Talk:Ultraviolet/Archive 2

copied from Talk:Ultraviolet/Comments

I was looking for frequency ranges for the three UV bands. The article mentions the band, but does not authoritatively link the band names to the wavelengths. —66.83.109.202 18:32, 27 February 2007‎

The article now includes details of UVA, UVB, UVC. Future comments will be seen more quickly if posted directly to Talk:Ultraviolet. —Patrug (talk) 08:58, 13 July 2014 (UTC)

edit

I added an example and citation of an animal, Colias eurytheme, that uses UV absorption for sexual selection under the “Blockers and Absorbers” header Kzyoung (talk) 18:58, 14 November 2013 (UTC)

"UV Degradation of Solar Cells"?

There's a subheading called UV Solar Cells and UV degradation of solar cells. It does discuss UV cells and applications to window glass. However, nowhere within does it cover the degradation of solar cells. Is this content missing? Was it removed at some point in the past? Or should we simply delete the "degradation" part of the heading? http://en.wikipedia.org/wiki/Ultraviolet#UV_solar_cells_and_UV_degration_of_solar_cells --JB Gnome (talk) 06:13, 24 May 2009 (UTC)

Removed. Most solar cell degradation is from dirt & heat, not UV. —Patrug (talk) 15:22, 11 July 2014 (UTC)

Move?

Shouldn't the page be called "ultraviolet light"? WLU (t) (c) Wikipedia's rules:^simple/_complex 15:41, 24 April 2009 (UTC)

No. A definitive authority on "light" is the International Commission on Illumination (CIE). Together with the International Electrotechnical Commission (IEC), they define "light" in terms of its ability to "stimulate the organ of vision." Violet and UV are distinct because the former produces a visual stimulus in most humans while the latter does not. Accordingly, a name change would be inappropriate. Note that both "UV" and "UV light" redirect to this article. This seems sensible to me. Lovibond (talk) 16:58, 28 April 2009 (UTC)

Good point. Still, ultraviolet seems like an adjective rather than a noun. Ultraviolet radiation? Are there any possible synonyms that would make sense? WLU (t) (c) Wikipedia's rules:^simple/_complex 00:13, 6 May 2009 (UTC)

It seems as much a noun as red, or blue, or orange....I can't think of any other context that uses "ultraviolet," so it doesn't seem to me that adding "radiation" or "electromagnetic radiation" would pass Occam's razor.Lovibond (talk) 18:36, 6 May 2009 (UTC)

It looks like it's my lack of familiarity - dictionary.com uses it as a noun as well as an adjective. Fair 'nuff. WLU (t) (c) Wikipedia's rules:^simple/_complex 18:45, 6 May 2009 (UTC)

probable mistake

The article states that "The sun emits ultraviolet radiation in the UVA, UVB, and UVC bands. The Earth's ozone layer blocks 98.7% of this UV radiation from penetrating through the atmosphere. 98.7% of the ultraviolet radiation that reaches the Earth's surface is UVA." This seems unlikely to be correct. First, it seems extremely unlikely that both figures would just happen to be 98.7%. Also, whoever wrote this seems to be suffering from the fallacy of false precision. Ozone levels vary considerably, so I doubt that the absorption factor can be given to 3 significant figures. For example, this NASA web page http://www.nas.nasa.gov/About/Education/Ozone/ozonelayer.html gives the figure as 97-99%.--75.83.69.196 (talk) 02:12, 25 December 2009 (UTC)

Also: Later on the same paragraph: "(Some of the UVB and UVC radiation is responsible for the generation of the ozone layer.)" Half-right; UVC photolyses oxygen (O2) to form 2 reactive O atoms, each of which then react with another O2 to form 2 O3's. UVB photolyses O3 to O2 and O. 94.192.85.14 (talk) 06:37, 10 January 2010 (UTC)

These mistakes no longer appear in the article. —Patrug (talk) 15:22, 11 July 2014 (UTC)

Edit for clarity?

Under the Subtypes section, where it says "See 1 E-7 m for a list of objects of comparable sizes", the sentence was unclear to me until I clicked on the link. Would it be possible to change it to say something like "objects of sizes comparable to ultraviolet wavelengths"? I wanted to change it myself but don't have access rights to do that.

98.172.69.7 (talk) 17:30, 21 January 2010 (UTC)

This no longer appears in the article. —Patrug (talk) 15:22, 11 July 2014 (UTC)

Is UV fungicidal?

Anyone have any such info? —Preceding unsigned comment added by Aadieu (talk • contribs) 19:33, 9 February 2010 (UTC)

Yes. The Phototherapy section now includes UV treatment for toenail fungus. —Patrug (talk) 15:22, 11 July 2014 (UTC)

XUV

Can someone please confirm whether "XUV" is another abbreviation for extreme ultraviolet, and if so, add it to the Subtypes section? (And perhaps also to the extreme ultraviolet article?) --Kyuzo2000 (talk) 16:35, 25 March 2010 (UTC)

I had a look at Web of Science: there are 2113 hits when searching for Topic=XUV and 8483 hits for EUV. In all articles I looked at these abbrevations referred to extreme ultraviolet. There seems to be some tendency towards using XUV in atomic and laser physics, and for EUV in astronomy and lithography, but overall I think we can conclude that both EUV and XUV are used and should be mentioned. — HHHIPPO 19:32, 23 July 2012 (UTC)

Update, after some more research: XUV can also be used as abbrevation for "X-ray Ultraviolet", that is, soft X-rays. Both for EUV and for the two meanings of XUV there are many definitions regarding the wavelength range they refer to, see e.g.

• http://www.laserfocusworld.com/blogs/photonics_buildingblocks/2012/05/euv-xuv-acronym.html
• http://alexandria.tue.nl/extra2/200213294.pdf
• http://www.ann-geophys.net/26/269/2008/angeo-26-269-2008.pdf

The most 'official' definition is given by the already cited ISO standard 21348 (describing XUV as "Soft X-rays" with wavelengths of 0.1-10 nm). I suggest we mention this both here and in the extreme ultraviolet article, and check the various occurences of both abbrevations for consistency.

I'll start this soon, maybe also polishing some other edges on the way. Feel free to revert if anything is not agreeable. — HHHIPPO 19:02, 24 July 2012 (UTC)

Medical Uses

The section on medical uses talks about gamma rays coming from UV sources. I am not an expert, but from what I understand, gamma rays are a shorter wavelength than the peak emission of mercury vapor, and no phosphor can reemit light with a shorter wavelength than the light that stimulated it. That would make it impossible for a fluorescent mercury vapor lamp to produce gamma rays.

It also suggests that snoring might be cured. This is all highly dubious in my opinion. --Avidiax (talk) 18:08, 27 March 2010 (UTC)

I have just removed it all - any sentence that starts off with "it has been scientifically proven" and then doesn't provide a peer-reviewed source is just asking for trouble. The para had the feel of something that was added by someone trying to sell some "treatments" and backs up its sales pitch with a wikipedia link. On your shorter wavelength query, you are right to be sceptical of the claim, because in this case it is rubbish - but in general, excitation at lower energy than emission is certainly possible (Two-photon absorption) - but it is a low probability event - and very difficult with a lamp (high intensities are needed, more suitable from a laser than a lamp), and in this case total junk as going from UV to gamma ray via multi-photon absorption is basically impossible. SFC9394 (talk) 19:26, 27 March 2010 (UTC)

Ionizing radiation?

UV is called ionizing. AFAIK it can break chemical bonds but it does not have enough energy to ionizing.--128.214.182.110 (talk) 11:27, 7 April 2010 (UTC)

Electrons in different 'shells' of atoms of different elements have different ionization energies/thresholds - the amount of energy needed to remove those electrons. Some electrons (e.g. in the inner shells of large atoms) have very high ionization thresholds and could not be ejected by ultraviolet radiation. But UV does have enough energy to remove some electrons from atoms of many elements. --213.104.249.48 (talk) 11:41, 30 October 2010 (UTC)

This is an old remark, but instead of letting it sit here, I will remind all that it's not true. Most of the UV band doesn't have enough energy to remove any electron from any atom. The "ionizing radiation" like action is due to UV's power to excite chemical bonds and cause free radicals, or damage similar to ionization damage, without actual ionization. Free radicals can be produced without ionization-- it happens all the time. SBHarris 23:41, 24 July 2012 (UTC)

Reference PDF at NIST hangs Firefox

It's ref#9 in the section "Detecting and measuring UV radiation" at:

http://ts.nist.gov/MeasurementServices/Calibrations/upload/JES-80.PDF

I went there and began viewing the PDF; scrolled down and the second page of the PDF wouldn't load. Firefox became unresponsive. --Mvsmith (talk) 17:11, 5 May 2010 (UTC)

Works fine for me on Opera, but I'm using an external PDF viewer. Probably a browser or plugin bug (I suspect it's a plugin bug).—Tetracube (talk) 17:57, 5 May 2010 (UTC)

Rest rooms

Currently we have sourced information that UV lighting is installed in public rest rooms to deter intravenous drug-taking (albeit the news report cited seems more interested in its supposed effect in encouraging sexual encounters). A quick google suggests that this news story has got it wrong: most accounts suggest that it's just ordinary blue light, which gives the whole surface a of the skin a blue tinge and thus makes the veins harder to spot. I propose to delete this, subject to other editors' views. --Old Moonraker (talk) 07:11, 14 July 2010 (UTC)

No defenders: done. --Old Moonraker (talk) 12:09, 29 December 2010 (UTC)

Supraviolet

It should obviously be termed "supraviolet" in conformity with the logic of the term "infrared." —Preceding unsigned comment added by 129.98.192.55 (talk) 01:03, 22 August 2010 (UTC)

Perhaps--but you would need to take that up in the halls of science first, not at Wikipedia. Darkest tree (talk) 00:25, 5 April 2011 (UTC)

Proposed page move

The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the proposal was not moved per unanimous consensus.--Fuhghettaboutit (talk) 09:52, 5 January 2011 (UTC)

---

Ultraviolet → Ultraviolet (light) — Banaticus (talk) 10:42, 29 December 2010 (UTC)

The page is entitled "Ultraviolet" but is this ultraviolet (the specific frequency) or ultraviolet (the color)? It's apparently necessary to specify -- the current lead section of the page even starts, "ultraviolet light". So, why make the page title ambiguous? The specific word "ultraviolet" should redirect to "ultraviolet light" as the (probably) far more common search result, but the wealth of this information on the page should be at "ultraviolet light" or perhaps "ultraviolet (light)". Banaticus (talk) 10:38, 29 December 2010 (UTC)

• Oppose subdividing the meaning in this way is totally unnecessary, the page can be on everything ultraviolet. Graeme Bartlett (talk) 11:49, 29 December 2010 (UTC)
• Oppose: the proposer seeks to differentiate between light at the "specific frequency" and "ultraviolet the color". This is unnecessary as there is no "color" (perception in the human eye and brain) ultraviolet. Apart from this quibble, as User:Graeme Bartlett. --Old Moonraker (talk) 12:05, 29 December 2010 (UTC)

Yes, there is perception in the eye (on the retina) and in the brain of ultraviolet. The problem is that the lens of the eye usually blocks such colors from being seen. People with Aphakia (who lack a lens in their eye for whatever reason, usually surgery to remove it because of congenital cataracts) can usually perceive ultraviolet colors. Banaticus (talk) 20:37, 29 December 2010 (UTC)

I didn't know that so thanks, but it now reads like a quibble of a quibble! Still not a reason to change. --Old Moonraker (talk) 21:08, 29 December 2010 (UTC)

Comment: I had overlooked the previous discussion on this topic, above, where this same point was made. The proposer accordingly withdrew his/her suggestion. --Old Moonraker (talk) 21:42, 29 December 2010 (UTC)

• Weak oppose per Graeme Bartlett. A. di M. (talk) 21:01, 29 December 2010 (UTC)
• Oppose Superfluous disambiguation. Also. Ultraviolet is not a specific frequency, but a frequency range. So, soft ultraviolet is one colour and hard ultraviolet another. Finally, notice that I haven't used the l-word^walk victor falk ^talk 06:13, 30 December 2010 (UTC)
• Oppose The article is already focused on the part of the electromagnetic spectrum commonly known as ultraviolet, which also the primary topic for the term. --Polaron | Talk 22:04, 30 December 2010 (UTC)
• Oppose There is not much usage of the term as a color, and if there were it should be included on this page. --Chetvorno^TALK 22:49, 30 December 2010 (UTC)
  • I agree that one or two paragraphs about the perception of UV by animals (including humans with aphakia) would definitely belong somewhere in this article. A. di M. (talk) 21:46, 1 January 2011 (UTC)
• Oppose That move is completely unnecessary, because a) There are no other articles called "Ultraviolet" and b) An article on the ultraviolet colour would be... inaccurate. -That Ol' Cheesy Dude (Talk to the hand!)

The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

/* Ultraviolet lasers */

I changed the link to Frequency conversion to Second-harmonic generation. Is "nonlinear optics#frequency mixing process" a better choice? It just gives a list of processes (including other frequency conversions). I directly linked to the SHG article because I think it was the most commonly used method. Some one please confirm /give a second opinion. Staticd (talk) 07:08, 2 February 2011 (UTC)

The article now links specifically to the commercial DPSS technology for this. —Patrug (talk) 10:35, 13 July 2014 (UTC)

Skin/harmful effects debate

There seems to be some conflicting information making its way into the sections on the human effects of UV radiation, especially the "Skin" section. The quote at the top of that section appears to have been chosen to specifically promote the point of view that there is no such thing as any amount of non-harmful exposure to the sun's UV radiation, although there is existing research to the contrary. I tagged it for NPOV. Also, some of the information seems amateurishly written by someone having little understanding of the properties of UV radiation or biology, such as the sentence "Sunscreen prevents the direct DNA damage that causes sunburn." Darkest tree (talk) 00:25, 5 April 2011 (UTC)

I agree about the conflicting information, there are definitely some issues with that throughout this and a couple other related articles in that area.

However, the statement that "Sunscreen prevents the direct DNA damage that causes sunburn." is correct in that AFAIK sunburn is a result of direct (and not indirect) DNA damage (see the respective Wikipedia articles on the two topics, and on sun tanning). I clarified blockage of UVB to be the mechanism of sunburn prevention, but left the clarification tag as I don't fully understand your objection to the sentence. 74.209.9.147 (talk) 10:10, 28 August 2011 (UTC)

^ I'm not sure that is correct. I'm doing a Masters in Genetics at the moment, and I wouldn't think that DNA damage can *cause* sunburn. Surely that is temperature-related. UV damage to DNA can cause mutations in the DNA however, which can lead to cancer, among other things.. — Preceding unsigned comment added by 213.104.214.207 (talk) 16:43, 3 September 2011 (UTC)

^ A sunburn is not a burn per se: it is an inflammatory response that may, in part, be caused by DNA damage. UV-A can still induce erythema but at a much, much lower efficiency compared to UV-B (I'm sure there's a copy of the erythema action spectrum somewhere around here). — Preceding unsigned comment added by 142.21.244.90 (talk) 18:13, 29 September 2011 (UTC)

I am adding some information and will be removing the tag for several reasons,

• 1)- "seems to be some conflicting information" is not justification for a tag,
• 2)- "I'm not sure that is correct", warrants research not tags,
• 3)- Leaving the tag because, "I don't fully understand your objection", with no further comments or edits from either side, infers the issue was resolved, and most importantly, that apparently escaped observation, is that;
• 4)- the mentioned "Skin" section is not a section, nor a subsection, but a sub-subsection of the section Human health-related effects of UV radiation, following the subsection "Beneficial effects" so is in fact also subsections that adds neutrality.

The only thing I have a masters in is marriage, after 34 years, but I am not crazy about those that may be deemed (self-deemed or otherwise) to be smarter than other editors using condescending writing, "seems amateurishly written by someone having little understanding", that might in effect drive off otherwise good editors. I am not trying to cause problems but call certain facts to light that I hope will be at least entertained. I am sure there was no malfeasance intended but if it is looked at from another perspective it can be viewed as such. I will be looking at this, and several related articles, with amateurish knowledge of the subject but a possible ability to research and tie some things together. If those that actually do have more knowledge would like to keep an eye on things (any of my edits), with a neutral (as well as none condescending) editorial approach, I would appreciate it. Otr500 (talk) 13:18, 18 October 2011 (UTC)

Ref60

The reference for #60 points to the wrong article. — Preceding unsigned comment added by 192.133.129.4 (talk) 22:08, 29 April 2012 (UTC)

So it does, thank you. Fixed it by simply removing the URL and letting the link be filled in automatically from the metadata. LightYear (talk) 04:35, 30 April 2012 (UTC)

UV-sensitive

Security section talks about UV-sensitive inks etc - can we clarify that this means UV-Fluorescent ? - Rod57 (talk) 01:14, 24 August 2012 (UTC)

Yes. The section now includes this. —Patrug (talk) 15:22, 11 July 2014 (UTC)

Extreme UV

Why is it that Extreme UV redirects here, but Extreme ultraviolet takes you to its own article?—Kelvinsong (talk) 02:12, 29 December 2012 (UTC)

An error. Perhaps the Extreme ultraviolet article didn't exist when the redirect was made. I'd go fix the Extreme UV direct so it DID redirect to Extreme ultraviolet, but this redirect has been done at some level where I can't get to it. Perhaps some superduper admin redirect or something. But I can't get to the page. Anybody know how this happens? SBHarris 02:33, 29 December 2012 (UTC)

I think it's fixed now Azylber (talk) 04:25, 29 December 2012 (UTC)

UV-A, UV-B and UV-C

UV-A, UV-B and UV-C redirect here, but are not explained at all. Presumably there was a discussion at some stage to merge these articles, but the merge never went ahead, only a simple redirect? Aarghdvaark (talk) 10:24, 28 April 2013 (UTC)

Actually found them in "Subtypes", but as UVA, UVB, UVC - not the usual abbreviation? (see e.g. the figure by the side of "Sources" which uses UV-A etc.) Aarghdvaark (talk) 10:32, 28 April 2013 (UTC)

The abbrevations used in the table come from the cited reference, if we want to change them we need another source (source of information, not of UV ;-). There's actually quite a number of redirects, many of which I now changed to link to Subtypes. — HHHIPPO 12:03, 28 April 2013 (UTC)

Visibility

Considering that we have an article entitled Cosmic_ray_visual_phenomena and our article on X-rays has a section on their visibility (X-ray#Visibility) it seems that we ought to have something about human ablity to see uv. Obviously most people don't see uv under most circumstances, but nowadays many people have access to exotic light sources such as ultraviolet and infrared lasers, diodes, lamps with expensive filters, monochrometers, etc. As a result, people have been seeing uv since about the mid-19th century, when Helmholtz et al conducted the earliest uv vision experiments. Furthermore, the CIE tables for both photopic (color) and scotopic (night) vision extend down to 360nm and 380nm respectively, even though these table are intended to describe what people see under normal conditions.

Admittedly there hasn't been a huge amount of research on this, but some. For example, the transmittance of the ocular media down to about the high 200s is well-characterized. Transmittance takes into account such factors are opacity, reflection, refraction, and scattering. The ocular media include the cornea, lens, aqueous humor, vitreous humor, retinal ganglia, and in the case of foveal vision, the foveal aperture.

Aphakics (people missing a lens in at least one eye) have been documented at seeing uv down to 250nm, but only scotopically, and only under ideal laboratory conditions of the sort found in vision experiments. Normal children and young adults have some color perception and visual acuity down to about 315nm, with light perception documented as far down as 300nm, with the occasional rare individual being able to perceive light as far down as 280nm.

At some point between 390nm and 405nm (usually between 395nm and 400nm) the color begins to change from violet to desaturated blue. There is a local desaturation peak at 377nm, but not a sharp peak: high desaturation extends for quite some distance in either direction. At or near 377m, uv looks almost white. At 350nm there is an local saturation peak making uv look blue at middle and high intensities, violet at low intensities. Below 350nm desaturation increased so that by 335nm color is faint, by 315nm nearly extinct. The cause of the desaturation is unknown, although nearly all forms of eye fluorescence have been ruled out.

Visual acuity declines due to eye fluorescence starting in the high 400s. At about 460nm it is not intense enough to be consciously noted, but adversely affects reading contrast. In other words, eye fluorescence is not just a problem in the ultraviolet. Between 420nm and 380nm it increases markedly, making things look fuzzy. The eye contains many fluorescent proteins and other substances, each with their own activation and emission wavelengths, making it difficult to make broad generalizations, but at lower wavelengths eye fluorescence is not as big an issue as some might expect. In other words, one can't just extrapolate from the sharp increase that occurs between 420nm and 380nm since it doesn't work that way.

The elderly generally cannot see uv. People of middle years are all over the map, and not just as a function of age. Zyxwv99 (talk) 14:56, 19 September 2013 (UTC)

The article now includes a bit of this. —Patrug (talk) 15:22, 11 July 2014 (UTC)

correction needed

In the section 'sanitary compliance' the following comment needs revision: '...Ultraviolet light aid in the detection of organic mineral deposits...' Minerals by definition are abiogenic. Organic minerals do exist, but are rare at best. The idea of searching for organic minerals for sanitary compliance is silly. — Preceding unsigned comment added by 70.171.44.124 (talk) 13:49, 31 October 2013 (UTC)

Probably a misspelling for "material." Will fix. SBHarris 00:20, 1 November 2013 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Ultraviolet/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

I was looking for frequency ranges for the three UV bands. The article mentions the band, but does not authoritatively link the band names to the wavelengths. —66.83.109.202 18:32, 27 February 2007‎ The article now includes details of UVA, UVB, UVC. Future comments will be seen more quickly if posted directly to Talk:Ultraviolet. —Patrug (talk) 08:58, 13 July 2014 (UTC)

Last edited at 08:58, 13 July 2014 (UTC). Substituted at 20:56, 4 May 2016 (UTC)