Talk:Singlet oxygen

message: Comment to Mathchem271828: In the first paragraph, I think it be more appropriate to use S.I. energy units for a energy difference between the two states instead of giving it as a temperature.
* A the moment, it reads "The energy difference...is about 11,400 Kelvins... = 7918.1 cm-1" In dimensional terms, of course, neither K nor cm-1 is an energy. Joules everywhere, please -- no Hartrees, kcal, kcal/mole, kJ/mole, BTU, quads, foot-pounds, etc., etc., unless SI is there first.
:: Wavenumbers is the basic currency that chemists of all types, organic, physical, inorganic.. have an intuitive feel for because we are all familiar with IR spectroscopy.  They are a fully accepted currency of energy as are kelvins for questions of thermodynamics.  SI units are fine for other areas but not for chemistry, in general. Mathchem271828 00:21, 6 February 2007 (UTC)
replies: text: lapo_dk;  I'll just throw this out there that the temperature is good for people to put the data into a thermodynamics perspective.  The temperature might give you an idea of relative populations of the species. Mathchem271828 19:29, 15 December 2006 (UTC)

text: I had that question, too, 4 years later. Given the sorry state of this article, it might be some sort of average! The best I could find on the Web was "lifetime", which is ambiguous. I don't think it can be half-life, because the decay is probably not exponential. Someone who knows should correct this poor information. David Spector (talk) 17:42, 30 December 2011 (UTC)
thread_title:  Comments 

message: The article is self-contradictory: In the introductory paragraph the difference to the ground state is given as 7918.1 cm-1, corresponding to an energy of 94.7 kJ/mol or a wavelength of 1263 nm, while later the energy is given as 94.2 kJ/mol. And what does the "3625 kelvin" in the introductory paragraph refer to? It's not E/kB and not the temperature for maximum radiation in Wien's law, neither in the wavelength nor in the frequency view ... and even if it were, we should use a more common notation here. Icek 12:48, 27 August 2007 (UTC)
replies: text: cf. Talk:Singlet oxygen#Singlet-triplet energy gap. (Sorry for splitting this discussion up...I didn't notice this thread until after I posted.)--GregRM (talk) 03:16, 1 February 2009 (UTC)
thread_title:  Energy difference 

message: Cotton and Wilkinson 6th edition shows 2 singlet states,  the 1Δg where both electrons occupy the same orbital and the 1Σg+ where the electrons are of opposite spin but in different orbitals. The latter is higher energy. Axiosaurus 11:50, 9 November 2007 (UTC)
thread_title: Orbital occupancy of the singlet state

message: Lets hold on to the original image in the lead. The replacement image is in German! so why not have both images V8rik (talk) 21:15, 11 March 2008 (UTC)
thread_title:  what image to use 

message: The text in the diagram currently in the article is not in English. -- Beland (talk) 19:09, 2 June 2008 (UTC)
thread_title:  Image text 

message: I have made the energy gap in the article consistent using the value from the "ChemRev" reference of 7882cm^(-1). The value previously in the article (7918.1 cm^-1) appears in the Webbook link in External links, but Webbook doesn't seem to provide a reference for the singlet state energy. The value from the ChemRev reference appears to agree better with the wavelength used elsewhere in the article of ~1270 nm. (Perhaps the discrepancy between the two references can be explained by the difference between the speed of light in air vs. vacuum?; I have used speed of light in vacuum in my conversions). Thus, I have limited justification for choosing the 7882 value over the 7918.1 value so if someone is familiar with this, feel free to change it to a more accurate value.
Also, I should note that I fixed the temperature. It looks like the correct temperature was originally in the article but was changed to 3625 K(cf. discussion at the top of this page). I believe the correct value is around 11340 K (rather than 3625 K) based on E/k or E/R. (Maybe 3625 K was meant to correspond to something else, like the vibrational temperature?)--GregRM (talk) 03:09, 1 February 2009 (UTC)
replies: text: I have found the reason for the two values of the singlet-triplet energy gap: 7918 and 7882 cm-1. Both values appear in Figure 1 of the Chem. Revs. source article by Schweitzer and Schmidt. 7918 cm-1 is in the column labelled Te, meaning term value for the equilibrium position at the bottom of the potential curve, so that electronic energy is included but not vibrational. 7882 cm-1 is in the column labelled ν00, referring to the difference between v = 0 vibrational levels of the singlet and triplet states. This corresponds to the total singlet-triplet energy difference including vibrational energy, and is therefore the more appropriate value to use, as assumed by GregRM above. 
Similarly for the 1Σ state, the same source gives Te = 13195.2 cm-1 and  ν00 = 13120.9 cm-1, and again we should use the second value. Dirac66 (talk) 19:04, 27 November 2016 (UTC)
thread_title:  Singlet-triplet energy gap 

message: :
I have found the reason for the two values of the singlet-triplet energy gap: 7918 and 7882 cm-1. Both values appear in Figure 1 of the Chem. Revs. source article by Schweitzer and Schmidt. 7918 cm-1 is in the column labelled Te, meaning term value for the equilibrium position at the bottom of the potential curve, so that electronic energy is included but not vibrational. 7882 cm-1 is in the column labelled ν00, referring to the difference between v = 0 vibrational levels of the singlet and triplet states. This corresponds to the total singlet-triplet energy difference including vibrational energy, and is therefore the more appropriate value to use, as assumed by GregRM above. 
Similarly for the 1Σ state, the same source gives Te = 13195.2 cm-1 and  ν00 = 13120.9 cm-1, and again we should use the second value. Dirac66 (talk) 19:04, 27 November 2016 (UTC)
thread_title: Update 2016

message: The below was in the article on Triple Oxygen, shouldn't the same statement be made in this article.
Singlet oxygen, .. is many times more reactive than triplet oxygen,... 
Dave 2346 (talk) 22:10, 19 July 2009 (UTC)
thread_title:  Reactivty 

message: You might want to note that the apparent ene reaction for singlet oxygen is actually only a net ene reaction.  It actually is a non-concerted but non-radical process involving a zwitterionic intermediate.  For more info, or possibly a good sitation for this page see: 
"Mechanism of the ene reaction between singlet oxygen and olefins"
L. M. Stephenson, Mary Jo Grdina, Michael Orfanopoulos
Acc. Chem. Res., 1980, 13 (11), pp 419–425
DOI: 10.1021/ar50155a006
Publication Date: November 1980
Here is the link to the article serving page on the ACS website: http://pubs.acs.org/doi/abs/10.1021/ar50155a006
I only bring this up because I have been seeing a number of young people incorrectly declare this to be a true ene reaction (even in presentations) and many of them seem to be getting their info from here.149.155.3.152 (talk) 18:13, 24 January 2012 (UTC)
replies: text: Yeah, this is a previously known fact, but full treatment of this would require some more work on this, this is why it was weaselled as "ene reaction-like". --vuo (talk) 00:15, 25 January 2012 (UTC)
thread_title:  "Ene" Reaction 

message: The issues I began to address in the first three paragraphs of the lede—which may, in the long run, be shortened, and migrate into the main text—require review by an expert, as does the new combined section on structure and bonding. Need is for a physical or inorganic chemistry professional.
As well, despite relevant, rich secondary and tertiary literature on the subject, the article still fails to present an accessible, self-consistent, readable encyclopedic article (apart from the organic chemistry section stub, and, I hope, the newly revised lede opening.
Note, in today's edit, I found the "blue color" sentence unverifiable (citing an Inorg book with no page nos., and otherwise unsearchable). I corrected that sentence based on an alternative source, not the best, but it was what I could locate. (Because it was badly written — confusing — I was not leaving anything like it in without some source.) 
In addition, I made article opening parallel triplet (3Σg) oxygen article, thereby building on that related article. I then tried to explain, based on sources, the  relationship between triplet oxygen and this article's title "singlet oxygen" concept. including that the 1Δg is but one of the accessible singlet oxygen states.
Have at it, but please do not let it slide back into being unsourced, unscholarly material. Cheers. Le Prof  Leprof 7272 (talk) 03:01, 12 August 2015 (UTC)
thread_title: Call for experts to take this rest of way

message: I am again removing this prose, even though I do not personally disagree with it, because it is a scholarly and professional judgment, and needs to appear with a secondary source.  Or at least in quotes, from the only primary source that appears. Le Prof Leprof 7272 (talk) 16:48, 18 August 2015 (UTC)
thread_title: Making it one of nature's most forbidden transitions

message: The opening paragraph of the lede is indeed much better in its communicating to a general audience than anything that appeared before. There are some things that I think might still need to be done, for the lede of this article to be finished:
* Make clear that the citations provided in the lede actually support the text; for instance, neither the Atkins or Hill citations, as they were originally used, were to explain anything more than oxygen's term symbols, if that, rather they appeared to explain term symbol appearance and interpretation in general. Hence, their relevance to 1O2 needs to be verified (and page numbers provided);
* Check to see, section by section, if the lede captures the most significant content of the sections that appear below; that is, make sure the lede fully reflects the article per WP lede policies and guidelines;
* specifically, make clear that there are more than one singlet oxygens, but it is to one form in particular that the title term routinely refers;
* make clear that the forms interconvert, and, given the long Electronic structure section, here, , consider summarizing how singlet oxygen derives from triplet, ground state oxygen;
* add back some of the key links, such as to the term symbol and other deleted links to basic information (see paragraph deletion, here, , that precipitated this editing flurry), 
* For sake of overall WP encyclopedic content, consider migrating the approach used here, and making comparable changes at the triplet oxygen article, because both interrelate and cross-reference, in their ledes;
* Make sure that the lede content is actually covered by good sources that appear in the main body;
* For comments on other "disappeared" terms appearing in the lede prior to the Leprof edits, see the Talk section immediately above.
* Eventually, choose slightly different language, e.g., than "In terms of," if term symbols is reintroduced to explain the closing term symbol jargon.
That is all I can think of right now. Thanks very much, again, for the clearly helpful lay perspective, and for the IOChem expertise that helped—and in the case of the remaining Electronic structure issues, can only continue helping—make this article accurate, and accessible to a middle range of readers. When I feel welcome again—after the dust settles, and if there is a commitment not to hound—I will return and help out. For now, I will add some lost citations to a Further reading section, and stand by. Cheers. Le Prof.  71.201.62.200 (talk) 06:05, 20 August 2015 (UTC)
thread_title:  Things that might yet be done with the article 

message: The following citations are to books, and currently lack page numbers. Rather than tag them inline, and set off a possible firestorm, I am listing them here, so they receive people's attention:
1. Klán P, Wirz J (2009). Photochemistry of organic compounds: from concepts to practice  [7 occurrences]
2. Atkins P, de Paula J, Friedman R (2009). Quanta, Matter, and Change: A Molecular Approach to Physical Chemistry. [2 occurrences]
15.  Carey FA, Sundberg RJ (1985). Structure and mechanisms (2 ed.)
In addition, the range of this reference is a little wide, per WP standards:
12. Ho RY, Liebman JF, Valentine JS (1995). "Overview of the Energetics and Reactivity of Oxygen"
These are important, esp. the first two, as they appear in the lede, and throughout the text, and in the first case, Klán & Wirz, constitute about 20% of all inline citations.
Will try to help with this later, after things settle down. But in the meantime, wanted everyone to know that ~2 of 4 current citations in the lede can't be traced to material indicated, for lack of page numbers at least (see also first bullet preceding section). Cheers. Le Prof  71.201.62.200 (talk) 06:58, 20 August 2015 (UTC)
thread_title: Current citations to books without page numbers (early article editing legacy)

message: Realizing I knew little about singlet (or triplet) oxygen I went to the term I did recognise -- reactive oxygen species.  There is no reference I could find there to these chemical entities.  Would someone like to review this page too?  Jrfw51 (talk) 15:57, 20 August 2015 (UTC)
replies: text: There is not much chemistry at all in reactive oxygen species.  The article is almost entirely about the importance of ROS to biology and medicine. We should add what they are(including triplet and singlet oxygen) and how they are formed, similar to the type of content contained in reactive nitrogen species. Boghog (talk) 17:10, 20 August 2015 (UTC)

text: Singlet oxygen appears to have a more significant role in photosynthetic plants than in animals. I have added a section on this role to the ROS article. Boghog (talk) 11:15, 22 August 2015 (UTC)
thread_title:  Reactive oxygen species 

message: The article introduces the term dioxidene in the lede, but dioxidene is not defined in the "Oxford Dictionary of Chemistry" (6th ed.) nor does a Google Books search find the term. The term was added in this edit without explanation or citation. --50.53.46.18 (talk) 05:19, 29 September 2015 (UTC)
replies: text: I removed it.  Chemicals have lot of exotic names, some of which are invented by committees with the intention of systematizing our nomenclature. Often these terms are not followed by anyone.  --Smokefoot (talk) 12:40, 29 September 2015 (UTC)
replies: text: Thanks. --50.53.44.211 (talk) 17:32, 29 September 2015 (UTC)
thread_title:  What source defines ''dioxidene''? 

message: The paragraph on singlet-triplet energy difference has a note saying “Original research” for some values, with the following note embedded in the source code (caps not mine):
THE VARYING PRECISIONS OF THESE REPORTED ENERGY EQUIVALENCES MAKES THEM APPEAR TO BE EDITOR CALCULATED, RATHER THAN JOURNAL REPORTED—TO MY EXPERIENCE, A PROFESSIONAL PHYS SCIENTIST WOULD NOT PRESENT 7882 cm-1 = 0.98 eV. AND WHY THE APPROX. FOR THE K VALUE? HENCE THE TAGS. ALTERNATIVELY, THE INDICATED VALUES REFLECT SEPARATE MEASUREMENTS, TO SEPARATE PRECISIONS, AND/OR ARE FROM MORE THAN ONE SOURCE, AND ALL THIS NEEDS TO BE INDICATED IN THE TEXT.
My comments:
1. The sources by Schweitzer and Schmidt and by Atkins and de Paula both state energy differences in cm-1, presumably because they were originally measured by spectroscopy. So I believe each energy value should be given first in cm-1, with the reference given for that value alone.
2. Conversion of units is allowed by Wikipedia policy WP:CALC, which states that Routine calculations do not count as original research, provided there is consensus among editors that the result of the calculation is obvious, correct, and a meaningful reflection of the sources. Basic arithmetic, such as adding numbers, converting units, or calculating a person's age are some examples of routine calculations.
I believe this applies to conversion of cm-1 values to kJ/mol and eV, since the relations between photon wavenumber, molar energy and molecular energy are now considered elementary in chemistry and physics. It should be made clear, however, when the values in kJ/mol and eV are not from the source.
3. The relation of molecular energy to temperature is not a simple unit conversion but is based on the distribution of energy (statistical thermodynamics). This is more complex and could be considered original research, so I will delete the temperature values from the article. Dirac66 (talk) 20:52, 27 November 2016 (UTC)
thread_title:  Conversion of units 

message: "The 1Σ+g state is very short lived and relaxes quickly to the lowest lying 1Δg excited state;[citation needed] it is this lower, O2(1Δg) state that is commonly referred to as singlet oxygen. The energy difference between ground state and singlet oxygen referred to above (e.g., 94.3 kJ/mol) corresponds to a transition in the near-infrared at ~1270 nm.[10] This transition is strictly forbidden by spin, symmetry, and parity selection rules;[[citation needed] hence, direct excitation of ground state oxygen by light to form singlet oxygen is very improbable.[citation needed] As a consequence, singlet oxygen in the gas phase is extremely long lived (72 minutes),[11] although interaction with solvents reduces the lifetime to microseconds or even nanoseconds.[12]"
The first line of this quotation implies that the 1Σ+g to 1Δg is allowed. However, according to the selection rules for electronic transitions in linear molecules it is forbidden as it is not in agreement with the rule  ∆Λ = 0,±1. This is further corroborated by Atkins' Physical Chemistry 7th Edition pg 542 self test 17.1 which lists it as a forbidden transition.
192.76.8.69 (talk) 10:33, 4 February 2018 (UTC)
replies: text: Forbiddeness does not prohibit transitions.  Intersystem crossing often happens rapidly.  But that is as far as I can go.--Smokefoot (talk) 14:53, 4 February 2018 (UTC)
replies: text: Yes, many selection rules are only approximative, and transitions "forbidden" by such rules are often observed with weak intensity. For the specific case of 1Σ+g to 1Δg in dioxygen, see this 1999 review article by Weldon et al., which discusses transitions in both gas phase and solution. See Table 1 on p.372 for the effect of a variety of solvents. Dirac66 (talk) 22:26, 4 February 2018 (UTC)
replies: text: I have now found and added specific lifetime information for both singlet states, in both gas-phase and solution. The upper singlet (1Σ+g) is interesting because it transitions predominantly to the triplet in the gas-phase, but to the lower singlet in solution. Dirac66 (talk) 10:55, 29 March 2018 (UTC)
thread_title:  Basic Error