George R. Fern

Effects of the host lattice and doping concentration on the colour of Tb3+ cation emission in Y2O2S:Tb3+ and Gd2O2S:Tb3+ nanometer sized phosphor particles

Y2O2S and Gd2O2S phosphor lattices activated with a range of Tb(3+) concentrations have been successfully prepared as nanoparticles and their emission properties have been characterized using SEM, XRPD, photoluminescence spectroscopy and cathodoluminescence. (5)D3-(5)D4 cross relaxation processes between Tb(3+) cations were observed in both Y2O2S and Gd2O2S as a function of Tb(3+) concentration. In the Y2O2S host lattice, the predominant emission colour shifts from blue to green with increased Tb(3+) concentration. In contrast, green emission is always predominant in Gd2O2S at Tb(3+) concentrations from 0.1 mol% to 5 mol%. This finding is explained in accordance with previous reports on the bulk materials that found the Gd2O2S lattice has a lower charge transfer state than the Y2O2S host lattice.

Surface plasmon resonance imaging detection of silver nanoparticle-tagged immunoglobulin

The detection sensitivity of silver nanoparticle (AgNP)-tagged goat immunoglobulin G (gIgG) microarrays was investigated by studying surface plasmon resonance (SPR) images captured in the visible wavelength range with the help of a Kretchmann-configured optical coupling set-up. The functionalization of anti-gIgG molecules on the AgNP surface was studied using transmission electron microscopy, photon correlation measurements and UV–visible absorption spectroscopy. A value of 1.3 × 107 M−1 was obtained for the antibody–antigen binding constant by monitoring the binding events at a particular resonance wavelength. The detection limit of this SPR imaging instrument is 6.66 nM of gIgG achieved through signal enhancement by a factor of larger than 4 owing to nanoparticle tagging with the antibody.

Effects of the nature of the nitrogen donor atom (sp2versus sp3) upon the properties and chemistry of palladated complexes with σ(Pd–Csp2, ferrocene) bonds

The NMR and Mossbauer spectra and electrochemistry of the N-donor ferrocenyl ligands [Fe(η5-C5H5){(η5-C5H4CHNCH2Ph)}] and [Fe(η5-C5H5)(η5-C5H4CH2NMe2)] as well as their mononuclear derivatives with σ(Pd–Csp2, ferrocene) bonds [[graphic omitted]CH2Ph)}Cl(L)], [[graphic omitted]Me2)}Cl(L)][L = 1 -methylimidazole (mim) or PPh3], and [Pd{(η5-C5H5)Fe(η5-C5H3CH2NMe2)}Cl(PPh3)2] have been studied. Comparison of the data allows an understanding of the influence of the nature of the N-donor atom of the ferrocenyl moiety (sp2versus sp3) upon the properties of these compounds. In particular, the differences observed in the quadrupole splitting parameters obtained from Mossbauer spectroscopy reveal not only that the palladium(II) acts as an electron-withdrawing group in all these cyclometallated derivatives, but also that most of the electron density is withdrawn from the imine CHN moiety in the derivatives containing ferrocenyl Schiff bases as ligands. The crystal structures of [[graphic omitted]CH2Ph)}Cl(PPh3)] and [[graphic omitted]Me2)}Cl(mim)] have been determined.

Alkyne insertions into the σ-Pd–C(sp2, ferrocene) bond of cyclopalladated complexes containing Schiff bases derived from ferrocene. Crystal structures of [Pd{[(EtCCEt)2(η5-C5H3CRNCH2Ph)]Fe(η5-C5H5)}Cl](R = H or Me)

Reactions of di-µ-chloro-bridged cyclopalladated compounds [{[graphic omitted]R′)Fe(η5-C5H5)](µ-Cl)}2](R = H, Ph or Me, R′= CH2Ph; R = H, R′= CH2CH2Ph) with alkynes R″CCR″(R″= Et or Ph) have been studied. In all cases these reactions produce nine-membered metallocycles [[graphic omitted]R′)]Fe(η5-C5H5)}Cl](R″= Et or Ph), which arise from a double insertion of the alkyne. Compounds [[graphic omitted]CH2Ph)]Fe(η5-C5H5)}Cl](R = H 4a or Me 4d) have been characterized structurally. Complex 4a is monoclinic, space group C2/c, with a= 30.783(4), b= 11.320(2), c= 20.181(3)A and β= 127.23(3)°; compound 4d is also monoclinic space group P21/a, with a= 20.308(4), b= 11.075(2), c= 12.565(2)A and β= 92.01(3)°. These structural studies confirm the existence of a bicyclic system arising from the fusion of a nine-membered ring and the C5H3 moiety of the ferrocenyl moiety. The differences observed in the reactivity of the σ(Pd–Csp2, ferrocene) bond in the cyclopalladated compounds [{[graphic omitted]R′)Fe(η5-C5H5)](µ-Cl)}2](R = H, Ph or Me) and in [{[graphic omitted]Me2}Fe(η5-C5H5)](µ-Cl)}2] can be explained in terms of the electron donor ability of the chelated ligand. This property is reflected mainly in the redox potential of the iron centre.

A Synthetic Method for the Production of a Range of Particle Sizes for Y 2 O 3 : Eu Phosphors Using a Copolymer Microgel of NIPAM and AMPS

A novel method for preparing the cathodoluminescent red europium-doped yttrium oxide (Y 2 O 3 :Eu) phosphor using the copolymer microgel of N-isopropylacrylamide (NIPAM) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) is described. An extensive range of spherical particle sizes can be produced by careful manipulation of the experimental conditions. Spherical particle size is shown to be directly controlled by the quantities of copolymer microgel, allowing spherical particles for a given size from 0.1 to 1.3 μm to be produced. The luminescent intensity of the particles related to the particle size is also reported.

Structure and Morphology of ACEL ZnS:Cu,Cl Phosphor Powder Etched by Hydrochloric Acid

© The Electrochemical Society, Inc. 2009. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version is available at the link below.

Synthesis and characterization of a new (phthalocyani-nato)bis(carboxylate) silicon(IV) compound with increased solubility

The synthesis and spectroscopic characterization of a new soluble silicon(IV) phthalocyanine complex is presented. The compound shows an increased solubility compared to its SiPcCl2 precursor and this allowed solution 1H NMR characterization. The assignment of the 1H NMR signals for the axial ligands is greatly facilitated due to the anisotropic high ring current effects from the macrocycle. In addition, good quality crystals were grown from this more soluble material for molecular structure determination by single-crystal X-ray diffraction analysis. The molecular structure determination shows that the complex crystallizes in a non-centrosymmetric space group due to the inherent chirality of the naproxene ligands. Bond lengths and angles fit well to other analogous compounds previously reported.

Ultraviolet and blue cathodoluminescence from cubic Y2O3 and Y2O3: Eu3+ generated in a transmission electron microscope

The EPSRC and the Technology Strategy Board (TSB) funded the PURPOSE (TP11/MFE/6/I/AA129F; EPSRC TS/G000271/1), CONVERTED (JeS no. TS/1003053/1) and PRISM (EP/N508974/1) programs. The TSB for funding the CONVERT program.

Contrast and decay of cathodoluminescence from phosphor particles in a scanning electron microscope

Cathodoluminescence (CL) studies are reported on phosphors in a field emission scanning electron microscope (FESEM). ZnO: Zn and other luminescent powders manifest a bright ring around the periphery of the particles: this ring enhances the contrast. Additionally, particles resting on top of others are substantially brighter than underlying ones. These phenomena are explained in terms of the combined effects of electrons backscattered out of the particles, together with light absorption by the substrate. The contrast is found to be a function of the particle size and the energy of the primary electrons. Some phosphor materials exhibit a pronounced comet-like structure at high scan rates in a CL-image, because the particle continues to emit light after the electron beam has moved to a position without phosphor material. Image analysis has been used to study the loss of brightness along the tail and hence to determine the decay time of the materials. The effect of phosphor saturation on the determination of decay times by CL-microscopy was also investigated.

42.4: Low Cost, Flexible Electroluminescent Displays with a Novel Electrode Architecture Printed by Offset Lithography

We report flexible, multi-colored electroluminescent displays that are produced using offset lithographic printing of interdigitated electrodes. These displays can be mass produced at low cost as they require no transparent conducting oxides as anode. Applications include back-lighting, large-scale low-cost lighting displays, and low-resolution display technology.