Morphology Controlled Energy Transfer in Conjugated Molecular Thin Films

In α‐sexithienyl (T₆) molecular thin films the spectral features of photoluminescence can be correlated to precise structural topologies and the nature of photoluminescence can be controlled. AFM images show that the topological features of T₆ films evolve progressively from 2D to 3D structures with film thickness. It is shown that coalescence between different domains results in photoluminescence spectra that are dominated by the aggregate emission. The Figure shows the photoluminescence spectra of submonolayer and lamellae architectures.     

Synthesis and temperature-dependent optical properties of Eu3+-doped NaYSiO4 red-emitting phosphors

Abstract

Novel Eu³⁺-activated orthosilicate NaYSiO₄:xEu³⁺ (x?=?0.02, 0.05, and 0.20) red-emitting phosphors were developed for white light emitting diode applications. The X-ray diffraction (XRD), photoluminescence excitation and emission spectra, temperature-dependent curves were applied to characterize the samples. The red emission of the NaYSiO₄:Eu³⁺ phosphor corresponding to ⁵D₀→⁷F₂ (614?nm) transition was observed under the excitation of 394?nm wavelength, which is suitable for UV LED chip. The quenching temperature for NaYSiO₄:0.05Eu³⁺ was found to be over 500 K. The CIE chromaticity coordinates of NaYSiO₄:0.05Eu³⁺ are very close to the National Television System Committee (NTSC) standard red.     

Inside Front Cover: Green Synthesis and Property Characterization of Single‐Crystalline Perovskite Fluoride Nanorods (Adv. Funct. Mater. 1/2008)

The synthesis of single‐crystalline, cubic perovskite KMnF₃ and NH₄MnF₃ nanorods, and their rare‐earth‐ion‐doped analogues with reproducible shapes and sizes, has been realized using a modified template‐directed approach, report Stanislaus Wong and co‐workers on p. 103. The properties of the nanorods and their as‐doped counterparts suggest their practical incorporation into functional nanometer‐scale devices with applications in a number of fields. The cover shows the crystal structure of perovskite fluorides overlaid on a SEM image of as‐prepared KMnF₃ nanorods with diameters measuring around 50 nm. The generalized green synthesis of single‐crystalline KMnF₃ and NH₄MnF₃ nanorods as well as of their rare‐earth ion doped analogues, possessing reproducible shape and controllable size, has been achieved using a modified template‐directed approach under ambient room‐temperature conditions, with simple inorganic salts as functional precursors. Extensive characterization of the resulting nanorods has been performed using diffraction, electron microscopy, optical spectroscopy, as well as magnetic techniques. We have studied the antiferromagnetism of as‐prepared ternary metal fluoride nanorods as well as the luminescence of their as‐doped counterparts. Our collective data suggest the possibility of the incorporation of these high‐quality, chemically pure materials into functional nanoscale devices with various potential applications that exploit the interesting optomagnetic properties of these systems.     

Growth of high-quality, uniform c-axis-oriented zinc oxide nano-wires on a-plane sapphire substrate with zinc oxide templates

High-quality, vertically aligned zinc oxide (ZnO) nano-wires were grown by the vapour-transport method on (1 1 2¯ 0) (a-plane) sapphire substrate covered by a uniform ZnO nano-crystalline seed layer which was deposited in a preceding growth step via simple chemical vapour deposition. A thin layer of close-packed nano-seeds with an average size of 12 nm was formed rapidly on the substrate by sublimation and thermal decomposition of zinc acetate dihydrate as the precursor at moderate temperatures and pressures. Subsequently, growth of ZnO nano-wires was performed by a carbo-thermal vapour-transport method yielding nano-wires with high reproducibility and homogeneity. The as-grown, c-axis-oriented nano-wires exhibit excellent luminescence properties and perfect alignment with respect to the substrate surface.     

锗硅超晶格和多孔硅中的分波发光

锗硅超晶格和多孔硅的大量实验分析表明，其发光性能既不能用间接带隙来解释，也不同于直接光跃迁。本文通过波函数的谐波分析和表面化学键诱生的能带混合研究得出这两种材料中都可能产生出直接带隙分波，从而得到直接光跃迁。运用这种分波发光模型，解释了锗硅超晶格和多孔硅的大量实验结果。最后比较了这两种材料能带工程中的物理效应和化学效应，提出了综合此两效应优化设计新发光材料的新方法。     

Gap－LPE掺S浓度的控制及对发光效率的影响

报道了具有双ｎ型结构的ＧａＰ绿色发光二极管在汽相掺杂、液相外延过程中，对硫（Ｓ）掺杂浓度的控制和监测方法，并研究了掺Ｓ浓度对发光效率的影响。     

Wet Adsorption of a Luminescent EuIII complex on Carbon Nanotubes Sidewalls

A Eu^III complex, tris‐dibenzoylmethane mono‐1,10‐phenanthroline‐europium(III) [Eu(DBM) ₃ (Phen)] , can be easily adsorbed in situ via hydrophobic interactions to single‐walled carbon nanotube (SWNT) surfaces from a methanol solution. The Eu^III‐containing material has been comprehensively characterized via thermogravimetric analysis (TGA), UV‐vis‐NIR absorption and luminescence spectroscopy, Raman spectroscopy, atomic force microscopy (AFM), high‐resolution transmission electron microscopy (HR‐TEM)), Z‐contrast scanning transmission electron microscopy (STEM) imaging, and energy dispersive X‐ray spectroscopy (EDS). The photophysical investigations revealed that the presence of a SWNT framework does not affect the lanthanide‐centered luminescence stemming from the characteristic electronic transitions within the 4f shell of the Eu^III ions. Such straightforward synthetic route leads to the preparation of luminescent SWNTs without significantly affecting the electronic and structural properties of the carbon framework, opening new possibilities of designing new classes of CNTs for biomedical applications.     

爆燃型发光剂及装药

针对某型号试验战斗部发光性能的要求,研究了爆燃型发光剂的配方、工艺及装药条件,对其发光性能参数进行了测定。