Modelling of Optical Detection of Spin-Polarized Carrier Injection into Light-Emitting Devices

We investigate the emission of multimodal polarized light from Light Emitting Devices due to spin-aligned carriers injection. The results are derived through operator Langevin equations, which include thermal and carrier-injection fluctuations, as well as non-radiative recombination and electronic g-factor temperature dependence. We study the dynamics of the optoelectronic processes and show how the temperature-dependent g-factor and magnetic field affect the polarization degree of the emitted light. In addition, at high temperatures, thermal fluctuation reduces the efficiency of the optoelectronic detection method for measuring spin-polarization degree of carrier injection into non-magnetic semicondutors.Comment: 15 pages, 7 figures, replaced by revised version. To appear in Phys. Rev.

The lineage-defining factors T-bet and Bcl-6 collaborate to regulate Th1 gene expression patterns

T-bet acts as a functional repressor in association with Bcl-6 to antagonize SOCS1, SOCS3, TCF-1, and late-stage IFN-γ to regulate Th1 development

Stoichiometric and catalytic C-C and C-H bond formation with B(C6F5)3 via cationic intermediates

This work showcases a new catalytic cyclization reaction using a highly Lewis acidic borane with concomitant C−H or C−C bond formation. The activation of alkyne‐containing substrates with B(C6F5)3 enabled the first catalytic intramolecular cyclizations of carboxylic acid substrates using this Lewis acid. In addition, intramolecular cyclizations of esters enable C−C bond formation as catalytic B(C6F5)3 can be used to effect formal 1,5‐alkyl migrations from the ester functional groups to unsaturated carbon–carbon frameworks. This metal‐free method was used for the catalytic formation of complex dihydropyrones and isocoumarins in very good yields under relatively mild conditions with excellent atom efficiency

Stöchiometrische und katalytische C-C- und C-H-Bindungsbildung mit B(C6 F5 )3 über kationische Zwischenstufen

Diese Arbeit beschreibt eine neuartige katalytische Cyclisierung unter Verwendung eines stark Lewis-sauren Borans mit einhergehender C-H- oder C-C-Bindungsbildung. Die Aktivierung von Molekülen mit C-C-Dreifachbindungen unter Verwendung von B(C6F5)3 ermöglicht erstmals eine entsprechende Lewis-Säure-katalysierte, intramolekulare Cyclisierung von Carbonsäuren. Darüber hinaus zeigen die Ester dieser Carbonsäuren mit katalytischen Mengen B(C6F5)3 eine formale 1,5-Migration der Estergruppen unter Knüpfung einer C-C-Bindung. Unter Verwendung dieser neuen metallfreien Methode konnten anspruchsvolle Dihydropyrone und Isocumarine in hohen Ausbeuten unter milden Bedingungen sowie mit hoher Atomökonomie synthetisiert werden

Spin dynamics in semiconductors

This article reviews the current status of spin dynamics in semiconductors which has achieved a lot of progress in the past years due to the fast growing field of semiconductor spintronics. The primary focus is the theoretical and experimental developments of spin relaxation and dephasing in both spin precession in time domain and spin diffusion and transport in spacial domain. A fully microscopic many-body investigation on spin dynamics based on the kinetic spin Bloch equation approach is reviewed comprehensively.Comment: a review article with 193 pages and 1103 references. To be published in Physics Reports

Silylium-ion-promoted (5+1) cycloaddition of aryl-substituted vinylcyclopropanes and hydrosilanes involving aryl migration

A transition-metal-free (5+1) cycloaddition of aryl-substituted vinylcyclopropanes (VCPs) and hydrosilanes to afford silacyclohexanes is reported. Catalytic amounts of the trityl cation initiate the reaction by hydride abstraction from the hydrosilane, and further progress of the reaction is maintained by self-regeneration of the silylium ions. The new reaction involves a [1,2] migration of an aryl group, eventually furnishing 4- rather than 3-aryl-substituted silacyclohexane derivatives as major products. Various control experiments and quantum-chemical calculations support a mechanistic picture where a silylium ion intramolecularly stabilized by a cyclopropane ring can either undergo a kinetically favored concerted [1,2] aryl migration/ring expansion or engage in a cyclopropane-to-cyclopropane rearrangement.DFG, 390540038, EXC 2008: Unifying Systems in Catalysis "UniSysCat"TU Berlin, Open-Access-Mittel – 202