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In chemistry, quenching refers to any process which decreases the fluorescent intensity of a given substance. A variety of processes can result in quenching, such as excited state reactions, energy transfer, complex-formation and collisions. As a consequence, quenching is often heavily dependent on pressure and temperature.
In materials science, quenching is the rapid cooling of a workpiece in water, gas, oil, polymer, air, or other fluids to obtain certain material properties. A type of heat treating , quenching prevents undesired low-temperature processes, such as phase transformations, from occurring.
In chemistry, work-up refers to the series of manipulations required to isolate and purify the product(s) of a chemical reaction. [1] The term is used colloquially to refer to these manipulations, which may include: deactivating any unreacted reagents by quenching a reaction.
In chemistry, a dark quencher (also known as a dark sucker) is a substance that absorbs excitation energy from a fluorophore and dissipates the energy as heat; while a typical (fluorescent) quencher re-emits much of this energy as light. [1] Dark quenchers are used in molecular biology in conjunction with fluorophores.
Instead of a mechanical stopping system, the reaction is halted by quenching, where the products are immediately stopped by freezing, chemical denaturation, or exposure to a denaturing light source. Similar to the continuous-flow method, the time between mixing and quenching can be adjusted by varying the length of the reaction tube.
The reagent removes pairs of H atoms from organic molecules. The stoichiometry of its action is illustrated by the conversion of tetralin to naphthalene: . 2 C 6 Cl 2 (CN) 2 O 2 + C 10 H 12 → 2 C 6 Cl 2 (CN) 2 (OH) 2 + C 10 H 8
During quenching, this allows a slower cooling rate, which allows items with thicker cross-sections to be hardened to greater depths than is possible in plain carbon steel, producing more uniformity in strength. Tempering methods for alloy steels may vary considerably, depending on the type and amount of elements added.
Non-photochemical quenching (NPQ) is a mechanism employed by plants and algae to protect themselves from the adverse effects of high light intensity.It involves the quenching of singlet excited state chlorophylls (Chl) via enhanced internal conversion to the ground state (non-radiative decay), thus harmlessly dissipating excess excitation energy as heat through molecular vibrations.