Luminescence spectra and kinetics of disordered solid solutions

We have studied both theoretically and experimentally the luminescence spectra and kinetics of crystalline, disordered solid solutions after pulsed excitation. First, we present the model calculations of the steady-state luminescence band shape caused by recombination of excitons localized in the wells of random potential induced by disorder. Classification of optically active tail states of the main exciton band into two groups is proposed. The majority of the states responsible for the optical absorption corresponds to the group of extended states belonging to the percolation cluster, whereas only a relatively small group of “radiative” states forms the steady-state luminescence band. The continuum percolation theory is applied to distinguish the “radiative” localized states, which are isolated in space and have no ways for nonradiative transitions along the tail states. It is found that the analysis of the exciton-phonon interaction gives the information about the character of the localization of excitons. We have shown that the model used describes quite well the experimental cw spectra of CdS(1−c)Sec and ZnSe(1−c)Tec solid solutions. Further, the experimental results are presented for the temporal evolution of the luminescence band. It is shown that the changes of band shape with time come from the interplay of population dynamics of extended states and spatially isolated “radiative” states. Finally, the measurements of the decay of the spectrally integrated luminescence intensity at long delay times are presented. It is shown that the observed temporal behavior can be described in terms of relaxation of separated pairs followed by subsequent exciton formation and radiative recombination. Electron tunneling processes are supposed to be responsible for the luminescence in the long-time limit at excitation below the exciton mobility edge. At excitation by photons with higher energies the diffusion of electrons can account for the observed behavior of the luminescence

Hybrid nanoparticles based on sulfides, oxides, and carbides

The methods for synthesis of hybrid nanoparticles based on sulfides, oxides, and carbides of heavy and transition metals were considered. The problem of the influence of the method of synthesis of the hybrid nanoparticles on their atomic structure, morphology of the nanomaterials, and functional properties was analyzed. The areas of practical use of the hybrid nanoparticles were proposed. © 2013 Springer Science+Business Media New York

Probing "green"€� industry enterprises in the UK: A new identification approach

AbstractThere is a growing interest in innovation for sustainability and the development of green industries and green jobs. But how can green industries, green manufacturing jobs, and green goods innovation be measured? This paper probes current and recent attempts to define and measure these categories, with a focus on studies in the UK. We review the methods, estimates and trends contained in these studies. While these efforts have value, they also raise significant conceptual and measurement issues. The paper discusses a series of these issues and considers strategies to further refine the categorization and detection of green sector enterprises. A new identification approach is put forward using search term combinations and text mining to discern green goods sector companies. This method is tested through a search of small and medium-size green goods enterprises in the UK. Findings from our search approach are presented, along with a discussion of advantages and limitations

ВЛИЯНИЕ ГИП НА СТРУКТУРУ И СВОЙСТВА МОНОКРИСТАЛЛИЧЕСКИХ ЛОПАТОК ИЗ СПЛАВА ЖС26-ВИ

The hot isostatical pressing was provided by the substantial decline of contraction microporosity of the cooled shoulder-blades of turbines of single-crystals from the alloy of ЖС26-ВИ, that improved homogeneity their microstructure and promoted physic-mechanical properties. For such shoulder-blades the optimum mode of heat treatment and rational chart of superficial gas operating norms to the responsible details of GTE.Горячее изостатическое прессование обеспечило существенное снижение усадочной микропористости монокристаллических турбинных охлаждаемых лопаток из сплава ЖС26-ВИ, что улучшило однородность их микроструктуры и повысило физико-механические свойства. Для таких лопаток определены оптимальный режим термообработки и рациональная схема поверхностного газового алитирования. Качественные показатели полученных лопаток вполне удовлетворяют требованиям действующих нормативов к ответственным деталям ГТД