amorphous selenium red

Selenium Structure of Amorphous Selenium by 2D 77Se NMR Spectroscopy: An End to the Dilemma of Chain versus Ring Maxwell Marple, Jackson Badger, Ivan Hung, Zhehong Gan, Kirill Kovnir,* and Sabyasachi Sen* Abstract: Amorphous selenium, owing to its tremendous technological importance and perhaps to its chemical simplicity, has been studied for ...

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Amorphous selenium flat panel detectors for medical applications. ... edge found to be red‐shifted along with a sharp decrease in optical band gap (1.74‐0.82), with the increasing fraction of ...

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The adsorption behavior of 197 Hg and 183–185 Hg on red amorphous selenium (red a-Se) and trigonal selenium (t-Se) was investigated experimentally by off-line and on-line gas chromatographic methods, in preparation of a sensitive chemical separation and characterization of the transactinides copernicium (Cn, Z = 112) and flerovium (Fl, Z = 114).

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The end products of these reactions are the red, amorphous or monoclinic allotropes of Se(0), which accumulate in spent medium because the microorganisms reduce the 10 to 20 mM selenate or selenite provided to Se(0). Respiratory reductases for Se oxyanions contain molybdenum and are associated with the plasma membrane .

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Selenium is a non metallic chemical element exists in several allotropic forms, although three are generally recognized. In chemical activity and physical properties it resembles sulfur and tellurium. It can be prepared with either an amorphous or a crystalline structure. The color of amorphous selenium is either red (in powder form) or black (in vitreous form).

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Amorphous selenium is either red, in powder form, or black, in vitreous, or glassy, form. The most stable form of the element, crystalline hexagonal selenium, is a metallic gray, while crystalline ...

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Selenium forms several allotropes that interconvert with temperature changes, depending somewhat on the rate of temperature change. When prepared in chemical reactions, selenium is usually an amorphous, brick-red powder.When rapidly melted, it forms the black, vitreous form, usually sold commercially as beads. The structure of black selenium is irregular and complex and consists of …

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Amorphous selenium (a-Se) is a promising material for a high-sensitivity photodetector that has low thermal noise and a wide detectable wavelength range that covers visible to the UV, …

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types of selenium-containing particles. Different bacteria are known to convert selenium oxyanions into red amorphous SeNPs with distinct features. Selenium NPs produced by the selenium-respiring bacteria Sulfurospirillum barnesii and Bacillus selenitireducens contain predominantly Se 6 chain units, while Selenihalanaerobacter shriftii has Se 8 ...

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Amorphous selenium is either a reddish powder or a black, vitreous solid; crystalline selenium is either red or gray, depending on the crystal structure. This element resembles sulfur in its various forms and in its compounds. Selenium has many electrical properties, being both photovoltaic, where light converts to electricity, and ...

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Amorphous Selenium (a-Se) Many of the detector systems being developed in our lab use a photoconductor called amorphous Selenium (a-Se) as the X-ray detector material, i.e. the material which 'catches the X-rays', and converts them to either charge or lower energy photons.

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May 04, 1976· Red amorphous selenium is obtained by precipitating selenium from a solution of selenious acid in methanol or ethanol with hydrazine or a soluble salt thereof at a temperature between about -20°C. and the freezing point of the solution.

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amorphous selenium, which exists in black and red forms. Black amorphous selenium is vitreous and is formed by the rapid cooling of liquid selenium. Red amorphous selenium is colloidal and is formed in reduction reactions (Hoffmann and King 1997). Important selenium oxidation states are -2, 0, +4, and +6.

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May 12, 2013· I talk about selenium and show selenium transitioning from its black, metallic form to its red, amorphous form and back again!

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Jun 08, 2001· The best fit of (αhν) 1/n versus the photon energy, in the case of both amorphous and hexagonal selenium thin films, was obtained for n= 1 2. The extrapolation of the linear part gave band gap energy of 2.0 eV for the amorphous, red selenium thin films, while for gray ones it …

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Selenium can be prepared with either an amorphous or a crystalline structure. The color of amorphous selenium is either red (in powder form) or black (in vitreous form). Crystalline monoclinic selenium is a deep red; crystalline hexagonal selenium, the most stable variety, is a metallic gray.

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The selenium starting material is reduced to selenium, and precipitates as a red amorphous solid which can easily be filtered off. This type of reaction is called a Riley oxidation. It is also renowned as a reagent for "allylic" oxidation, a reaction that entails the following conversion

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Phosphorus, red ≥99.99% trace metals basis CAS Number 7723-14-0. Empirical Formula (Hill Notation) P . Molecular Weight 30.97 . EC Number 231-768-7. MDL number MFCD00133771. PubChem Substance ID 24861136

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Selenium forms several allotropes that interconvert with temperature changes, depending somewhat on the rate of temperature change. When prepared in chemical reactions, selenium is usually an amorphous, brick-red powder. When rapidly melted, it forms the black, vitreous form, usually sold commercially as beads.

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Grey crysstalline selenium Grey selenium in glass sphere. Crystals of gray Selenium. Granules of amorphous selenium (4N) Ingot of amorphous selenium (99.5+%) Ingot of glassy selenium. Red selenium. Selenium rectifiers. Directionally solidified grey Selenium. Monoclinic Selenium crystals. Has dark red color in transmitting light.

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INTRODUCTION THE STRUCTURE of red amorphous selenium and its transformations are not well known. Mondain-Monvaltl] and Richter et al.[2] assumed that red amorphous and vitreous selenium which has been subject to many investigations [3,4] differ from each other only …

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The absorption coefficient of amorphous selenium has been measured in the ultra-violet, visible and near infra-red spectral regions. The transmission coefficients of several single crystals of selenium have been measured and an estimate made of the absorption coefficient in the wavelength range 0.68 to 2.0 μ.

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Red amorphous selenium is obtained by precipitating selenium from a solution of selenious acid in methanol or ethanol with hydrazine or a soluble salt thereof at a temperature between about -20°C. and the freezing point of the solution. read more. 08 Dec, 2019.

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Measurements have been made of the refractive index of amorphous selenium in the red and near infra-red spectral region. The absorption coefficient of amorphous selenium has been measured in the ...

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INTRODUCTION THE STRUCTURE of red amorphous selenium and its transformations are not well known. Mondain-Monvaltl] and Richter et al.[2] assumed that red amorphous and vitreous selenium which has been subject to many investigations [3,4] differ from each other only …

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A flat panel x-ray imager exhibiting reduced ghosting effects and overvoltage protection by appropriate leakage current characteristics of the thin-film transistor array. A top electrode of a suitable material is directly on and in physical and electrical contact with an amorphous selenium-based charge generator layer, thereby reducing ghosting.

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Among the various morphologies of elemental Se, recent studies reported red amorphous selenium (red a-Se) to be the best sorbent for mercury vapor, partly due to the high surface-to-mass ratios of ...

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Selenium is applied as the cathode material of lithium/selenium (Li–Se) battery, which has high theoretical volumetric capacity density (3253 mA h·cm–3) and high output voltages. However, it has a low melting point (494 K) and a large sensitivity to thermal treatment, which often result in the phase transition between crystalline Se (trigonal phase) and amorphous Se during the charge ...

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mainly composed of red amorphous selenium, was not stable in the presence of the dithionite decomposition by-products and partially redissolved after several hours. In the case of the reaction involving selenious acid and sulfide ions, the results showed that,

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Selenium (Redirected from Seleniun) Read in another language Watch this page Edit ...

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