once-forbidden transitions
1Forbidden 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… …
2luminescence — 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) +… …
3Magneto-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… …
4nebulium — /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] …
5The 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… …
6Tiananmen 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 …
7china — /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 …
8China — /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 …
9performing 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 …
10nebula — 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 …
