which deexcite into light particles and of a final state excluded volume interaction are found decisive to very well reproduce the experimental data, which strongly supports that thermodynamical equilibrium was achieved at freeze-out for such sources. Received: 6 April 1999     

pH和盐类对非离子型表面活性剂所组成微乳液的异常流变性影响

以非离子型表面活性剂AEO~9、正十六烷、正己醇和水所组成的微乳液为对象, 研究盐和pH值对其粘度和流变性的影响, 得出它们在pH值为7时最小, 以及二价盐影响最大的结论, 正好与离子型微乳液结果相反, 为此进行了讨论。并从热效应和电导对其微观结构作了初步探索。     

ChemInform Abstract: Copper(I) and Copper(II) Coordination Structure under Hydrothermal Conditions at 325 °C: An X‐Ray Absorption Fine Structure and Molecular Dynamics Study.

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