 |
|
| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z |
|
|
maser
A source of very intense, narrow-band, coherent microwave radiation. "Maser" stands for "microwave amplification by stimulated emission of radiation." Masers (and their optical counterpart, lasers) involve the interaction between an electromagnetic wave of a certain wavelength and an atom or a molecule in a suitable (excited) energetic state. The passage of the wave triggers the atom/molecule to give up energy in the form of more radiation of exactly the same wavelength. This reinforces the passing wave, which can then interact with more excited atoms to build up a well-directed, intense pulse of monochromatic (single-wavelength) radiation.
The principle of the maser was discovered by Charles Townes of Columbia University, for which he shared the 1964 Nobel Prize in Physics with Nikolai Basov and Alexander Prokhorov, who also worked in this field. The first maser used electrostatic (charged) plates to separate high-energy ammonia molecules from low-energy ones. Radiation of a certain frequency stimulated the high energy ammonia molecules to emit similar radiation and strengthen the signal. The very narrow frequency emitted made the ammonia maser one of the most accurate atomic clocks known.
Several types of interstellar maser have been identified but, as yet, no optical or infrared astrophysical lasers.
Related category
• INSTRUMENTATION
Also on this site:
Encyclopedia of Alternative Energy & Sustainable Living
Encyclopedia of History
Transport Concepts & Designs (partner site)