Talk:Förster resonance energy transfer

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NO PHOTONS involved
In the introduction "virtual photons" are mentioned. This is not true, because if there were virtual photons the distance dependency would be 1/r² and not 1/r^6...Essentially there are no photons involved, also no virtual ones! —Preceding unsigned comment added by 141.84.253.121 (talk) 16:29, 7 March 2009 (UTC)


 * Agreed, the mechanism of interaction is via a dipole-induced-dipole interaction. Corrected accordingly. --Trevva (talk) 09:09, 4 May 2009 (UTC)


 * The term ‘virtual photon’ in the introduction is correct (see G. D. Scholes, Annu. Rev. Phys. Chem. 54 (2003) 57–87; A. Salam, J. Chem. Phys. 122 (2005) 044112; G. J. Daniels, R. D. Jenkins, D. S. Bradshaw and D. L. Andrews, J. Chem. Phys. 119 (2003) 2264-2274; P. Andrew and W. L. Barnes, Science 290 (2000) 785-788; C. E. Finlayson, D. S. Ginger and N. C. Greenham, Chem. Phys. Lett. 338 (2001) 83-87; D. P. Craig and T. Thirunamachandran, ‘Molecular Quantum Electrodynamics’, Dover Publications, 1998, p. 142). The 1/r² distance dependence corresponds to radiative transfer, which is mediated by a real photon.  In contrast, non-radiative (Forster) transfer involves a virtual photon in the language of quantum electrodynamics.  The latter theory, unsurpassed in the description of light-matter interactions, is unequalled in accuracy in comparison to experiment.  It is correct to say that a real photon process does not correspond to 1/r6, but it is a virtual photon that couples the transition dipole moments in FRET. C230057 (talk) 11:20, 2 June 2009 (UTC)

The introduction mentions that the existence of an actual intermediary photon would violate conservation of energy and momentum, but no explanation is given. Does anyone know why this is (and want to add it to the article)? I tried to look online but found no simple answer. 68.51.77.115 (talk) 03:20, 14 October 2009 (UTC)


 * The rules of conservation of energy and momentum can temporarily be suspended due to the Heisenberg uncertainty principle. This allows for the creation and annihilation of a virtual photon over a minuscule intermediary time-period.  Following the annihilation of the virtual photon, energy and momentum are conserved.  —Preceding unsigned comment added by C230057 (talk • contribs) 09:38, 16 October 2009 (UTC)


 * All electro-magnetic forces are intermediated by virtual photons.

--134.2.187.63 (talk) 16:57, 17 January 2011 (UTC)

"Fluorescense" ten times more common than "Förster"
Why is this article named "Förster Resonance Energy Transfer" instead of "Förster Resonance Energy Transfer" when the latter one is occuring something like ten times more often on Google than the first one? (Try searching for both with exact phrase matching). --SHL-at-Sv (talk) 18:28, 26 May 2008 (UTC)


 * Because Fluorescence Resonance Energy Transfer is more of a colloquial name. It's convenient because the technique exploits the physical phenomenon of fluorescence for the detection. The proper name is Förster, which is the scientist responsible for theorizing the technique.  Wisdom89  ( T |undefined /  C ) 18:46, 26 May 2008 (UTC)


 * Ok, thanks. --SHL-at-Sv (talk) 08:25, 27 May 2008 (UTC)

I disagree with wisdom89. Foerster showed how to extend the theory of atomic dipole-dipole energy transfer to molecular fluorescence. Therefore his name should be associated with the theory that predicts a R^6 dependence on distance to the rate of energy transfer. The phenomenon itself was not first characterized by Foerster. I know it's a subtle point, but I think it's important. The scientifically proper name for the process would be something like molecular dipole resonant energy transfer or resonant electronic energy transfer. Many people simply use Resonant Energy Transfer. Since we're mostly stuck with "FRET", Foerster's name is probably a better choice than fluorescence for the "F" since "FRET" can occur (and the theory is the same) even if there is no fluorescence to be observed. On the other hand, using "F" as fluorescence to refer to the technique used to measure it is perfectly acceptable and is not a "colloquial" use. Some discussion of this point in the article would be useful.

On another note, I'd like to see both citation 1 and citation 5 be deleted from the reference list since there is nothing special about either article. A better choice would be some review articles. Perhaps the Stryer article that popularized FRET as a "molecular ruler". An imaging review would be nice. Something about the application of FRET to look at molecular motions would be appropriate. Perhaps we could add a link to one of the many articles reviewing kappa-squared effects, etc.

There are many statements that clearly reflect a point-of-view that is quite narrow. "The most popular" for example. —Preceding unsigned comment added by 128.6.78.31 (talk) 23:04, 8 August 2008 (UTC)

Absolutely no one in the field calls FRET - Förster Resonance Energy Transfer. Did Förster himself create this page? His involvement in the development of the technique is also disputed. What a crock! 152.3.248.112 (talk) —Preceding undated comment was added at 05:22, 24 September 2008 (UTC).


 * Although it is correct that Förster did not actually discover the phenomenon of "fluorescence resonance energy transfer," he was the first to accurately quantify the phenomenon in 1948. He basically bridged the gap between experiment and theory.  Seems pretty important to me!  For more info, read the preface to the 2005 book edited by A. Periasamy and R.N. Day entitled "Molecular Imaging: FRET Microscopy and Spectroscopy." (ISBN 019-517720-7) Yiddy55 (talk) 15:13, 17 November 2008 (UTC)
 * Fluorescence RET is also a misleading term, use of Förster avoids implying the involvement of any fluorescence. :Just look at the Frenkel-exciton transfer in organic solar cells or in photosynthesis.
 * --134.2.187.63 (talk) 17:05, 17 January 2011 (UTC)

Never heard of Foerster. —Preceding unsigned comment added by 128.104.193.228 (talk) 13:09, 15 December 2008 (UTC)


 * just because most people get it wrong does not make it right! take italian food: only Italians known how to pronounce the stuff properly, while we Anglophones make up the spelling: just because there are more than 10 times more of us than then does not make it right! Another example is vagina, which most people thing is the vulva, whereas it is part of it. The examples go on and on! Squidonius (talk)


 * Squidonius = Awesomeness.'' Kmarinas86 (6sin8karma) 00:52, 14 June 2010 (UTC)

I have quickly checked all the science textbooks I own, plus the references cited. Practically no one calls it Förster Resonance Energy Transfer, including the bibles of the field, such as Lakowicz. This has nothing to do with what people get wrong or right; this technique has an established name. It is --in academia, textbooks, scientific literature and even google-- as Fluorescence Resonance Energy Transfer. I would like to see numerous examples of mainstream literature referring to Forster Resonance Energy Transfer: If not, I will ask for the article to be moved to Fluorescence Resonance Energy Transfer. This appears to me as POV.

For those who like fancy prizes, I just checked Roger Tsien's recent Nobel lecture (Nobel Prize in Chemistry), and Tsien does refer to it as Fluorescence Resonance Energy Transfer. See http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2008/tsien_lecture.pdf Enozkan (talk) 19:20, 21 March 2013 (UTC)


 * I have now looked at some more of the references mentioned, and can see some (and mostly recent) mentions of Förster Resonance Energy Transfer. However, scientists still use Fluorescence Resonance Energy Transfer, as the more common name for it, it is accurate and is not colloquial. Enozkan (talk) 19:45, 21 March 2013 (UTC)


 * My final note on this subject - Despite the common usage among a majority of scientists, IUPAC does consider Förster Resonance Energy Transfer as the full name for FRET. This is due to their strict reading of the name "Fluorescence Resonance Energy Transfer", despite historical usage by those who do FRET. So, this acronym may be slowly re-purposed. Enozkan (talk) 03:34, 25 March 2013 (UTC)

People in the field definitely predominantly call it Fluorescence RET but Förster RET is not completely absent, however being that Förster was literally a member of the Nazi party I (a biochemist, aka someone in the field) prefer Fluorescence RET because not only is it more common but it avoids commemorating Nazis - who killed my family — Preceding unsigned comment added by 141.89.201.219 (talk) 12:11, 14 October 2019 (UTC)

Fluorescence in the life sciences
Fluorescence in the life sciences has now its own article as Fluorescence was the general page. I do not want edit wars so could someone link it in here, plz? Plus there is a nicer picture there of FRET. Squidonius (talk) Post edited on --Squidonius (talk) 14:04, 7 August 2009 (UTC)

I don't see why this would cause any sort of edit war; we should be bold - so I changed it. If someone disagrees, we can then discuss it here. Cheers,  Chzz  ►  08:29, 11 October 2009 (UTC)

Förster distance
I took a closer look to the formulas for the distance in the literature. Although all formulas show proportionality between R06 and Q0, &kappa;2, n-4 and J, you can see major differences in the constant part (c0 in the IUPAC Goldbook). The formula presented in the en:wikipedia is identical with those in Jares-Erijman & Jovin, 2004. But what about the Transfert d'énergie entre molécules fluorescentes, IUPAC-Golgbook, Demchenko's "Introduction to Fluorescence Sensing". What is (are) the right one? --Sven Jähnichen (talk) 10:28, 5 February 2010 (UTC)

Förster distance ambiguity I
The Förster distance equation is listed in, equation 13.4 page 445.
 * (1) $$ {R_0}^6 = \frac{9000 \,(\ln 10) \, \kappa^2 \,Q_D}{128 \, \pi^5 \, N_A \,n^4} J(\lambda) = \frac{9000 \,(\ln 10) \, \kappa^2 \,Q_D}{128 \, \pi^5 \, N_A \,n^4} \frac{\int F_{\rm D}(\lambda) \, \epsilon_{\rm A}(\lambda) \, \lambda^4 \, d\lambda}{\int F_{\rm D}(\lambda) \, d\lambda} $$

Where the spectral overlap is normalized to unity by dividing by its area.

Equation 13.6 page 446 list the following. If the wavelength is expressed in nm, $$ \epsilon_{\rm A}(\lambda) $$ is in units of $$ M^{-1} cm^{-1}$$ then the integral is in units of $$ M^{-1} cm^{-1} (nm)^4 $$ where the Förster distance in Ångstrom is given by:
 * (2) $$ {R_0}^6 = 8.79*10^{-5}\frac{\kappa^2 \, Q_D}{n^4} J(\lambda) \, ({\rm in} \, A^{6})$$

Equation (2) gives a true result when working out problem P13.5 page 474, answer page 908. Personal data also reveal equation (2) to be the right. Equations (1) and (2) are not equal. There is a factor 1000 in difference. I believe that the difference stems from a wrong unit conversion in early papers. But it is not clear where this occurs. I am currently looking through older litterature of Förster. The suggested corrected equation is:
 * (3) $$ {R_0}^6 = \frac{9 \,(\ln 10) \, \kappa^2 \,Q_D}{128 \, \pi^5 \, N_A \,n^4} J(\lambda) = \frac{9 \,(\ln 10) \, \kappa^2 \,Q_D}{128 \, \pi^5 \, N_A \,n^4} \frac{\int F_{\rm D}(\lambda) \, \epsilon_{\rm A}(\lambda) \, \lambda^4 \, d\lambda}{\int F_{\rm D}(\lambda) \, d\lambda} $$

From equation (3), unit calculations follows as:

If the wavelength is expressed in nm, $$ \epsilon_{\rm A}(\lambda) $$ is in units of $$ M^{-1} cm^{-1}$$ then the integral is in units of $$ M^{-1} cm^{-1} (nm)^4 $$ where the Förster distance in Ångstrom is given by:
 * (4) $$ {R_0}^6 = \frac{9 \,(\ln 10)}{128 \, \pi^5 \, N_A} \, \frac{\kappa^2 \,Q_D}{n^4} {\int F_{\rm D}(\lambda) \, \epsilon_{\rm A}(\lambda) \, \lambda^4 \, d\lambda}$$ $$ = 8.79\cdot{}10^{-28} {\rm mol} \, \frac{\kappa^2 \,Q_D}{n^4} \, J(x) \, {\rm cm}^{-1} \, {\rm nm}^{4} \, \frac$$$$ = 8.79\cdot{}10^{-28}{\rm mol}\cdot{}(100{\rm m}^{-1} \cdot{} (10^{-9})^{4}{\rm m}^4)\cdot{}10^{-3}{\rm m}^{3} {\rm mol}^{-1} \cdot{}  \frac{\kappa^2 \,Q_D}{n^4} \cdot{} J(x)$$$$ = 8.79\cdot{}10^{-65}{\rm m}^{6} \cdot{}  \frac{\kappa^2 \,Q_D}{n^4} \cdot{} J(x)$$$$ =  8.79\cdot{}10^{-5}{\rm Ang}^{6} \cdot{}  \frac{\kappa^2 \,Q_D}{n^4} \cdot{} J(x) $$

which shows equation (2) and (3) are equal, and hence the corrected form should be correct. Values of J(x) should be in the area $$10^{13}-10^{15}$$.

If the wavelength is expressed in cm and $$ \epsilon_{\rm A}(\lambda) $$ is in units of $$ M^{-1} cm^{-1}$$ then the integral is in units of $$ M^{-1} cm^{3} $$ where the Förster distance in Ångstrom is given by:
 * (5) $$ {R_0}^6 = \frac{9 \,(\ln 10)}{128 \, \pi^5 \, N_A} \, \frac{\kappa^2 \,Q_D}{n^4} {\int F_{\rm D}(\lambda) \, \epsilon_{\rm A}(\lambda) \, \lambda^4 \, d\lambda}$$ $$ = 8.79\cdot{}10^{-28} {\rm mol} \, \frac{\kappa^2 \,Q_D}{n^4} \, J(x) \, {\rm cm}^{3} \, \frac$$$$ = 8.79\cdot{}10^{-28}{\rm mol}\cdot{}((10^{-2})^{3}{\rm m}^3)\cdot{}10^{-3}{\rm m}^{3} {\rm mol}^{-1} \cdot{} \frac{\kappa^2 \,Q_D}{n^4} \cdot{} J(x)$$$$ = 8.79\cdot{}10^{-37}{\rm m}^{6} \cdot{} \frac{\kappa^2 \,Q_D}{n^4} \cdot{} J(x)$$$$ = 8.79\cdot{}10^{-25}{\rm cm}^{6} \cdot{}  \frac{\kappa^2 \,Q_D}{n^4} \cdot{} J(x) $$$$ =  8.79\cdot{}10^{23}{\rm Ang}^{6} \cdot{}  \frac{\kappa^2 \,Q_D}{n^4} \cdot{} J(x)$$

Förster distance ambiguity II
I removed the following paragraph from the article page:

″It appears that the referred equation for Förster distance is not consistent in the book (Joseph R. Lakowicz, Principles of Fluorescence Spectroscopy) (page 445,446). A factor 1000 is wrong. A calculation of units, shows that the equation should instead read:
 * $$ {R_0}^6 = \frac{9 \,(\ln 10) \, \kappa^2 \,Q_D}{128 \, \pi^5 \, N_A \,n^4} J(\lambda) = \frac{9 \,(\ln 10) \, \kappa^2 \,Q_D}{128 \, \pi^5 \, N_A \,n^4} \frac{\int F_{\rm D}(\lambda) \, \epsilon_{\rm A}(\lambda) \, \lambda^4 \, d\lambda}{\int F_{\rm D}(\lambda) \, d\lambda} $$

This conclusion needs reference to original scientific papers. See discussion tab: Förster distance ambiguity″

If the equation in the article is wrong, and you have a source, then just change the equation. The above is discussion. 128.200.11.106 (talk) 18:49, 25 May 2011 (UTC)

Förster distance ambiguity III
I think the problem lies in the conversion of the original J coefficient in the Förster equation (which uses the cross-sectional absorptivity coefficient, σ) into the extinction coefficient, ε. See Molar_attenuation_coefficient.

This is the derivative from the original rate of energy transfer equation with σ:


 * (6) $$ {R_0}^6 = \frac{9}{128 \, \pi^5} \, \frac{\kappa^2 \,Q_D}{n^4} {\int F_{\rm D}(\lambda) \, \sigma_{\rm A}(\lambda) \, \lambda^4 \, d\lambda}$$

See http://spie.org/samples/PM194.pdf

The equation should read when using ε:


 * (7) $$ {R_0}^6 = \frac{2.07}{128 \, \pi^5 \, N_A} \, \frac{\kappa^2 \,Q_D}{n^4} {\int F_{\rm D}(\lambda) \, \epsilon_{\rm A}(\lambda) \, \lambda^4 \, d\lambda} $$

2.07 is a result of 9*Ln(10)/10. As σ = Ln(10)/ 10 $$ {N_a} $$ ε (in m^2). — Preceding unsigned comment added by 176.61.9.30 (talk) 00:25, 20 November 2015 (UTC)

Competition for Förster
I found this article and think it is relevant to this page. However, it seems premature to alter an encyclopedic entry based on one study. Never the less, documenting it on the talk page seemed appropriate. In short, the study shows that energy transfer can occur at near 100% efficiency between dipoles even if they are orthogonal to each other. According to the authors, this refutes Förster's theory since parallel orientations are required for his dipole resonant mechanism to function. The authors suggest a "low-frequency mode of coupling via intramolecular vibrations." But it seems that this suggestion requires more corroboration. Cheers, Wolfworks (talk) 17:34, 7 December 2010 (UTC)

Demonstration Video
I added a demonstration video of FRET happening to the 'see also' section, but the video may be a better example if it is embedded at the top of the article. The video is seen here:

Additional citations for verification?
I'd like to remove the refimprove template. I think the article has sufficient references now. I will continue to work on replacing primary sources and formatting references. Thoughts? Mllyjn (talk) 02:13, 8 October 2012 (UTC)

I'm going to go ahead and take it down. Mllyjn (talk) 02:37, 15 October 2012 (UTC)

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Jablonski diagram
The Jablonski diagram might be misleading as the energy levels of donor and acceptor don't have to be equal, only the energy difference has to match. — Preceding unsigned comment added by 132.230.171.51 (talk) 17:52, 8 September 2017 (UTC)

Spelling error in diagram
Any chance of getting the correct spelling of Fluorophore onto the second image? Plant surfer 10:55, 1 March 2016 (UTC)

A reference to the photosynthesis antenna complex?
After all the high tech talk upwards, a duller coment.

At least for me this page is a big deal because of that, so maybe some reference to it somewhere. Besides, it's the way photons are included into organic matter... this is the page I'm referring: https://en.wikipedia.org/wiki/Light-harvesting_complex

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"Resonance"
What does the word "resonance" signify in the term "FRET"? The article contains it only in the combination "resonance energy transfer", but also uses just "energy transfer" many times and does not explain what this "resonance" is supposed to mean here. — Mikhail Ryazanov (talk) 21:35, 26 July 2019 (UTC)

^^The transfer of energy in FRET is due to the oscillations of electrons between different energy levels which fluctuate in a resonant fashion i.e. together and influenced by each other. This happens in a distant dependent manner, sort of like how if one tuning fork when striken can cause another to begin vibrating when put in close proximity.142.103.118.1 (talk) 18:27, 19 November 2019 (UTC)

Applications
I rearranged the information already present in the applications section to fall into more clear-cut categories than "biology" or "chemistry." I also added details as well as other potential applications of FRET. Snowwhite5567 (talk) 06:43, 17 November 2020 (UTC)