Facile synthesis of nanosized ε-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> particles on the silica support

An approach is suggested to synthesize the ε-Fe₂O₃ particles supported on silica with the mean size of few nanometers, narrow size distribution and no admixture of any other iron oxide polymorphs. The facile synthesis is based on the pore filling impregnation method by iron sulfate (II) water solution with the following annealing procedure at ~1173 K. It is shown that the ε-Fe₂O₃ nanoparticles obtained are stable up to ~1173 K and possess superparamagnetic behavior up to ~870 K.     

Formation conditions of a magnetically ordered phase ɛ-Fe2O3. A FMR in situ study

The ferromagnetic resonance (FMR) method in situ is used to study the initial stages of the formation of ? iron oxide nanoparticles deposited on silica gel at temperatures up to 600°C. It is shown that at high-temperature treatment of starting samples obtained by impregnation with an iron(II) sulfate solution, supermagnetic ?-Fe₂O₃/SiO₂ nanoparticles form with a narrow size distribution. An analysis of the FMR data in comparison with the data of other methods enables the formulation of the formation conditions for systems of deposited ?-Fe₂O₃ nanoparticles without other polymorph impurities.     

Structural defects cause TiO2-based photocatalysts to be active in visible light

Oxidation of TiO or Ti2O3 led to the formation of TiO2 with activity in visible light much higher than when TiN was used as a precursor, pointing out the importance of oxygen defects/vacancies for extension of activity of TiO2 into the visible region.     

Ultrafast charge photogeneration dynamics in ground-state charge-transfer complexes based on conjugated polymers

The charge photogeneration and early recombination in MEH-PPV-based charge-transfer complexes (CTCs) and in MEH-PPV/PCBM blend as a reference are studied by ultrafast visible-pump-IR-probe spectroscopy. After excitation of the CTC band, an immediate (<100 fs) electron transfer is observed from the polymer chain to the acceptor with the same yield as in the MEH-PPV/PCBM blend. The forward charge transfer in the CTCs is followed by an efficient (approximately 95%) and fast (<30 ps) geminate recombination. For comparison, the recombination efficiency obtained in the MEH-PPV/PCBM blend does not exceed a mere 50%. Polarization-sensitive experiments demonstrate high (approximately 0.3) values of transient anisotropy for the CTCs polaron band. In contrast, in the MEH-PPV/PCBM blend the dipole moment orientation of the charge-induced transition is less correlated with the polarization of the excitation photon. According to these data, photogeneration and recombination of charges in the CTCs take place locally (i.e., within a single pair of a polymer conjugation segment and an acceptor) while in the MEH-PPV/PCBM blend exciton migration precedes the separation of charges. Results of the ultrafast experiments are supported by photocurrent measurements on the corresponding MEH-PPV/acceptor photodiodes.     

Photochemical cyclocondensation of 1-arylthio-2-azidoanthraquinones with phenols

Russian Chemical Bulletin - Photolysis of 1-arylthio-2-azidoanthraquinones in DMSO in the presence of phenols leads to the formation of 5H-naphtho[2,3-c]phenothiazine-8,13-diones, in which the...     

离子型共聚单体参与下的全氟丙烯酸酯无皂乳液共聚

离子型共聚单体参与下的全氟丙烯酸酯无皂乳液共聚;全氟烷基丙烯酸酯;无皂乳液;离子型共聚单体     

A 1.107 μm Yb3+-doped Phosphate Fiber Laser Pumped by a Ti:sapphire

Lasers and amplifiers in a single fiber have been developed rapidly, especially for optical fiber communication and various sensors, in the recent years. However, remarkable progress and achievement have been made mainly in silica fiber doped with rare earth elements. In this paper, we report the progress on the development of the Yb3+-doped phosphate fiber laser.