Quantum yield
McGraw-Hill Science & Technology Dictionary:
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quantum yield
(′kwän·təm ′yēld)
(physical chemistry) For a photochemical reaction, the number of moles of a stated reactant disappearing, or the number of moles of a stated product produced, per einstein of light of the stated wavelength absorbed.
Oxford Dictionary of Biochemistry:
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quantum yield
- abbr.: Q; (in a luminescent system) the probability of luminescence occurring in given conditions, expressed by the ratio of the number of photons, i.e. quanta of light, emitted by the luminescing species to the number absorbed. Compare quantum efficiency. The measurement of Q requires the counting of photons, because
Q = photons emitted/photons absorbed.
It requires highly specialized instrumentation, but a less rigorous method may be employed in which the fluorescence of a fluor is compared with that of a fluor of known Q. Then
Qx = [Ix Qs As]/[Is Ax]
where Qs is the quantum yield of the standard, Is and Ix are the fluorescence intensities of the sample and standard and As and Ax are the percentage of absorption of each solution at the exciting wavelength. - (in photosynthesis) the inverse of quantum requirement; i.e. the fractional number of molecules of carbon dioxide reduced per photon absorbed.
| quantum requirement, quantum number, quantum mechanics | |
| quartz, quasi-species, quaternary |
Wikipedia on Answers.com:
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Quantum yield
The quantum yield (Φ) of a radiation-induced process is the number of times a specific event occurs per photon absorbed by the system. The "event" is typically a kind of chemical reaction.
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Contents
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Applications
The quantum yield for the decomposition of a reactant molecule in a decomposition reaction is defined as:
Quantum yield can also be defined for other events, such as fluorescence:
Here, quantum yield is the emission efficiency of a given fluorophore.
Examples
Quantum yield is used in modeling photosynthesis[1]:
See also
References
- ^ Skillman, J.B. 2008. Quantum yield variation across the three pathways of photosynthesis: not yet out of the dark. Journal of Experimental Botany, 59(7):1647–1661 doi:10.1093/jxb/ern029
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McGraw-Hill Science & Technology Dictionary
McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved.
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Oxford Dictionary of Biochemistry
Oxford University Press. Oxford Dictionary of Biochemistry and Molecular Biology © 1997, 2000, 2006 All rights reserved.
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