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Wavelength Emission (wavelength + emission)
Selected AbstractsFluorescent behavior of 2-(3,4,5,6-tetrafluoro-2-hydroxyphenyl)imidazo-[1,2- a]pyridine in the presence of metal perchlorateJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 2 2007Kiyoshi Tanaka 2-(3,4,5,6-Tetrafluoro-2-hydroxyphenyl)imidazo[1,2- a]pyridine (1) emits long wavelength light around 540 nm both in polar and in nonpolar solvents. Zn2+ perchlorate in acetonitrile causes the intermediate wavelength emission around 430 nm, which is ascribed to the species where the imidazole nitrogen atom and the phenolate oxygen atom bridge Zn2+. In the presence of Hg2+ and Al3+ perchlorates, short wavelength emission around 370 nm is strongly increased and this fluorescent enhancement is attributable not to the coordination of Hg2+ and Al3+ to 1 but to the formation of the salt of perchloric acid of 1. [source] A Wide-Bandgap Semiconducting Polymer for Ultraviolet and Blue Light Emitting Diodes,MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 18 2003Ping Lu Abstract A novel wide-bandgap conjugated polymer (PDHFSCHD) consisting of alternating dihexylfluorene and rigidly twisted biphenyl units has been synthesized. The new fluorene-based copolymer composed of rigid twisting segments in the main-chain exhibits an optical bandgap of as high as 3.26 eV, and a highly efficient ultraviolet emission with peaks at 368 nm and 386 nm. An electroluminescence device from PDHFSCHD neat film as an active layer shows UV emission which peaks at 395 nm with a turn on voltage below 8 V. By optimizing the device conditions, a peak EL quantum efficiency of 0.054% and brightness of 10 cd,·,m,2 was obtained. Furthermore, blending a poly(dihexylfluorene) in the PDHFSCHD host gave pure blue emission peaking at 417 nm and 440 nm without long wavelength emission from aggregated species. Efficient energy transfer from PDHFSCHD to PDHF was demonstrated in these blended systems. Depressed chain-aggregation of PDHF in the PDHFSCHD host can correspond to pure blue emission behaviors. The structure of the copolymer PDHFSCHD. [source] InAs quantum dots on GaAs substrates with InGaAs strain reducing layer for long wavelength emissionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003S. Saravanan Abstract InAs QDs on GaAs substrates were grown by molecular beam epitaxy (MBE). The dot density and properties were studied by atomic force microscopy (AFM). The low temperature photoluminescence (PL) characteristics of InAs QDs with different cap layers are discussed. The results suggest that InAs QDs covered by two InGaAs layers with different indium composition have long wavelength emission without much reduction in the PL intensity. [source] Charge-density analysis of the ground state of a photochromic 1,10-phenanthroline zinc(II) bis(thiolate) complexACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2010Stephan Scheins The charge density of the title compound was determined at 90,K, using a spherical crystal of 150,µm diameter. The proper treatment of the Zn atom in the pseudo-tetrahedral environment is considered in detail. A satisfactory refinement is only obtained when anharmonic Gram,Charlier parameters are included as variables in the refinement. A successful combined anharmonic/multipole refinement indicates a small polarization of the 4s shell in the anisotropic environment. One of the two toluenethiols is approximately ,-stacked with the phenanthroline ligand. A bond path is found connecting the two ligands. In addition the Zn,S bond to this ligand is slightly extended compared with the same bond to the second toluenethiol. A separate photocrystallographic and theoretical study indicates the long wavelength emission of the title compound to be due to a ligand-to-ligand charge transfer (LLCT) from a toluenethiol to the phenanthroline ligand. The charge-density results do not provide a basis for deciding which of the thiole ligands is the source of the transferred electron density. This result is in agreement with the theoretical calculations, which show comparable oscillator strengths for charge transfer from either of the ligands. [source] | ||||||||||