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Electron-electron interaction in the presence of impurities is studied in two-dimensional systems where the parameter k(B)T tau/h changes from 0.1 to 10 (tau is the momentum relaxation time). This corresponds to the intermediate and ballistic regimes of electron interaction. We analyse the interaction correction to the Drude conductivity in terms of recent theories and show that it is strongly dependent on the character of the impurity potential. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

We study the crossover from 'metallic' to 'insulating' behaviour of the 2DEG in a vicinal Si MOSFET and 2DHG in a GaAs/GaAlAs heterostructure. It is shown that the crossover complies with a conventional Fermi-liquid approach. In the electron gas, it is caused by an impurity band at the Si/Si oxide interface. In the hole gas, the negative magnetoresistance near the crossover is well described by weak localisation, in spite of large values of interaction parameter r s ∼ 30. We also study p(T) and parallel magnetoresistance in the 'metallic' regime. It is shown that this regime is caused by phonon-scattering and hole-hole interaction correction in a disordered Fermi liquid.

Low temperature optical and photochemical properties of Rhodobacter sphaeroides (R-26) reaction centers, in which bacteriopheophytin a has been replaced by plant pheophytin a, are reported. Modified reaction centers preserve the ability for photoinduced electron transfer from the primary electron donor P to the primary quinone acceptor QA at 80K. The triplet state ESR signal of modified reaction centers with prereduced QA at 10K shows an electron spin polarization pattern and ZFS parameters analogous to those for the triplet state 3P in non-treated reaction centers. It was found that at low temperature both P+Q−A and 3P states are formed via a precursor radical pair P+I− in which I is the introduced plant pheophytin molecule. This shows that acceptor systems of bacterial and plant (photosystem II) reaction centers are mutually replacable in structural and functional aspects.

Cool-down after close-space sublimation growth of cadmium telluride films has been shown to lead to the formation of a Cd-rich surface that can block the subsequent in-diffusion of cadmium chloride that is used in post-growth doping of solar cell devices. Pre-etching of the as-grown surfaces using a nitric–phosphoric acid etch prior to doping leads to increase in chlorine and oxygen in-diffusion, and an associated improvement in device efficiency from 0.4 eV for etched devices. Impedance analysis showed the improved cadmium chloride treatment—resulting from the additional etching step—removed the grain boundary component from the equivalent circuit, indicating a grain boundary passivation effect. Copyright © 2011 John Wiley & Sons, Ltd.

Die Flussigphasenoxidation aliphatischer Ketone (untersucht am Beispiel des Diamylketons) bei 120-140°C und 15 at erfolgt zu uber 70% an den der CO- Gruppe benachbarten Methylengruppen unter Bildung entsprechender Carbonsauren.