electron paramagnetic resonance
- electron paramagnetic resonance
-
also called electron-spin resonance (ESR)
selective absorption of weak radio-frequency electromagnetic radiation (in the microwave region) by unpaired electrons in the atomic structure of certain materials that simultaneously are subjected to a constant, strong magnetic field. The unpaired electrons, because of their spin, behave like tiny magnets. When materials containing such electrons are subjected to a strong stationary magnetic field, the magnetic axes of the unpaired electrons, or elementary magnets, partially align themselves with the strong external field, and they precess in the field much as the axes of spinning tops often trace cone-shaped surfaces as they precess in the gravitational field of the Earth.
resonance is the absorption of energy from the weak alternating magnetic field of the microwave when its frequency corresponds to the natural frequency of
precession of the elementary magnets. When either the microwave frequency or the stationary field strength is varied and the other is kept fixed, the measurement of radiation absorbed as a function of the changing variable gives an electron paramagnetic resonance spectrum. Such a spectrum, typically a graph of microwave energy absorption versus applied stationary magnetic field, is used to identify paramagnetic substances and to investigate the nature of chemical bonds within molecules by identifying unpaired electrons and their interaction with the immediate surroundings.
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Universalium.
2010.
Look at other dictionaries:
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electron paramagnetic resonance — paramagnetinis elektronų rezonansas statusas T sritis fizika atitikmenys: angl. electron paramagnetic resonance vok. elektronenparamagnetische Resonanz, f rus. электронный парамагнитный резонанс, m pranc. résonance paramagnétique électronique, f … Fizikos terminų žodynas
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electron paramagnetic resonance method — paramagnetinio elektronų rezonanso metodas statusas T sritis fizika atitikmenys: angl. electron paramagnetic resonance method; EPR method vok. paramagnetische Elektronenresonanzmethode, f rus. метод электронного парамагнитного резонанса, m; ЭПР… … Fizikos terminų žodynas
electron paramagnetic resonance spectroscopy — paramagnetinio elektronų rezonanso spektroskopija statusas T sritis fizika atitikmenys: angl. electron paramagnetic resonance spectroscopy vok. paramagnetische Resonanzspektroskopie, f rus. спектроскопия электронного парамагнитного резонанса, f… … Fizikos terminų žodynas
electron paramagnetic resonance — noun Physics a phenomenon exhibited by paramagnetic substances in which the spin of an unpaired electron aligns itself with a magnetic field. Used in molecular structure analysis. Abbrev.: EPR Also, electron spin resonance …
electron paramagnetic resonance — noun microwave spectroscopy in which there is resonant absorption of radiation by a paramagnet • Syn: ↑electron spin resonance, ↑ESR • Hypernyms: ↑microwave spectroscopy * * * noun : electron spin resonance he … Useful english dictionary
