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Xie Yi
Xie Yi FRSC (; born 23 July 1967) is a Chinese chemist. She is a member of the Chinese Academy of Sciences and a fellow of the Royal Society of Chemistry. She is a professor and doctoral supervisor at University of Science and Technology of China. Xie won the L'Oréal-UNESCO Awards for Women in Science in March 2015. Early life and education Xie was born in Fuyang, Anhui on July 23, 1967; her ancestral home is in Anqing, Anhui. She entered Xiamen University in September 1984, majoring in chemistry at the Department of Chemistry, where she graduated in July 1988. After college, she was assigned to a chemical plant in Hefei as an assistant engineer. In September 1992, she was accepted to University of Science and Technology of China, studying chemistry under Qian Yitai, and she earned her doctorate in May 1996. From September 1997 to July 1998, she did postdoctoral work at Stony Brook University. Research and career Xie became a professor at University of Science and Technolog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xie (surname)
Xie (; ) is a Chinese-language surname. lt is usually romanized as "Hsieh" in Taiwan. It is estimated that there are more than ten million people with this surname, the majority of whom live in Taiwan, Southern China, South East Asia, America, Europe and Africa. It is particularly common in Taiwan where it is the 13th most common surname in 2016. It is also very common in the east Asian diaspora which historically tended to have disproportionately emigrated out of southern China. A 2013 study found that Xie was the 23rd most common surname in China, with 0.79% of the population having this surname.Tanghe County and Taikang County of Henan Province: the origin of surname Xie , en.hnta.cn. In 2019 it was again the 23rd most common surname in Mainland China ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanotechnology
Nanotechnology, also shortened to nanotech, is the use of matter on an atomic, molecular, and supramolecular scale for industrial purposes. The earliest, widespread description of nanotechnology referred to the particular technological goal of precisely manipulating atoms and molecules for fabrication of macroscale products, also now referred to as molecular nanotechnology. A more generalized description of nanotechnology was subsequently established by the National Nanotechnology Initiative, which defined nanotechnology as the manipulation of matter with at least one dimension sized from 1 to 100 nanometers (nm). This definition reflects the fact that quantum mechanical effects are important at this quantum-realm scale, and so the definition shifted from a particular technological goal to a research category inclusive of all types of research and technologies that deal with the special properties of matter which occur below the given size threshold. It is therefore common to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoluminescence
Photoluminescence (abbreviated as PL) is light emission from any form of matter after the absorption of photons (electromagnetic radiation). It is one of many forms of luminescence (light emission) and is initiated by photoexcitation (i.e. photons that excite electrons to a higher energy level in an atom), hence the prefix ''photo-''. Following excitation, various relaxation processes typically occur in which other photons are re-radiated. Time periods between absorption and emission may vary: ranging from short femtosecond-regime for emission involving free-carrier plasma in inorganic semiconductorsHayes, G.R.; Deveaud, B. (2002). "Is Luminescence from Quantum Wells Due to Excitons?". ''Physica Status Solidi A'' 190 (3): 637–640doi:10.1002/1521-396X(200204)190:33.0.CO;2-7/ref> up to milliseconds for phosphoresence processes in molecular systems; and under special circumstances delay of emission may even span to minutes or hours. Observation of photoluminescence at a certain ene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanosheet
A nanosheet is a two-dimensional nanostructure with thickness in a scale ranging from 1 to 100 nm. A typical example of a nanosheet is graphene, the thinnest two-dimensional material (0.34 nm) in the world. It consists of a single layer of carbon atoms with hexagonal lattices. Examples and applications , Silicon nanosheets are being used to prototype future generations of small (5 nm) transistors. Carbon nanosheets (from hemp) may be an alternative to graphene as electrodes in supercapacitors. Synthesis The most commonly used nanosheet synthesis methods use a bottom-up approach, e.g., pre-organization and polymerization at interfaces like Langmuir–Blodgett films, solution phase synthesis and chemical vapor deposition (CVD). For example, CdTe ( cadmium telluride) nanosheets could be synthesized by precipitating and aging CdTe nanoparticles in deionized water. The formation of free-floating CdTe nanosheets was due to directional hydrophobic attraction and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrocatalyst
An electrocatalyst is a catalyst that participates in electrochemical reactions. Electrocatalysts are a specific form of catalysts that function at electrode surfaces or, most commonly, may be the electrode surface itself. An electrocatalyst can be heterogeneous such as a platinized electrode. Homogeneous electrocatalysts, which are soluble, assist in transferring electrons between the electrode and reactants, and/or facilitate an intermediate chemical transformation described by an overall half reaction. Major challenges in electrocatalysts focus on fuel cells. Practical electrocatalysts Chloralkali process The chloralkali process is a large scale application that uses electrocatalysts. This technology supplies most of the chlorine and sodium hydroxide required by many industries. The cathode is a mixed metal oxide clad titanium anode (also called a dimensionally stable anode). Electrofluorination Many organofluorine compounds are produced by electrofluorination. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrochemical Capacitor
A supercapacitor (SC), also called an ultracapacitor, is a high-capacity capacitor, with a capacitance value much higher than other capacitors but with lower voltage limits. It bridges the gap between electrolytic capacitors and rechargeable batteries. It typically stores 10 to 100 times more energy per unit volume or mass than electrolytic capacitors, can accept and deliver charge much faster than batteries, and tolerates many more charge and discharge cycles than rechargeable batteries. Supercapacitors are used in applications requiring many rapid charge/discharge cycles, rather than long-term compact energy storage — in automobiles, buses, trains, cranes and elevators, where they are used for regenerative braking, short-term energy storage, or burst-mode power delivery. Smaller units are used as power backup for static random-access memory (SRAM). Unlike ordinary capacitors, supercapacitors do not use the conventional solid dielectric, but rather, they use electros ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stoichiometric
Stoichiometry refers to the relationship between the quantities of reactants and products before, during, and following chemical reactions. Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equals the total mass of the products, leading to the insight that the relations among quantities of reactants and products typically form a ratio of positive integers. This means that if the amounts of the separate reactants are known, then the amount of the product can be calculated. Conversely, if one reactant has a known quantity and the quantity of the products can be empirically determined, then the amount of the other reactants can also be calculated. This is illustrated in the image here, where the balanced equation is: : Here, one molecule of methane reacts with two molecules of oxygen gas to yield one molecule of carbon dioxide and two molecules of water. This particular chemical equation is an example of complete combustion. St ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fourier-transform Infrared Spectroscopy
Fourier-transform infrared spectroscopy (FTIR) is a technique used to obtain an infrared spectrum of absorption or emission of a solid, liquid, or gas. An FTIR spectrometer simultaneously collects high-resolution spectral data over a wide spectral range. This confers a significant advantage over a dispersive spectrometer, which measures intensity over a narrow range of wavelengths at a time. The term ''Fourier-transform infrared spectroscopy'' originates from the fact that a Fourier transform (a mathematical process) is required to convert the raw data into the actual spectrum. Conceptual introduction The goal of absorption spectroscopy techniques (FTIR, ultraviolet-visible ("UV-vis") spectroscopy, etc.) is to measure how much light a sample absorbs at each wavelength. The most straightforward way to do this, the "dispersive spectroscopy" technique, is to shine a monochromatic light beam at a sample, measure how much of the light is absorbed, and repeat for each different ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-resolution Transmission Electron Microscopy
High-resolution transmission electron microscopy is an imaging mode of specialized transmission electron microscopes that allows for direct imaging of the atomic structure of samples. It is a powerful tool to study properties of materials on the atomic scale, such as semiconductors, metals, nanoparticles and sp2-bonded carbon (e.g., graphene, C nanotubes). While this term is often also used to refer to high resolution scanning transmission electron microscopy, mostly in high angle annular dark field mode, this article describes mainly the imaging of an object by recording the two-dimensional spatial wave amplitude distribution in the image plane, in analogy to a "classic" light microscope. For disambiguation, the technique is also often referred to as phase contrast transmission electron microscopy. At present, the highest point resolution realised in phase contrast transmission electron microscopy is around . At these small scales, individual atoms of a crystal and its defects can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field-emission Microscopy
Field-emission microscopy (FEM) is an analytical technique used in materials science to investigate molecular surface structures and their electronic properties. Invented by Erwin Wilhelm Müller in 1936, the FEM was one of the first surface-analysis instruments that approached near-atomic resolution. Introduction Microscopy techniques are used to produce real-space magnified images of a surface showing what it looks like. In general, microscopy information concerns surface crystallography (i.e. how the atoms are arranged at the surface), surface morphology (i.e. the shape and size of topographic features making the surface), and surface composition (the elements and compounds the surface is composed of). Field-emission microscopy (FEM) was invented by Erwin Müller in 1936. In FEM, the phenomenon of field electron emission was used to obtain an image on the detector on the basis of the difference in work function of the various crystallographic planes on the surface. Design A f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Crystallography
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their crystallographic disorder, and various other information. Since many materials can form crystals—such as salts, metals, minerals, semiconductors, as well as various inorganic, organic, and biological molecules—X-ray crystallography has been fundamental in the development of many scientific fields. In its first decades of use, this method determined the size of atoms, the lengths and types of chemical bonds, and the atomic-scale differences among various mat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annular Dark-field Imaging
Annular dark-field imaging is a method of mapping samples in a scanning transmission electron microscope (STEM). These images are formed by collecting scattered electrons with an annular dark-field detector. Conventional TEM dark-field imaging uses an objective aperture in order to only collect scattered electrons that pass through. In contrast, STEM dark-field imaging does not use an aperture to differentiate the scattered electrons from the main beam, but uses an annular detector to collect only the scattered electrons. Consequently, the contrast mechanisms are different between conventional dark field imaging and STEM dark field. An annular dark field detector collects electrons from an annulus around the beam, sampling far more scattered electrons than can pass through an objective aperture. This gives an advantage in terms of signal collection efficiency and allows the main beam to pass to an electron energy loss spectroscopy (EELS) detector, allowing both types of mea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
