Talk:Nitrogen-vacancy center/GA1

GA Review

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Hi, I'll be reviewing this article. I'll need some time to digest the material, but hope to be done by Friday. Sasata (talk) 16:49, 10 February 2009 (UTC)

Due to the extensive work this article will need to meet GA-standards, I'm failing it for now. However, I hope my relatively detailed laundry list will aid in its improvement. Sasata (talk) 05:18, 14 February 2009 (UTC)

GA review (see here for criteria)

1. It is reasonably well written.

   a (prose): b (MoS):

   I fixed a few obvious errors. The major problem with this article the way it is now, is that only a very small subset of people will be able to really understand it. The text seems to be written with the assumption that readers have background knowledge about the theory of electronic structure and atomic physics. It still has the feel of a graduate-level essay; nothing wrong with adding your old essays to Wikipedia, of course, but it needs to be made more accessible to qualify as GA quality.

2. It is factually accurate and verifiable.

   a (references): b (citations to reliable sources): c(OR):

   A few citations were missing, but the sources used are mostly peer-reviewed journals, with several review articles. Didn't bother to check specific refs this time, based on the other issues.

3. It is broad in its coverage.

   a (major aspects): b (focused):

   The article lacks a better section on the history of the development of the N-V center. Who figured this out? What university? How did theory develop in the years preceding to lead to this person getting the idea to figure this out? This history section would then be placed right after the lead, to help the readers brace themselves for the onslaught of theoretical physics that follows :)

4. It follows the neutral point of view policy.

   Fair representation without bias:

5. It is stable.

   No edit wars etc.:

6. It is illustrated by images, where possible and appropriate.

   a (images are tagged and non-free images have fair use rationales): b (appropriate use with suitable captions):

7. Overall:

   Pass/Fail:

Lead

• "Those remarkable resonances..." peacock word

• "Their complete understanding requires advanced knowledge of quantum optics and is beyond the scope of this paper." "More comprehensible is however..." The article shouldn't be telling the reader how "comprehensible" the material is, I'm sure they'll figure that out themselves.

• "Electron spins at the individual N-V center, localized at atomic scales, can be manipulated at room temperature by applying light, magnetic, electric or microwave fields or their combinations." the second half of this sentence is already stated in the 3rd sentence of the lead.

• The phrase "individual center" is used twice in the latter part of the lead, but sounds awkward. Would not the same idea be equally expressed by leaving out the word "individual"?

• "...and it has potential applications in novel, more efficient fields of electronics and computational science..." please clarify what is meant by a more efficient field of electronic. Does it mean making cheaper/better/technologically advanced electronic components, or something to do with field theory?

Structure

• Clarify what the O is in the picture legend. Also, would "schematic diagram" be better than "primitive picture?"

• wikilink valence electrons, Covalently bond

• "Two of them make a quasi covalent bond and one remains unpaired; the overall symmetry is however axial (trigonal [Molecular symmetry|C3V]) that can be imagined as those three unpaired vacancy electrons continuously exchange their roles." Not sure if there is supposed to be a wikilink in the parentheses somewhere, but if not there should be.

• Might there be a way to show the reader diagrammatically (and simply) the difference in electronic structure between N-V⁰ and N-V^-charge states? A simple picture with some electron spins might help the reader digest some of these concepts. Eg. "In the negative charge state N-V-, the extra electron is located at the vacancy site forming a spin S=1 pair with one of the vacancy electrons." This probably sounds obvious to a physicist, but not, I imagine, to a 1st year university student.

• "This N-V- state is what is commonly, and somewhat incorrectly, called "the nitrogen-vacancy center". The neutral state has not yet been explored for spin manipulations." Is it your opinion that the naming is incorrect? Then its POV or OR; otherwise cit it. Cite the next sentence too.

Production

• clarify what is meant by ..."single substitutional nitrogen centers..."

answer: I don't have time now to check what is already written, so I recap. The diamond is a crystal, and so is formed by evenly spaced (carbon) atoms arranged in a *lattice*. Substitutional defects occur when one of these atom is substituted by another type of atom (nitrogen, in our case). Then, to form an NV, you need that one of the "first neighbour" (one of the four atoms next to the nitrogen in the evenly spaced lattice) is missing, i.e. is a "vacancy". Oakwood (talk) 20:17, 31 July 2010 (UTC)

• I'd like more info on the production of these N-V diamonds. I think its interesting such a wide variety of energy sources can be used: does the irradiation have to be at a specific λ or is it the energy that's more important? Is it simply a matter of sticking your diamond in a high-energy beam and heating it up to make these things? You mentioned ion implantation at the end of the last section, but I'm left wondering if there's some cool application for diamonds that have their N-V centers lined up in a row... etc. Yes, I can probably get more info from the Crystallographic defects in diamond, but a few sentences about the process in this article would be nice.

answer: the NV defects are abundant in natural diamond. Too much abundant, so that it is then difficult to find isolated single one. Is possible to produce synthetic diamond, pure enough to contain no NV centres. Then nitrogen is implanted, and vacancies can be created with radiation (by the way, wavelength IS energy, not to be confused with *intensity*, and yes, it has to be chosen properly). Then heat is used to et the vacancies move into the diamond so to form NVs Oakwood (talk) 20:17, 31 July 2010 (UTC)

• wikilink electrons, protons, neutrons, ions, gamma photons, annealing, micrometre
• "Single substitutional nitrogen produces strain in the diamond lattice; it therefore efficiently captures moving vacancies, producing the N-V centers." The use of the word therefore implies that there is some kind of logical, perhaps obvious connection between lattice strain and electron vacancy capture. Perhaps to a physicist, but you'll have to elaborate a bit more for guys like me.

• "Strain splits and shifts optical transitions from individual centers resulting in broad lines in the ensembles of centers." Again an assumption is made that the reader understands what is meant by "optical transitions", and line broadening, without giving any explanatory lead in. A diagram comparing broad and sharp N-V lines would probably help here. Also, "ensembles of centers" sounds awkward; is this what they're really called in the literature?

Basic optical properties

• "N-V- centers emit bright red light which can be conveniently excited by visible light sources..." It's unclear to me if these diamonds emit light naturally, which can then be excited (this is what the sentence currently implies), or if the bright red light is induced by external excitation (which seems more logical).

answer: though disputable for it's clarity, the sentence doesn't imply that the diamond emits light. It assumes that the reader knows that diamonds don't emit light. Light is emitted if the NV centre is excited. So the sentence mentions details about the wavelengths of exciting and (consequently) emitted light Oakwood (talk) 20:05, 31 July 2010 (UTC)

• I'm not sure what I'm supposed to get out of the absorption/photoluminescence spectrum. Is it significant somehow that the maxima are ~100 nm apart? Are you showing it to illustrate the broadness of the peaks at room T? If so why not also show the narrow peaks at low T for comparison? Please give some context to help me understand it.

• "However, cooling the N-V- centers with liquid nitrogen, or by liquid helium dramatically narrows the lines down to few megahertz width." Reference?

• "An important property of the luminescence from individual N-V- centers is its high temporal stability." Do you mean it's long-lasting? :)

answer: it means that the overall PL process is stable in time, together with its parameters (such as emitted wavelength, intensity etc) Oakwood (talk) 20:20, 31 July 2010 (UTC)

• "Isn't the spin of a photon 1?" —Preceding unsigned comment added by 128.223.198.187 (talk) 01:49, 1 March 2009 (UTC)

Energy level structure and its manipulation by external fields

• This part I found to be very difficult reading, and am of the opinion the whole section needs to be revised with the aim of clarifying terminology and/or reducing the jarring jargon. Some specific examples:

• "Here A means non-degenerate (one state) and E double degeneracy (two states of same energy)." Uh, what exactly is a state? I have to know what that concept is before I can understand the concept of degeneracy, to understand the difference between total spin and antiparallel spin to understand...

• "The number 3=2S+1 in 3A means total spin S=1 and 1 in 1A means S=0 (two antiparallel spins)." Where did this "number" come from? Isn't that an equation? I keep rereading the sentence, but my feeble brain cannot comprehend, sorry. The rest of the section makes my head hurt, too.
• what is this symbol? <-> Is it a double-headed arrow? Surely there must be some ascii character you could use instead?
• "As a final remark, it should be noted..." doesn't sound like an encyclopedia, should be removed.
• "Not this structure alone, but a combination of several favorable factors (previous knowledge, easy production and excitation, etc.) which determined the popularity of the N-V- center." This is not a proper sentence.

• "If a magnetic field is oriented along the defect axis and reaches about 1027 G (or 508 G) then the S=-1 and S=0 states in the ground (or excited) state become equal in energy; they strongly interact resulting in so-called spin polarization". I think that this statement is wrong. The reverse is true - at 1027 G, where there is perfect mixing of states, spin polarization is lost.137.222.189.59 (talk) 12:10, 20 February 2009 (UTC)

the statements are a kind of wrong both: "Whereas ms = −1 (excited state) ↔ ms = 0 (ground state) transition was forbidden in the absence of an external magnetic field, it becomes allowed when a magnetic field mixes the ms = −1 and ms = 0 levels in the ground state." this transition happen each time you turn your laser on NV center on , with or without magnetic field applied, turninig laser on causes spin polarisation, which results in realtime measurable rising fluorescence rate. Spin polarisation has NO problem with Abstinence of external magnetic field. Falling down from excited state -1 into ground state 0 through singulet world is of course forbidden, and that is why, it happens radiationles. 04.11.2014 — Preceding unsigned comment added by 93.215.227.122 (talk) 02:04, 5 November 2014 (UTC)

Historical remarks

• "Priority statements are becoming increasingly popular in the scientific literature, and especially on the Wikipedia pages." The editorial comment certainly doesn't belong.

• "However, a minor error in EPR results (it was assumed that illumination is required to observe N-V- EPR signals) resulted in the incorrect multiplicity assignments in the energy level structure." Reference?

• "The magnetic splitting in the excited state has been measured only recently." Replace with the year or otherwise rephrase.
• "...numerous papers have been published in the major scientific journals and reviewing them is hardly possible on these pages." Sounds like an essay again.

• "Little new science was achieved (except for demonstrating the crucial effect of strain on the large linewidth in the N-V- ensembles). However, this paper has set technical standards for numerous follow-up studies of single N-V- centers." Sounds POV/OR again, needs citation/rewording.