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Stokes Shift
__NOTOC__ Stokes shift is the difference (in energy, wavenumber or frequency units) between positions of the band maxima of the absorption and emission spectra (fluorescence and Raman being two examples) of the same electronic transition. It is named after Irish physicist George Gabriel Stokes. Sometimes Stokes shifts are given in wavelength units, but this is less meaningful than energy, wavenumber or frequency units because it depends on the absorption wavelength. For instance, a 50 nm Stokes shift from absorption at 300 nm is larger in terms of energy than a 50 nm Stokes shift from absorption at 600 nm. When a system (be it a molecule or atom) absorbs a photon, it gains energy and enters an excited state. One way for the system to relax is to emit a photon, thus losing its energy (another method would be the loss of energy as translational mode energy (via vibrational-translational or electronic-translational collisional processes with other atoms or molecules)). When the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stokes Shift- Rh6G
Stokes may refer to: People * Stokes (surname), a surname (including a list of people with the name) Science * Stokes (unit), a measure of viscosity * Stokes boundary layer * Stokes drift * Stokes flow * Stokes' law * Stokes' law of sound attenuation * Stokes line * Stokes number * Stokes parameters * Stokes radius * Stokes relations * Stokes shift * Stokes stream function * Stokes' theorem * Stokes wave * Campbell–Stokes recorder * Navier–Stokes equations Places Australia * Stokes, Queensland, a locality in the Shire of Carpentaria, Queensland, Australia * Stokes Bay (South Australia), a bay in South Australia * Stokes Bay, South Australia, a locality in South Australia * Stokes National Park, in the Goldfields-Esperance region of Western Australia Canada * Stokes Mountain, a mountain in Nunavut, Canada * Stokes Range, a mountain range in Nunavut, Canada New Zealand * Stokes Valley, a suburb of Lower Hutt in New Zealand ** Stokes Valley RFC, a rugby football ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Excited State
In quantum mechanics, an excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum). Excitation refers to an increase in energy level above a chosen starting point, usually the ground state, but sometimes an already excited state. The temperature of a group of particles is indicative of the level of excitation (with the notable exception of systems that exhibit negative temperature). The lifetime of a system in an excited state is usually short: spontaneous or induced emission of a quantum of energy (such as a photon or a phonon) usually occurs shortly after the system is promoted to the excited state, returning the system to a state with lower energy (a less excited state or the ground state). This return to a lower energy level is often loosely described as decay and is the inverse of excitation. Long-lived excited states are often called ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jablonski Diagram
Jabłoński (Polish pronunciation: ; feminine: Jabłońska; plural: Jabłońscy) is a Polish surname derived from the noun ''jabłoń'' (''apple tree''). It appears in various forms when transliterated from Cyrillic alphabets. People * Aleksander Jabłoński (1898–1980), Polish physicist * Benedict Jablonski (1917–2003), science fiction fan and booster * Carl Gustav Jablonsky (1756–1787), Berlin naturalist, entomologist and illustrator * Constance Jablonski (born 1990), French fashion model * Daniel Ernst Jablonski (1660–1741), German theologian and reformer * Dariusz Jabłoński (born 1961), Polish film director and producer * David Jablonski (born 1953), American professor of geophysical sciences * Edward Jablonski (1923–2004), American author * Edward Jabłoński (1919–1970), Polish football player * Grigoriy Yablonsky (born 1940), Russian chemist * Hanna Yablonska (1981–2011), Ukrainian playwright and poet * Henryk Jabłoński (1909–2003), Polish socialist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upconverting Nanoparticles
Upconverting nanoparticles (UCNPs) are nanoscale particles (diameter 1–100 nm) that exhibit photon upconversion. In photon upconversion, two or more incident photons of relatively low energy are absorbed and converted into one emitted photon with higher energy. Generally, absorption occurs in the infrared, while emission occurs in the visible or ultraviolet regions of the electromagnetic spectrum. UCNPs are usually composed of rare-earth based lanthanide- or actinide-doped transition metals and are of particular interest for their applications in ''in vivo'' bio-imaging, bio-sensing, and nanomedicine because of their highly efficient cellular uptake and high optical penetrating power with little background noise in the deep tissue level. They also have potential applications in photovoltaics and security, such as infrared detection of hazardous materials. Before 1959, the anti-Stokes shift was believed to describe all situations in which emitted photons have higher energies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photon Upconversion
A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, so they always move at the speed of light in vacuum, (or about ). The photon belongs to the class of bosons. As with other elementary particles, photons are best explained by quantum mechanics and exhibit wave–particle duality, their behavior featuring properties of both waves and particles. The modern photon concept originated during the first two decades of the 20th century with the work of Albert Einstein, who built upon the research of Max Planck. While trying to explain how matter and electromagnetic radiation could be in thermal equilibrium with one another, Planck proposed that the energy stored within a material object should be regarded as composed of an integer number of discrete, equal-sized parts. To explain the photoelectric effect, Einste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gadolinium Oxysulfide
Gadolinium oxysulfide ( Gd2 O2 S), also called gadolinium sulfoxylate, GOS or Gadox, is an inorganic compound, a mixed oxide-sulfide of gadolinium. Uses The main use of gadolinium oxysulfide is in ceramic scintillators. Scintillators are used in radiation detectors for medical diagnostics. The scintillator is the primary radiation sensor that emits light when struck by high energy photons. Gd2O2S based ceramics exhibit final densities of 99.7% to 99.99% of the theoretical density (7.32 g/cm3) and an average grain size ranging from 5 micrometers to 50 micrometers in dependence with the fabrication procedure. Two powder preparation routes have been successful for synthesizing Gd2O2S: Pr, Ce, F powder complexes for the ceramic scintillators. These preparations routes are called the halide flux method and the sulfite precipitation method. The scintillation properties of Gd2O2S: Pr, Ce, F complexes demonstrate that this scintillator is promising for imaging applications. There ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yttrium
Yttrium is a chemical element with the symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost always found in combination with lanthanide elements in rare-earth minerals, and is never found in nature as a free element. 89Y is the only stable isotope, and the only isotope found in the Earth's crust. The most important uses of yttrium are LEDs and phosphors, particularly the red phosphors in television set cathode ray tube displays. Yttrium is also used in the production of electrodes, electrolytes, electronic filters, lasers, superconductors, various medical applications, and tracing various materials to enhance their properties. Yttrium has no known biological role. Exposure to yttrium compounds can cause lung disease in humans. The element is named after '' ytterbite'', a mineral first identified in 1787 by the chemist Carl Axel Arrhenius. He n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2D Materials (journal)
''2D Materials '' is a peer-reviewed scientific journal published by IOP Publishing. It is devoted to publishing fundamental and applied research of the highest quality and impact covering all aspects of graphene and related Single-layer materials, two-dimensional materials. The editor-in-chief is Wencai Ren (Chinese Academy of Sciences). Scope ''2D Materials'' publishes letters, research papers, perspectives, topical reviews, focus issues, and roadmaps across a given subject area. Specific materials of interest will include, but are not limited to: *Graphene and graphene-derived materials *Silicene and germanene/silicane and germanane *Boron nitride *Transition metal dichalcogenides *Two-dimensional topological insulators *Complex oxides *Composite materials *Other novel two-dimensional layered structures Abstracting and indexing According to the ''Journal Citation Reports'', the journal had a 2021 impact factor of 6.861. It is indexed in the following bibliographic databases ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambridge University Press
Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by Henry VIII of England, King Henry VIII in 1534, it is the oldest university press A university press is an academic publishing house specializing in monographs and scholarly journals. Most are nonprofit organizations and an integral component of a large research university. They publish work that has been reviewed by schola ... in the world. It is also the King's Printer. Cambridge University Press is a department of the University of Cambridge and is both an academic and educational publisher. It became part of Cambridge University Press & Assessment, following a merger with Cambridge Assessment in 2021. With a global sales presence, publishing hubs, and offices in more than 40 Country, countries, it publishes over 50,000 titles by authors from over 100 countries. Its publishing includes more than 380 academic journals, monographs, reference works, school and uni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Atkins
Peter William Atkins (born 10 August 1940) is an English chemist and a Fellow of Lincoln College at the University of Oxford. He retired in 2007. He is a prolific writer of popular chemistry textbooks, including ''Physical Chemistry'', ''Inorganic Chemistry'', and ''Molecular Quantum Mechanics''. Atkins is also the author of a number of popular science books, including ''Atkins' Molecules'', ''Galileo's Finger: The Ten Great Ideas of Science'' and ''On Being''. Career Atkins left school (Dr Challoner's Grammar School, Amersham) at fifteen and took a job at Monsanto as a laboratory assistant. He studied for A-levels by himself and gained a place, following a last-minute interview, at the University of Leicester. Atkins studied chemistry there, obtaining a BSc degree in chemistry, and a PhD degree in 1964 for research into electron spin resonance spectroscopy, and other aspects of theoretical chemistry. Atkins then took a postdoctoral position at UCLA as a Harkness Fellow of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dipole
In physics, a dipole () is an electromagnetic phenomenon which occurs in two ways: *An electric dipole deals with the separation of the positive and negative electric charges found in any electromagnetic system. A simple example of this system is a pair of charges of equal magnitude but opposite sign separated by some typically small distance. (A permanent electric dipole is called an electret.) *A magnetic dipole is the closed circulation of an electric current system. A simple example is a single loop of wire with constant current through it. A bar magnet is an example of a magnet with a permanent magnetic dipole moment. Dipoles, whether electric or magnetic, can be characterized by their dipole moment, a vector quantity. For the simple electric dipole, the electric dipole moment points from the negative charge towards the positive charge, and has a magnitude equal to the strength of each charge times the separation between the charges. (To be precise: for the definition of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
