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PL Emission (pl + emission)
Selected AbstractsPhotoluminescence Detection of Biomolecules by Antibody-Functionalized Diatom BiosilicaADVANCED FUNCTIONAL MATERIALS, Issue 6 2009Debra K. Gale Abstract Diatoms are single-celled algae that make microscale silica shells called "frustules", which possess intricate nanoscale features imbedded within periodic two-dimensional pore arrays. In this study, antibody-functionalized diatom biosilica frustules serve as a microscale biosensor platform for selective and label-free photoluminescence (PL)-based detection of immunocomplex formation. The model antibody rabbit immunoglobulin G (IgG) is covalently attached to the frustule biosilica of the disk-shaped, 10-µm diatom Cyclotella sp. by silanol amination and crosslinking steps to a surface site density of 3948,±,499 IgG molecules µm,2. Functionalization of the diatom biosilica with the nucleophilic IgG antibody amplifies the intrinsic blue PL of diatom biosilica by a factor of six. Furthermore, immunocomplex formation with the complimentary antigen anti-rabbit IgG further increases the peak PL intensity by at least a factor of three, whereas a non-complimentary antigen (goat anti-human IgG) does not. The nucleophilic immunocomplex increases the PL intensity by donating electrons to non-radiative defect sites on the photoluminescent diatom biosilica, thereby decreasing non-radiative electron decay and increasing radiative emission. This unique enhancement in PL emission is correlated to the antigen (goat anti-rabbit IgG) concentration, where immunocomplex binding follows a Langmuir isotherm with binding constant of 2.8,±,0.7,×,10,7M. [source] Efficient and Photostable ZnS-Passivated CdS:Mn Luminescent Nanocrystals,ADVANCED FUNCTIONAL MATERIALS, Issue 2 2004H. Yang Abstract Efficient and photostable ZnS-passivated CdS:Mn (CdS:Mn/ZnS core/shell) nanocrystals were synthesized using reverse micelle chemistry. CdS:Mn/ZnS core/shell nanocrystals exhibited much improved luminescent properties (quantum yield and photostability) over organically (n -dodecanethiol-) capped CdS:Mn nanocrystals. This is the result of effective, robust passivation of CdS surface states by the ZnS shell and consequent suppression of non-radiative recombination transitions. The dependence of photoluminescence (PL) intensity has been observed as a function of UV irradiation time for both organically and inorganically capped CdS:Mn nanocrystals. Whereas organically capped CdS:Mn nanocrystals exhibit a significant reduction of PL intensity, CdS:Mn/ZnS core/shell nanocrystals exhibit an increased PL intensity with UV irradiation. XPS (X-ray photoelectron spectroscopy) studies reveal that UV irradiation of CdS:Mn/ZnS nanocrystals in air atmosphere induces the photo-oxidation of the ZnS shell surface, leading to the formation of ZnSO4. This photo-oxidation product is presumably responsible for the enhanced PL emission, serving as a passivating layer. [source] New , -Conjugated Polymers Containing 1,3,5-Triazine Units in the Main Chain: Synthesis and Optical and Electrochemical Properties of the Polymers,MACROMOLECULAR RAPID COMMUNICATIONS, Issue 12 2005Shijie Ren Abstract Summary: Three new soluble , -conjugated polymers containing 1,3,5-triazine units in the main chain, Pa,Pc, were synthesized. The polymers showed optical properties in solution that were mainly dependant on the properties of the substituting R groups, on the triazine ring. Hence, Pa and Pb (R,=,H and OCH3, respectively) showed blue photoluminescent (PL) emission with high quantum yields (QY) even in polar solvents, whereas Pc (R,=,N,N -dimethylamino) gave green-blue PL emission with very low QY. The PL spectra of the polymers in solution were concentration and polarity dependent, which suggested the formation of an exciplex. The three new soluble , -conjugated polymers containing 1,3,5-triazine units in the main chain synthesized here. [source] Hydrogen effects on crystallinity, photoluminescence, and magnetization of indium tin oxide thin films sputter-deposited on glass substrate without heat treatmentPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2010Suning Luo Abstract Indium tin oxide (ITO) thin films were sputter deposited by using working gas containing hydrogen on glass substrate without any heat treatments. The films demonstrated X-ray diffraction due to polycrystalline ITO, blue-green photoluminescence (PL) due to oxygen defects in nano-structured ITO crystals, and paramagnetic behaviour in temperature dependence of magnetization overlapped with diamagnetic signal from the substrate. The carrier density n of the films was of the order of 1020,cm,3, and varied as an inverse of V-character with the hydrogen concentration [H] in the gas. The n value peaked at [H],=,1%. Spectral features at ,430 and ,470,nm of the PL emission were invariant with [H]. The order of the density of electrons N with spins obeying the Curie law was 1023,cm,3, and the variation in N with [H] was almost parallel to that in n with [H]. [source] Structural and photoluminescence studies of erbium-implanted nanocrystalline silicon thin filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2009M. F. Cerqueira Abstract Hydrogenated amorphous and nanocrystalline silicon thin films deposited by hot wire (HW) and radio-frequency plasma-enhanced chemical vapour deposition (RF-PECVD) were erbium-implanted. Their pre-implantation structural properties and post-implantation optical properties were studied and correlated. After 1,h annealing at 150,°C in nitrogen atmosphere only amorphous films showed photoluminescence (PL) activity at 1.54,µm, measured at 5,K. After further annealing at 300,°C for 1,h, all the samples exhibited a sharp PL peak positioned at 1.54,µm, with an FWHM of ,5,nm. Amorphous films deposited by HW originated a stronger PL peak than corresponding films deposited by RF, while in nanocrystalline films PL emission was much stronger in samples deposited by RF than by HW. There was no noticeable difference in Er3+ PL activity between films implanted with 1,×,1014 and 5,×,1015,atoms,cm,2 Er doses. [source] Investigation of InN layers grown by MOCVD using analytical and high resolution TEM: The structure, band gap, role of the buffer layersPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2006P. Ruterana Abstract In this work we investigate the microstructure of InN layers grown by MOCVD on different buffer layers using TEM (InN, GaN). The large mismatch between the various lattices (InN, sapphire or GaN) leads to particular interface structures. Our local analysis allows to show that at atomic scale, the material has the InN lattice parameters and that no metallic In precipitates are present, meaning that the PL emission below 0.8 eV is a genuine property of the InN semiconductor. It is also shown that the N polar layers, which exhibit a 2D growth, have poorer PL emission than In polar layers. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Pressure dependence of photoluminescence spectra of self-assembled InAs/GaAs quantum dotsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2003F.J. Manjón Abstract Photoluminescence (PL) measurements have been performed in InAs/GaAs self-assembled quantum dots (QDs) under high excitation conditions at low temperatures and under high hydrostatic pressures up to 10 GPa. Mechanically polished samples for high pressure experiments exhibited PL emission from the QD ground state but not from the excited states. Instead, a new broad band is observed in the energy range of the first excited state, which is tentatively attributed to emission from smaller dots formed during the mechanical thinning of the sample. With increasing pressure we found a similar blue shift for the PL maxima of the QD ground state (65 meV/GPa) and of the new broad band (69 meV/GPa). These pressure coefficients are 20% and 40% lower than those reported for dots of less than half the height as in our case and for the wetting layer, respectively. Our results point to a systematic reduction of the pressure coefficient of the InAs QDs with the increase of the dot height. [source] Mg-related acceptors in GaNPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7-8 2010B. Monemar Abstract Photoluminescence spectra of c -plane Mg doped GaN samples grown by MOVPE on bulk GaN templates reveal previously unknown properties, like the presence of several Mg-related acceptors. The use of unstrained samples allows a study of both bound exciton (BE) and donor-acceptor pair (DAP) spectra. Two main acceptors A1 and A2 are observed strongly in BE spectra as well as in DAP spectra, they have similar binding energies, i.e. about 220 meV. The common assignment of the deeper blue PL emission at 2.8,3.0 eV to a deep donor-shallow acceptor transition is questioned, and discussed in connection with the compensation problem in p-GaN. It seems like the Fermi level in p-GaN is controlled by a set of Mg-related acceptors at energies 0.2,0.6 eV from the valence band top. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth of A -plane (11-20) In-rich InGaN on R -plane (10-12) sapphire by RF-MBEPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007M. Noda Abstract Non-polar A -plane (11-20) high In content (In-rich) InGaN was grown on R -plane (10-12) sapphire with an InN template by radio-frequency plasma assisted molecular beam epitaxy (RF-MBE). Nitridation of R -plane sapphire was carried out at 300 °C for 2 hours by RF-nitrogen plasma. A template of A -plane InN was grown at 400 °C. The In-rich InGaN films were then grown at the same temperature on the InN template. We characterized the films using reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), scanning electron microscopy (SEM) and photo-luminescence (PL). These results indicated clearly that non-polar In0.71Ga0.29N was successfully obtained with a PL emission at approximately 1.1 eV. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photoluminescence properties of ZnO single crystals with polar and non-polar facesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2006H. Sasaki Abstract Photoluminescence (PL) was circumstantially measured for ZnO single crystals with polar and non-polar faces. PL spectra of ZnO single crystals depended on the sector and polarity of ZnO single crystals. Emissions due to excitons from c -plane substrates sliced from the +c sector were strong, and FWHMs of the emissions were smaller than those from substrates sliced from the ,c sector. An emission due to neutral-donor-bound exicitons (D0X) at 3.361 eV was dominantly observed on all surfaces of ZnO single crystals, and an emission due to ionized-donor-bound excitons (D+X) around 3.366 eV was observed on the O-face but not on the Zn-face at 4.2 K. It is thought that surface state densities due to oxygen caused this difference in PL emission for polarity of ZnO. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effects of Mg fluctuation on the electrical and optical properties in p-GaN/undoped GaN layers dependent on the growth temperaturePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003C. S. Kim Abstract The effects of heavly Mg doping dependent on the growth temperature of p-GaN layers grown on undoped GaN layers by metalorganic chemical vapor deposition (MOCVD) on electrical and optical properties were studied by capacitance,voltage (C,V) and temperature-dependent photoluminescence (TDPL), respectively. At high growth temperature of p-GaN above 1110 °C, optical microscopy images as well as atomic force microscopy (AFM) images show polygonal hillocks on heavily Mg-doped GaN surface. It was also found that fluctuation of Mg concentration ([Mg]) measured by secondary ion mass spectroscopy (SIMS) was increased with increasing growth temperature. These phenomena were appeared to decrease NA,ND and change PL emission from 3.1,3.2 eV of conduction band-to-shallow Mg acceptor (e, A) transition to 2.8,2.9 eV of Mg-related deep donor-to-acceptor pair (DAP) transition. [source] | |||||||||||||