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| | AllRefer.com - maser (Physics) - Encyclopedia (Site not responding. Last check: 2007-11-07) |
 | | The waves produced by the maser are coherent, that is, all of the same frequency, direction, and phase relationship, while the waves produced by most sources of electromagnetic radiation are emitted in all directions over a wide range of frequencies and have all possible phase relationships. |
 | | The principle of the maser was conceived of in the early 1950s, based on the developments of the quantum theory, and the first maser was operated in 1954 by C. Townes, J. Gordon, and H. Zeiger. |
 | | In the maser, electromagnetic radiation is produced by stimulated emission; an atom or molecule in an excited state (i.e., a state of increased energy) emits a photon of a specific frequency when struck by a second photon of the same frequency. |
| reference.allrefer.com /encyclopedia/M/maser.html (560 words) |
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