once-forbidden transitions

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• Forbidden mechanism — A forbidden mechanism or forbidden line is a concept in physics/chemistry. It is a spectral line emitted by atoms undergoing energy transitions not normally allowed by the selection rules of quantum mechanics. In chemistry, forbidden means… …   Wikipedia

• luminescence — luminescent, adj. /looh meuh nes euhns/, n. 1. the emission of light not caused by incandescence and occurring at a temperature below that of incandescent bodies. 2. the light produced by such an emission. [1885 90; < L lumin (see LUMEN) +… …   Universalium

• Magneto-optical trap — experimental setup of the MOT A magneto optical trap (abbreviated MOT) is a device that uses both laser cooling with magneto optical trapping in order to produce samples of cold, trapped, neutral atoms at temperatures as low as several… …   Wikipedia

• nebulium — /neuh byooh lee euhm/, n. Astron. a hypothetical element once thought to be present in emission nebulae because of certain unidentified spectral lines, now known to be forbidden transitions of oxygen and nitrogen ions. [1895 1900; NEBUL(A) + IUM] …   Universalium

• The Wise Men — *Dean Acheson *Charles E. Bohlen *W. Averell Harriman *George F. Kennan *Robert A. Lovett *John J. McCloyThese six friends two lawyers, two bankers, two diplomats came together when Harry Truman became President of the United States in 1945 and… …   Wikipedia

• Tiananmen Square protests of 1989 — Tiananmen Square as seen from the Tiananmen Gate in 2004. The Tiananmen Square protests of 1989, also known as the June Fourth Incident in Chinese[1] (in part to avoid confusion with two prior Tiananmen Square protests), were a series o …   Wikipedia

• china — /chuy neuh/, n. 1. a translucent ceramic material, biscuit fired at a high temperature, its glaze fired at a low temperature. 2. any porcelain ware. 3. plates, cups, saucers, etc., collectively. 4. figurines made of porcelain or ceramic material …   Universalium

• China — /chuy neuh/, n. 1. People s Republic of, a country in E Asia. 1,221,591,778; 3,691,502 sq. mi. (9,560,990 sq. km). Cap.: Beijing. 2. Republic of. Also called Nationalist China. a republic consisting mainly of the island of Taiwan off the SE coast …   Universalium

• performing arts — arts or skills that require public performance, as acting, singing, or dancing. [1945 50] * * * ▪ 2009 Introduction Music Classical.       The last vestiges of the Cold War seemed to thaw for a moment on Feb. 26, 2008, when the unfamiliar strains …   Universalium

• nebula — nebular, adj. /neb yeuh leuh/, n., pl. nebulae / lee , luy /, nebulas. 1. Astron. a. Also called diffuse nebula. a cloud of interstellar gas and dust. Cf. dark nebula, emission nebula, reflection nebula …   Universalium

• radiation — radiational, adj. /ray dee ay sheuhn/, n. 1. Physics. a. the process in which energy is emitted as particles or waves. b. the complete process in which energy is emitted by one body, transmitted through an intervening medium or space, and… …   Universalium