Quantum yield

Quantum yield

The quantum yield of a radiation-induced process is the number of times that a defined event occurs per photon absorbed by the system. Thus, the quantum yield is a measure of the efficiency with which absorbed light produces some effect.

For example, in a chemical photodegradation process, when a molecule falls apart after absorbing a light quantum, the quantum yield is the number of destroyed molecules divided by the number of photons absorbed by the system. Since not all photons are absorbed productively, the typical quantum yield will be less than 1.

Quantum yields greater than 1 are possible for photo-induced or radiation-induced chain reactions, in which a single photon may trigger a long chain of transformations. One example is the reaction of hydrogen with chlorine, in which a few hundred molecules of hydrochloric acid are typically formed per quantum of blue light absorbed.

In optical spectroscopy, the quantum yield is the probability that a given quantum state is formed from the system initially prepared in some other quantum state. For example, a singlet to triplet transition quantum yield is the fraction of molecules that, after being photoexcited into a singlet state, cross over to the triplet state. The fluorescence quantum yield is defined as the ratio of the number of photons emitted to the number of photons absorbed.

ee also

Quantum EfficiencyQuantum yield can be defined by the equation:Q= photons emitted/photons absorbed.Quantum yield is essentially the emission efficiency of a given fluorochrome.

External links

* [http://www.jobinyvon.com/Fluorescence/Applications/Quantum-Yield Recording Fluorescence Quantum Yields]


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • quantum yield — noun see quantum efficiency * * * quantum yield see ↑quantum efficiency above. • • • Main Entry: ↑quantum …   Useful english dictionary

  • quantum yield — kvantinis našumas statusas T sritis Standartizacija ir metrologija apibrėžtis Optoelektroninį ar kitokį kvantinį įtaisą apibūdinantis dydis, išreiškiamas jo išėjime pasirodančių ir į jo įėjimą patenkančių elementariųjų dalelių skaičių dalmeniu.… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • quantum yield — kvantinis našumas statusas T sritis fizika atitikmenys: angl. quantum efficiency; quantum yield vok. Quantenausbeute, f rus. квантовый выход, m pranc. rendement quantique, m …   Fizikos terminų žodynas

  • quantum yield — kvantinė išeiga statusas T sritis chemija apibrėžtis Sureagavusių dalelių ir sugertų šviesos kvantų santykis. atitikmenys: angl. quantum yield rus. квантовый выход …   Chemijos terminų aiškinamasis žodynas

  • quantum yield — (= quantum requirement) The number of photons required for the formation of one oxygen molecule in photosynthesis. Varies from 8 14 depending on the system used to measure it …   Dictionary of molecular biology

  • quantum yield — The ratio of the number of photon induced reactions occurring to the total number of incident photons …   Dictionary of automotive terms

  • photochemical quantum yield — fotocheminis kvantinis našumas statusas T sritis fizika atitikmenys: angl. photochemical quantum yield vok. photochemische Quantenausbeute, f rus. фотохимический квантовый выход, m pranc. rendement quantique photochimique, m …   Fizikos terminų žodynas

  • Quantum efficiency — (QE) is a quantity defined for a photosensitive device such as photographic film or a charge coupled device (CCD) as the percentage of photons hitting the photoreactive surface that will produce an electron–hole pair [… …   Wikipedia

  • Quantum dot — Part of a series of articles on Nanomaterials Fullerenes …   Wikipedia

  • quantum efficiency — noun also quantum yield : the ratio of the number of photoelectrons released in a photoelectric process to the number of radiation quanta absorbed * * * quantum efficiency noun In a photocell or in photosynthesis, the number of electrons released …   Useful english dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”