Luminescent Functional Metal–Organic Frameworks

Fluorescent carbon nanoparticles or carbon quantum dots (CQDs) are a new class of carbon nanomaterials that have emerged recently and have garnered much interest as potential competitors to conventional semiconductor quantum dots. In addition to their comparable optical properties, CQDs have the desired advantages of low toxicity, environmental friendliness low cost and simple synthetic routes. Moreover, surface passivation and functionalization of CQDs allow for the control of their physicochemical properties. Since their discovery, CQDs have found many applications in the fields of chemical sensing, biosensing, bioimaging, nanomedicine, photocatalysis and electrocatalysis. This article reviews the progress in the research and development of CQDs with an emphasis on their synthesis, functionalization and technical applications along with some discussion on challenges and perspectives in this exciting and promising field.

Carbon quantum dots and their applications

Recent startling interest for lanthanide luminescence is stimulated by the continuously expanding need for luminescent materials meeting the stringent requirements of telecommunication, lighting, electroluminescent devices, (bio-)analytical sensors and bio-imaging set-ups. This critical review describes the latest developments in (i) the sensitization of near-infrared luminescence, (ii) “soft” luminescent materials (liquid crystals, ionic liquids, ionogels), (iii) electroluminescent materials for organic light emitting diodes, with emphasis on white light generation, and (iv) applications in luminescent bio-sensing and bio-imaging based on time-resolved detection and multiphoton excitation (500 references).

/pdf/lanthanide-luminescence-for-functional-materials-and-bio-1w9cppwf8r.pdf

Lanthanide luminescence for functional materials and bio-sciences

Lanthanide-based luminescent hybrid materials.

There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Handbook of Chemistry and Physics

We report on the variation of the absorption coefficient αf with wave number W, for Cl‐doped n‐type (94×1016–8×1018 cm−3) ZnSe epitaxial films grown on GaAs Below the classical mid‐infrared range of W, αf has large values (16×103–211×104 cm−1) appropriate for thin‐film measurements, with αf proportional to W−p Large variations of αf and p occur as a function of the free‐electron concentration The results are compared to a recent theoretical model by Ruda [J Appl Phys 61, 3035 (1987)], which is specific to ZnSe

Infrared absorption in n-type znse/gaas heteroepitaxial films

A novel three dimensional (3D) self-assembled hierarchical bismuth oxide was prepared via a sol-gel synthesis with the aid of capping agent of polyethylene glycol-8000 (PEG-8000) at 85 ℃ in 45 min. The morphology evolution was studied versus reaction time and interpreted in terms of growth mechanisms. The as-grown 3D hierarchical flower-like bismuth oxide was crystalline cubic gamma-phase. The morphology and crystal phase of these 3D cubic gamma-phase bismuth oxide flowers were not changed with heating up to 600 ℃. The flower-like morphology was attributed to modification of the growth kinetics by the capping agent from the PEG-OH bond bridging with bismuth ions. Europium doped gadolinium oxide shell were further deposited on the bismuth oxide cores through sol-gel synthesis showing good photoluminescence characteristics at 610 and 622 nm under the excitation at 280 nm.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1946427400016328

Core/Shell Composite of Self-Assembled Hierarchical Bismuth Oxide/Europium Doped Gadolinium Oxide for Scintillating Detection

This paper reviews the analysis of exterior leakage paths causing failures of common 2N2222A transistors. The failure mechanism, exterior leakage paths activated in high humidity conditions on the surface of glass seals, is identified. The glass constituents which are responsible for this intermittent, sometime self-correcting failure mechanism are discussed and the method of conduction analyzed.

Humidity Activated Surface Leakage Paths on T.O. Case Style Glass Headers

Europium-activated yttrium oxide (Eu:Y2O3) thin films were deposited on (100) silicon and (0001) sapphire substrates using 248 nm KrF pulsed laser. To investigate the effect of the Eu:Y2O3 film roughness on cathodoluminescence (CL) and photoluminescence (PL) properties, the substrate surfaces with various roughnesses were used. The roughness was found to play an important role in determining CL and PL brightness of the Eu:Y2O3 films. The improvement in brightness by increasing the film roughness is due to increase in total portion of light that escapes from the surface of the phosphor film. A model has been proposed which supports strongly this explanation. Our results show that depositions with slower growth rate and lower laser energy are more important parameters than increasing the roughness to improve CL brightness of the Eu:Y2O3 thin film phosphors.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S194642740020777X

Modeling of Cathodoluminescence and Photoluminescence Properties of Pulsed Laser-Deposited Europium-Activated Yttrium Oxide Thin Film Phosphors

Scintillating nanoparticles with a SiO 2 core and a Gd 2 O 3 shell doped with Eu 3+ were synthesized with a sol-gel process. Based on transmission electron microscopy (TEM) data, a ∼13 nm Gd 2 O 3 shell was successfully coated onto ∼220 nm mono-dispersed SiO 2 nanocores. Eu 3+ ions at concentrations of nominally 5 at% exhibited photoluminescent (PL) emission from the SiO 2 /Gd 2 O 3 nanoparticles after being calcined at 800 0 C for 2 h. The SiO 2 remained amorphous after calcining, while the Gd 2 O 3 crystallized to a cubic structure. The PL emission was from the 5 D 0 - 7 F 2 transitions of Eu 3+ at 609 and 622 nm. Photoluminescence excitation (PLE) data showed that emission from Eu 3+ could result from direct excitation, but was dominated by the oxygen to europium charge-transfer band (CTB) between 250 and 280 nm for Eu 3+ doped in Gd 2 O 3 . The quantum yield (QY) from thin films drop cast from a mixture of 20 mg of calcined nanoparticles in 500 μL of polymethylmethacrylate (PMMA) and excited in the CTB was 20% for SiO 2 /Gd 2 O 3 :Eu 3+ core/shell scintillation nanoparticles. Finally, the above core/shell nanoparticles were passivated with a shell of SiO 2 to create e.g. SiO 2 /Gd 2 O 3 :Eu 3+ /SiO 2 nanoparticles. The QYs for this nanostructure were lower than unpassivated nanoparticles which was attributed to a weak CTB for the amorphous SiO 2 shell and a higher density of interface quenching sites.

Paul H. Holloway

Papers

Infrared absorption in n-type znse/gaas heteroepitaxial films

Core/Shell Composite of Self-Assembled Hierarchical Bismuth Oxide/Europium Doped Gadolinium Oxide for Scintillating Detection

Humidity Activated Surface Leakage Paths on T.O. Case Style Glass Headers

Modeling of Cathodoluminescence and Photoluminescence Properties of Pulsed Laser-Deposited Europium-Activated Yttrium Oxide Thin Film Phosphors

Structure and Luminescence of Europium-Doped Gadolinia-Based Core/Multi-Shell Scintillation Nanoparticles