Talk:Scanning electron microscope

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Ant picture broken?[edit]

I don't think there's anything wrong with the formatting of the page, it'd show the image if the image existed - I get a 404 not found message when I try to look at the image directly. I guess the image needs to be uploaded to Wikipedia again. Average Earthman 15:59, 5 Aug 2004 (UTC)

That's pretty odd though. What do you think could cause that to happen? -- TomPreuss 13:03, 6 Aug 2004 (UTC)

Scanning Electron Microscope = SEM[edit]

Shouldn't this page be listed under SEM? It's a pretty common abbreviation. --Michaeltoe 22:09, 4 Feb 2005 (UTC)

Why does the paragraph end abruptly?[edit]

The use of a dedicated backscattered electron detector above the sample in a "doughnut" type arrangement, with the

That is all: the paragraph in the section 'Detection of backscattered electrons' ends abruptly. Seems like there's some half-editing... I can now see the paragraph fully, and no one has edited it!! Perhaps there was a problem in the browser I was using(in my college). Firefox proves itself to be THE best. :)

SundarKanna 20:03, 26 December 2005 (UTC)

  • The rest of that paragraph had lost in a revert some time ago. I put the missing section back in yesterday. eaolson 21:08, 26 December 2005 (UTC)

The French article is no more featured[edit]

I removed the template {{FAOL|French|fr:Microscopie électronique à balayage}} because the French article lost its featured article status. Stefane 07:47, 21 March 2006 (UTC)

Secondary Electron Confusion[edit]

What are secondary electrons? What does "escape" mean? Why do they "escape"? This section does not stand on its own, but relies on a careful reading of other sections. While I made some changes due to style and grammar in this section, I am still confused by its content. I don't want to change the article itself because of my lack of knowledge, but here is what I think it is trying to say. I have heavily interpreted what I read and even made educated guesses. Can anyone confirm/disconfirm my guesswork?

"An electron beam rasters (i.e. scans back and forth) over the surface of a material, which absorbs the energy. The material re-emits secondary electrons in every direction. An electron sensor known as a scintillator-photomultiplier, measures the intensity of the secondary electrons and converts it into a two-dimensional image with bright and dim regions. The most common imaging technique detects low energy (<50 eV) secondary electrons originating a few nanometers from the surface.

The brightness depends on the angle of the surface. If the beam is perpendicular to the surface, then the spotlighted region is as small as possible, which minimizes the number of electrons that escape. As the surface angle increases, the spotlighted area increases, and more secondary electrons will be emitted. Steep surfaces and edges appear brighter than flat surfaces, resulting in well-defined, three-dimensional images. This technique makes resolutions of less than 1 nm possible." —The preceding unsigned comment was added by Dhskep (talkcontribs) 2006-04-06 05:11:22 (UTC).

There surely is an error in the section as it is writing in the post right now; "As the angle of incidence increases, the "escape" distance of one side of the beam will decrease, and more secondary electrons will be emitted." This "ecape distance" must increase with angle and secondary atoms emitted.

But you version without escape distance is certainly much more eatable then the current. —Preceding unsigned comment added by Nanopete (talkcontribs) 22:16, August 25, 2007 (UTC)

Anybody who knows about SEMs?[edit]

I came across an orphan about OIM (apparently stands for orientation imaging microscopy). Can some one try to verify the information in it? Here: Orientation imaging microscopy (which is where I had to move it to make way for an "OIM" disambiguation page. — User:Donama 04:33, 17 May 2006 (UTC)

Construction[edit]

Can somebody give me the construction and the electronics involved in electron microscopy? —Preceding unsigned comment added by 220.225.87.34 (talkcontribs) 06:25, 11 June 2007 (UTC)

It consists of an electron gun commonly made of tungsten and cathode because of its high melting point.a grid is placed nearer to the electron gun which is used to accelerate the primary eletrons.a magnetic condensor lens and scanning coils is placed nearer to the grid .sample is placed next to the scanning coil a collector is followed by a video amplifier and cro .the scanning coil is connected to the cro and it is then connected to the scan generator. —Preceding unsigned comment added by 117.193.98.168 (talkcontribs) 02:19, 17 November 2009 (UTC)

References to be amended[edit]

The reference to Alan Nelson's patent is irrelevant as there has never been any implementation of this approach to an environmental SEM either in laboratory equipment

or in commercial instruments, and no published reference to a refereed journal exists. In contrast, the patent:

U.S. Patent No. 4,823,006, filed Feb. 19, 1988. Integrated electron optical/differential pumping imaging signal detection system for an environmental scanning electron microscope. Inventors: G.D. Danilatos, G.C. Lewis. Assignee: ElectroScan Corporation.

describes the first commercial ESEM imlementation by ElectroScan. The latter was based on prior Danilatos works as listed in http://www.danilatos.com. In addition to the differential pumping and electron detection techniques described by the first Danilatos reference provided in the present entry, the commercial ESEM has made extensive use of the newly invented system of a gaseous detection device as comprehensively described by:

Danilatos, G.D. (1990). Theory of the Gaseous Detector Device in the ESEM in Advances in Electronics and Electron Physics, Academic Press, Vol. 78:1-102.

The Alan Nelson patent inappropriately employs a series of apertures with trapped air in the cavities between them. As a result, the electron beam would suffer significant losses before it can be usefully employed in the specimen chamber. At any rate, Alan Nelson by no means should be referenced as a contributor to the development of ESEM, let alone as an initiator of this technology. In contrast, Danilatos preceded with his first patent and papers on ESEM in 1979. It is therefore proposed to amend the references accordingly.

Esem0 05:40, 8 July 2007 (UTC) Esem0 05:43, 8 July 2007 (UTC) Esem0 05:45, 8 July 2007 (UTC)


Esem0 04:11, 10 July 2007 (UTC) Esem0 04:12, 10 July 2007 (UTC)

Depth of Field[edit]

I've been looking through some of the imaging articles, and many appear to be missing major concepts fundamental to the instrument. For example, SEMs are known for their amazing depth of field, yet this term is not used at all in this article. Is there something I don't know about SEMs or Wikipedia and imaging articles that is a reason for omitting this?

KP Botany 02:06, 4 October 2007 (UTC)

it would be very nice if resource for downloadable SEM images also put here[edit]

it would be very nice if resource for downloadable SEM images On an archived bundle (such as rar or zip) also put here as the resource for people yo get Free SEM images on a specific category, such as human cells or parasitology Etc.

ive been looking anywhere to get such resource, and nothing better than here. But i wish a can find The free image bundled as i mention. —Preceding unsigned comment added by Kuplukjaya (talkcontribs) 07:06, 25 March 2008 (UTC) Kuplukjaya (talk) 07:13, 25 March 2008 (UTC)

Removed content[edit]

This edit changed a fair bit of text, and seems to have removed some info, as well as adding some. Can someone look at this? Should it simply be reverted? —Pengo 01:11, 30 March 2008 (UTC)

Removed images from gallery.[edit]

There are many poor quality SEM images on Wikipedia for some reason. I removed some from the gallery for this article, because there are a sufficient number of better quality or useful images. The one of the topo/atomic number contrast should also be removed when a better image comes up.

The first one I removed is of the polyester. This image has serious charging artifacts, creating the ruinous line across the middle of the image, it's in focus almost nowhere, and it has lousy depth of field (of course, since it's in focus almost nowhere). A longer working distance, a smaller aperture, a smaller probe size, lower KV, better coating, many things would have made this a better image. It's fine for the polyester fiber article for now, but a better one should be captured or found, as this one has too many problems with it to be used in an encyclopedia for anything other than an article on SEM artifacts (which it would be good for).

The diatoms are out of focus. There's no point to the image. It's not in focus anywhere in the depth of focus of the image.

The red blood cells should be removed also, when they can be replaced with a better image. Red blood cells are easy to shoot on an SEM, and this image is far too noisy to be considered for production anywhere outside of Wikipedia--it's too old. However, because red blood cells look totally cool on SEM (versus TEM), it's okay to leave this very noisy image in for now. They're a standard.

The nematocyst is too low resolution to be of any use. It should be replaced, also.

The Drosophila melanogaster body is very poorly preserved, rather than life-like, there's excessive charging to the point of putting a bright white lightening bolt through the image, and the carbon dag substrate consumes an unwieldy portion of the image. However, this is a basic subject in SEM, like red blood cells. Its compound eye is completely out of focus, also.

The asbestos fibers should be photoshopped to remove the charging artifacts, if left in. The picture is not compelling or illustrative of anything other than the fact that SEM is used to look at asbestos fibres. I think it is rather common.

Probably the same public domain sources could be searched for better images.

An SEM image should be in focus. This does not require an expert microscopist to discern. It's either in focus or it's not. TEM images can be much more subjective and demanding of expert eyes to tell quality. Especially with biological specimens, if it looks out of focus, if the insect is collapsed and dessicated, it's not a good image. It's more difficult with materials specimens, but there are few of any of these of any quality on Wikipedia.

--Blechnic (talk) 06:27, 8 April 2008 (UTC)

Then you should replace rather than remove if you are concerned about image quality. Otherwise you are depriving readers of information. Peterlewis (talk) 06:36, 8 April 2008 (UTC)
Precisely what information have I deprived anyone of by removing an unacceptable micrograph? Can I upload pictures of my cat and use it, no matter how low quality, in the article on cats? No. The same thing should not be acceptable with micrographs. I left plenty of bad ones without leaving the worthless in the article. They contain no information without pointing out to the readers that they are useless due to artifacts which render them of too low quality to be proper micrographs. --Blechnic (talk) 06:51, 8 April 2008 (UTC)
PS In addition, people with good micrographs may just see an overly full gallery. They won't want to add good images in with the low quality ones, or they may not even look beyond the number of micrographs, thinking Wikipedia is full of SEM images. It's not. --Blechnic (talk) 06:53, 8 April 2008 (UTC)

Additional question on images. Does someone have the original source material for the photoresist? It says it is taken at 1KV, it also has "standing waves" and "DSM" on the bottom. 1 KV is very unusual for SEM, so it should be elaborated in the caption. --Blechnic (talk) 07:01, 8 April 2008 (UTC)

I think you are being over-critical. I am a microscopist myself, and would be happy to use any of the images you deleted. If you have better ones or more showing other details, then put them in. But you cannot just delete what is already there. Peterlewis (talk) 07:06, 8 April 2008 (UTC)
Yes, if the images are completely unworthy due to artifacts that could not be published, they should be removed. I am skeptical that you are a microscopist and would leave an image like that of the blurry, out of focus, no depth of field polyester with all the charging and a charging artifact slicing the image almost in half top to bottom, the blown out asbestos, the flattened flies, the out of focus diatoms. Leaving junk in is an invitation not to find much better. Especially compared to the newer micrographs. There are plenty of images left in the gallery that leaving the junk in is not necessary. --Blechnic (talk) 07:10, 8 April 2008 (UTC)
SEMexample.jpg

This image is in focus in over less than 10% of the picture. It has no depth of field--it might as well have been shot on a light microscope. It has ugly charging artifacts. The substrate (cracked dag?) is hideous. The information on the bottom shows what went wrong: too short a depth of field, too high a KV, add the blown out areas, and the charging artifacts and you wind up with not much worth sharing. Just because it's a secondary electron micrograph doesn't mean it has to be on Wikipedia. --Blechnic (talk) 07:16, 8 April 2008 (UTC)

Image quality[edit]

Well, stop moaning about images and replace the ones you object to with your own. I have been using SEM, ESEM and OM for many years and live with the problems you mention. If only we all lived in a perfect world! Perhaps you should write a new article on "artefacts in SEM". Peterlewis (talk) 08:07, 8 April 2008 (UTC)

I'm not sure how much value it would be to a general encyclopedia. I get images all of the time with charging, edge effect, out of focus, not enough depth of field, too low in contrast. But I shoot them over if I need them to illustrate a point. I don't publish them for the whole world as an example of an electron micrograph. That's the difference, here, and it's an important one. I'm not moaning about the images. I stated precisely why I removed the ones I did, why I left the ones I did, and why the removed ones should not stay in the article. This is not "moaning," it is a courtesy to other readers to explain what is going on. I also elaborated to you when you asked. --Blechnic (talk) 09:11, 8 April 2008 (UTC)
You should be more positive, and put some of your pics into the article before deleting the work of others. The present set (which I have restored) are quite acceptable in my opinion for the general reader. However, what you could do is to add comments about charging and lack of focus etc as a separate section, and then show them how to eliminate such defects if they are interested in the finer detail. Peterlewis (talk) 09:25, 8 April 2008 (UTC)
So, explaining how bad they are would satisfy you? How would that enhance the article? Is that standard for Wikipedia, that you include bad pictures that poorly illustrate a point, then explain what's so bad about them? Why have so many pictures, if so many of them are bad? Well, suit yourself, I'll label them why they're garbage. --Blechnic (talk) 09:28, 8 April 2008 (UTC)
Okay, I labeled them as junk. I'll see what other junk I can upload to the gallery, since it seems, that having a few quality images is a bad thing when one can have a ton of images that do nothing to enhance the article, are low quality, barely show what they are supposed to show, and simply waste band width. But you're the microscopist. Silly of me to think one quality image could show as much as three junk shots. --Blechnic (talk) 09:38, 8 April 2008 (UTC)
Look, I've stumbled across this talk page by chance after having a disagreement with you on featured picture candidates, and I can see quite clearly that you have a very poor attitude and a stubbornness that makes it difficult for you to appreciate any other point of view, looking down on those you disagree with. I'm no expert on SEM, but I do agree with Peterlewis that until better images are procured, either by yourself or others, there is no harm in keeping existing ones that illustrate unique subjects. As he mentioned, sure, comment on what could have been done better if you think it would benefit the article, but the article is not just for experts, and it is quite likely that laymen wouldn't even appreciate or care how bad the images are, technically.
Ultimately though, why not just improve on the images rather than remove them and complain about how horrible they are? Diliff | (Talk) (Contribs) 22:32, 10 April 2008 (UTC)

My "attitude" and "stubborness?" Are we discussing the article or attacking me personally? I look down on those I disagree with? Where's your proof of that? I'm too short. There is no need to put any crappy image on Wikipedia for any reason. It's not a dumping or holding ground for garbage, particularly when the gallery can be filled nicely with a smaller but sufficient number of SEM micrographs that actually show something. If you wish to discuss me and your guesses about me personally and attack me personally find somewhere and some way else to do it. This is a discussion page for the SEM article. The article was improved by removing the images, rather than by littering it with crap by keeping the images in. The existing ones do not illustrate unique subjects. I left the ones that do this in. The article doesn't have to be for experts to show a decent SEM micrograph. That is the beauty of an SEM, even non-experts can look at a beautiful micrograph, like the ones of the arthropod eyes, and tell they are beautiful and without the artifacts of bad micrographs. Littering Wikipedia with crap in articles simply because someone uploaded it isn't writing an encyclopedia. Peter Lewis insists the crap must stay, so it should be identified as crap. In my opinion a smaller gallery of a well-chosen variety of good images would be a much better choice, but Peter Lewis wants the bad micrographs, so I agreed to allow them with the captions. How about I divide the gallery in two? Example electron micrographs and trash? Get off the topic of me. --Blechnic (talk) 04:44, 11 April 2008 (UTC)

This, right here, is a nice gallery of notable, good, or example electron micrographs:

Adding garbage to the article, simply because it exists on Wikipedia, does not make this a better article, or a better gallery. It is just poor quality, unpublishable, micrographs. Why publish them on Wikipedia? Is this a dumping ground for bad snapshots? No, this is an encyclopedia article. More is not better, when the more is without additive value. Adding poor quality micrographs that fail to illustrate anything but their own poor quality is not necessary for an article on SEM. I bet the photography and camera articles don't have example trash images in their galleries. It's absurd. --Blechnic (talk) 04:51, 11 April 2008 (UTC)

Peterlewis is right: If Blechnic knows so well what constitutes good SEM images, then certainly he should be in a position to supply them too. Instead, he just repeats the words "crap" and the like without making any step forward. Removing the images is a step backward, and I can see no harm to the reader for the purposes of this very short entry. I think Blechnic should put up or quit arguing. It's absurd, indeed. I have been working in the field for 30 years. Thank you.

There's no need to put up or shut up anything. The gallery is a discrete, usable gallery of a variety of SEM images, each with a purpose. There's no need to litter any Wikipedia article with crap, just because crap is available, as there is no end to available crummy micrographs. I'm not impressed with you working in the industry for 30 years if you see a need to keep a poorly captured, out of focus throughout entire image, micrograph in an article. Over 30 years you should have seen thousands of far better micrographs and no need whatsoever to keep an amateurish one anywhere, much less give it prominent in an encyclopedia article. Wikipedia is the only encyclopedia featuring bad micrographs. --Blechnic (talk) 20:10, 13 April 2008 (UTC)
I won't comment on the quality of the images, but I would say that I'd feel the aim of the gallery would be to show the whole range of capability of the SEM, rather than contain a large number of images of a similar type (e.g. secondary electron images of parts of insects). As such, a lower quality image that illustrates a different application could be preferable to a very good image of a type of which we have more than one example already. DrMikeF (talk) 10:33, 7 August 2008 (UTC)

Image captions[edit]

Re the caption on the photoresist about the semiconductor industry: the purpose of mentioning their importance in the industry is that the image is of a semiconductor photoresist. Yes, they're important (high res FE guns) in many industries, but these are just notes about the particular images in the gallery, so the high res comment is specific to this excellent micrograph. --Blechnic (talk) 20:10, 13 April 2008 (UTC)

Removed sections[edit]

"Gold coating may be regarded as a semi-destructive process since removal of a gold coating requires aggressive chemicals such as potassium cyanide or aqua regia, although this would only be required in practise if a specimen has high intrinsic value, as in an archaeological artefact."

Is there an example of a museum coating an archaeological artefact with "high intrinsic value" then using arsenic of something to remove the gold? I pretty much only work with natural history specimens, often type specimens, so coating is simply not done, so it's hard to imagine damaging a precious specimen by coating it to capture an image. An example would go a long way for this sentence.

In 30 year's work with SEMs I have only very rarely encountered a requirement to uncoat a specimen. It can be done, however, though using arsenic you'll probably not get very far.Plantsurfer (talk) 08:27, 23 April 2008 (UTC)
Then let's remove this statement entirely. It's weird. I've uncoated a few specimens, but never archaelogical museum specimens. --Blechnic (talk) 16:53, 23 April 2008 (UTC)
Go on then, why don't you?Plantsurfer (talk) 17:02, 23 April 2008 (UTC)

Also, I thought "Environmental SEM" was a trademarked name? If so, should we be using it generically in an encyclopedia, or does this matter?

"Working with the method is easier because the sample chamber is very large, and control is usually completely computer controlled."

Always very large? I just visited a lab today with an old Zeiss SEM (tungsten filament) that has a huge sample chamber. The variable vacuum SEM I use has a pretty big sample chamber, but it's not huge compared to my other SEMs. And, "completely computer controlled" is not a function of low vacuum variable pressure SEMs, it's a function of what you ordered when you buy it. It's conceptually new so it comes with a computer interface, but the cheaper versions can come with mechanical controls if you're an institution with a finite budget and a high need.

"Coating is thus unnecessary, and X-ray analysis unhindered. Sample manipulation within the specimen chamber is always more difficult than in optical microscopy, however, and colour rendition is absent."

Huh? Why do we go to comparing an environmental SEMs chamber manipulation with that of a light microscope? Is it easier in a conventional SEM. And, no, it's not "always more difficult than in optical microscopy!" It depends upon the optical microscope and the SEM. Last week it took me all day to set up some light microscope images and half an hour to shoot a few dozen high resolution bacterial images on an SEM, mostly because of the time spent aligning the optical microscope's stage for collecting data.\

"Colour rendition is absent" in an environmental SEM? Well, why would anyone use them if they can't get color? It's also absent in all electron microscopy. This section needs to be about the ESEM, not just filled with general information to make it thicker. Maybe it was just copied from another article merged with this?

I'm beginning to think someone writing this article is selling or investing in ESEMs. However, it's not necessarily to internally link every occurrence to its section in this article. People will still buy them without the excessive linking.

--Blechnic (talk) 02:40, 23 April 2008 (UTC)

excellent, there was a lot of POV in those sections Plantsurfer (talk) 08:27, 23 April 2008 (UTC)

Indeed, the removal of gold-coating is such a minute detail in the big picture of SEM, weird to have it here. I agree that the link of ESEM to FEI company should be deleted. They do not have the monopoly of it any more. However, the name of ElectroScan should remain as it is historically important. The names ESEM and Environmental SEM are generic terms in use for about three decades long before ElectroScan claimed it as a trademark (this term was actually first introduced by Danilatos in 1980). Therefore, the fact that a commercial company successfully but "unlawfully" managed to trademark it for some time has created a misconception which should not be allowed to leave a permanent imprint in the encyclopedia. Commercialism should be struck out. If you were to delete ESEM, then what else is there to replace it with? Perhaps, VPSEM which is used by a competitor to FEI to also promote ESEM (who use ESEM as generic term in their brochures); or "Wet-SEM" adopted yet by another competitor? Or "Natural SEM" by another one, or "Bio-SEM" once used by AMRAY? The encyclopedia should not be trapped by any on these commercialisms with their corresponding catchwords. However, ESEM is an independent generic term naturally evolved from academic research. Manufacturers have unfortunately created a lot of confusion around, and many workers in the field have been misled. It would be nice if all involved in this subject took some time to study the relevant literature. There are many misconceptions around and things should be cleared once and for all. This forum is a good place to start. Please comment before action is taken to make the change - or the first proposer (or other) proceed to make it. Esem0 (talk) 00:44, 26 April 2008 (UTC)

Thanks for the lecture, but the question does remain. Is it a trademarked term? Or not?
This is not really a forum, and not the place to disabuse folks of misconceptions about nomenclature usage in the field of scanning electron microscopy, it's simply the discussion page for this article.
It is however useful to discuss and agree upon actions before making changes, like discussing a general outline for this article. It would be very useful.
However, this is also not an article about environmental SEMs, and there was simply too much about it in the article, and the same information repeated over and over, in in appropriate places, often. I, by the way, don't call VP SEMs "environmental SEMs," simply because I've gotten into the habit of reserving that term for the one tabletop SEM, and call the VP SEM a VP SEM or a low pressure SEM, usually based upon what I'm using it for, although it's mostly used as just another regular SEM.
I asked the question about the trademarked term because there should be an article on ESEMs in general, to which much of this excess can go, and the question needs cleared up before picking a title for that article. --Blechnic (talk) 01:22, 26 April 2008 (UTC)

The trademark ESEM is dead since March 22, 1999, according to US Patent and Trademark survey (something you could have done yourself, if you wanted to really contribute). Therefore, ESEM is not a trademark, it is generic per previous statement. I thought my comments would be in agreement with you and that I was following up with your request, but you seem to be pleased with nothing. Please make an effort to be constructive and stop picking on issues or persons that don't deserve your aggressiveness. Just consent for once. Esem0 (talk) 02:42, 26 April 2008 (UTC)

You ask no question that requires my consent or non-consent. Instead, without specifically answering the question about the trademark, you ask what it would be replaced with if ESEM is not used. The question of the trademark is critical to answering this question. If it's no longer trademarked there is no need to ask or answer the question. As you asked the question, I assumed your answer meant the trademark still existed.
It's also hard not to be a bit aggressive considering how strong the fight was to keep a gallery of crappy useless micrographs in this article. And it puts this article on an uncertain level as far as editing goes, making it difficult to know what is going on with the article, and making it easy to make assumptions about how it wound up in its current state. I should have received strong support from microscopists for removing bad micrographs, but got nothing but arguments. The gallery is much better without the garbage.
But let's focus on issues concerning the article and stop trying to patronize me. Thanks.
--Blechnic (talk) 03:45, 26 April 2008 (UTC)

Objective lenses in SEM[edit]

SEMs don't have objective lenses. The signals from the object are collected by various detectors and images formed from the detection of these signals not from the final lens. The final lens or focusing lens is not an objective lens. --Blechnic (talk) 02:53, 23 April 2008 (UTC)

Good point. An SEM's objective lens is for focussing the beam. Provided the column can generate a beam with sufficiently small diameter, an SEM could in principle work entirely without condenser or objective lenses, although it might not be very versatile or achieve very high resolution. One might also mention that, unlike optical and transmission electron microscopes, magnification in the SEM is not a function of the power of the objective lens. It results from the ratio of the dimensions of the raster on the specimen and the raster on the display device. Assuming you are working with a fixed size display, higher magnification results from reducing the size of the raster at the specimen, and vice versa. The x,y scanning coils therefore control magnification, not the objective lens.Plantsurfer (talk) 08:27, 23 April 2008 (UTC)
Add it to the article, don't tell me back here! However, this whole area of how the microscope work needs developed, so I'm not certain if it wouldn't be better to outline a battle plan rather than piecemeal fixing things. --Blechnic (talk) 16:47, 23 April 2008 (UTC)

Formaldehyde is not used in EM, paraformaldehyde is; spelling properties[edit]

Find a source that shows otherwise, rather than your original resource into properties of formaldehyde. I thought you did EM? This is a strange edit for someone who actually does EM. Where exactly are you getting this information from?

There is no need to keep your incorrect spelling of proprties, whatever the decision about formaldehyde/paraformaldehyde.

--Blechnic (talk) 02:03, 20 July 2008 (UTC)

Blechnic, you are completely up the creek about this I am afraid. Paraformaldehyde is a polymerized form of formaldehyde that is used to make very pure formaldehyde solutions by heating in water to 60oC with a small amount of KOH or NaOH. I repeat, paraformaldehyde (=polyacetal) is INSOLUBLE in pure water at STP. It decomposes very slowly to formaldehyde, hence a slight formaldehyde smell, but will not fix specimens as paraformaldehyde. To be effective as a fixative, paraformaldehyde needs to be decomposed completely to formaldehyde, HCHO. To be pedantic, in the words of [1] formaldehyde dissolves in water to form methylene hydrate HO-CH
2
-OH
.
Karnovsky first published the use of a glutaraldehyde/formaldehyde fixative in 1965 made by depolymerization of paraformaldehyde[2] and plant scientists around the world use this, or variants of it with different buffers, concentrations of GA, FA routinely. My lab uses it as the standard fix, and I have used it routinely all my working life for SEM, TEM, LM, you name it.
see also[3] and the following link and Karnovsky's original paper for more background

http://library.med.utah.edu/WebPath/HISTHTML/MANUALS/KARNOV.PDF

Kiernan's paper is reproduced at: http://publish.uwo.ca/~jkiernan/formglut.htm

For a bit of background on properties of paraformaldehyde please look at the Wikipedia page on it.

Plantsurfer (talk) 09:18, 20 July 2008 (UTC)

You didn't read these at all, did you?

Why not go ahead and read what you just linked to, an article about using paraformaldehyde (Karnovsky's, something I've used a lot and not much changed from the original), that doesn't mention formaldehyde at all, and an article about why commercial formaldehyde is not used, but how it is

"the regular practice for at least 35 years has been simply to heat the paraformaldehyde to 60C in water containing the salts used to buffer the solution to pH 7.2 to 7.6. "

or

"A solution of formaldehyde prepared from paraformaldehyde, which does not initially contain any methanol, is commonly used in fixatives for electron microscopy and in research applications. Satisfactory ultrastructural preservation is, however, also seen in tissues fixed in buffered formaldehyde generated from formalin (Carson, et al., 1973)."

So, back to the original request. A reference that you can cite that lists formaldehyde as the fixative of choice, go for the regular commercial grade, also, to explain why it is used. Rather than your own OR from sources that contradict what you say and that you appear to have not read. --Blechnic (talk) 09:43, 20 July 2008 (UTC)

Yes that is the critical bit in Carson et al.: "formaldehyde PREPARED FROM paraformaldehyde". Your accusation that I have not read the sources is a case of the pot calling the kettle black. Please read the references I have provided and understand them before continuing to troll me on this.Plantsurfer (talk) 10:24, 20 July 2008 (UTC)
Yes, that is what is used, "formaldehyde," and guess what, all of the other chemicals, like the buffers, and everything, are also prepared. Do you do any EM? Do you sit and mix glut with formaldehyde to do your speciment prep? "A solution of formaldehyde prepared from paraformaldehyde, which does not initially contain any methanol, is commonly used in fixatives for electron microscopy and in research applications." from a 1973 source. Surely there's a book that shows that formaldehyde is the choice. Interesting enough, "that does not contain any methanol," the whole reason behind it is completely ignored by you and not quotes. Again, please just find a book that says this rather than providing your own EM views. That's what I use, books. Not OR. So, quote what you say, rather than conveniently breaking it off to match what your OR says. --Blechnic (talk) 19:51, 20 July 2008 (UTC)
PS Please don't revert me, provide sources that prove my version, then tell me not to revert, after you've provided the references to my edits. What is the deal, anyway with Wikipedia and this Original Research frenzy? --Blechnic (talk) 09:45, 20 July 2008 (UTC)
What on earth are you talking about?Plantsurfer (talk) 10:24, 20 July 2008 (UTC)
Oh, you didn't revert me? Confirm this, and I will report that your account has been hijacked, since, you don't seem to know what you are talking about. This could explain the formaldehyde issue, also, though. --Blechnic (talk) 19:45, 20 July 2008 (UTC)
And the citecheck stays as long as what is in the article, paraformaldehyde, isn't mentioned in the reference you want to use. Your original research call isn't citable. --Blechnic (talk) 19:47, 20 July 2008 (UTC)

A single 1985 article on fixing plants? Well, I'll get a copy and read it. It better say that "formaldehyde" is the one of choice. You can't use one of your textbooks? I'll be sure to check mine. Heck, the article's by Russell, is this what he says in his textbook, which is later than 1985? --Blechnic (talk) 15:15, 21 July 2008 (UTC)

I would have used one of my books, but that would contravene WP:OR  ;)

Plantsurfer (talk) 15:56, 21 July 2008 (UTC)

Oh, it's in a book, not a journal. 1991? Well, please provide an exact page number, then, rather than 100 pages. --Blechnic (talk) 15:59, 21 July 2008 (UTC)
Contravene what? If you're a published author on EM then by all means use one of your books. I don't for one minute think that will be an issue, though. --Blechnic (talk) 15:59, 21 July 2008 (UTC)

References[edit]

  1. ^ Kiernan JA (2000)Formaldehyde, formalin, paraformaldehyde and glutaraldehyde: What they are and what they do. Microscopy Today 00-1 pp. 8-12
  2. ^ Karnovsky, M.J. (1965). A formaldehyde-glutaraldehyde fixative of high osmolality for use in electron microscopy. Journal of Cell Biology 27: 137A-138A.
  3. ^ Robards AW and Wilson AJ, eds (1993)Protocols in Electron Microscopy. John Wiley and Sons.

Non-existent article?[edit]

The article cites Karnovsky, M. J. (1965). "A formaldehyde-glutaraldehyde fixative of high osmolality for use in electron microscopy". Journal of Cell Biology 27: 137A–138A. . However, I wasn't able to find this article in the journal's archive. Is there some mistake? ––Bender235 (talk) 09:23, 12 August 2008 (UTC)

The fact that it was published as an abstract may explain it. JCB's archive only lists the abstracts of full papers. You need to refer to the paper copy. Plantsurfer (talk) 09:51, 12 August 2008 (UTC)

May I draw your attention to the article Electron microprobe[edit]

It seems like the article Electron microprobe has substantial overlap with this one. In fact, between this article and the EDS article, I think almost everything in Electron microprobe is covered, but better. Should Electron microprobe be merged and then deleted? Or should we decide that parts of this article should be moved to Electron microprobe and vice-versa? I don't know, but I'm hoping someone here will do something about this. Thanks!! :-) --Steve (talk) 04:39, 30 January 2009 (UTC)

They are two different instruments, although they have entirely overlapping functions. The SEM is almost always equipped with EDS, but not always with WDS, while an EPMA always comes with multiple WDSs and an EDS. Also an EPMA has a light microscope integrated for focusing for the WDS. There are other differences, even though they can both accomplish pretty much the same things. The EPMA article needs a lot of work, but it is a specific instrument, with its own history, versus the SEM. Almost every geology department of a university will have an EPMA and a TEM. All of them want an SEM in addition, but not all of them have their own SEM. I don't think that EPMA should be deleted. Maybe parts of this article could be moved to EPMA, and a link to the main article on EPMA indicated at the top, with merely a couple of paragraphs here describing how the two instruments are closely related. --KP Botany (talk) 03:00, 31 January 2009 (UTC)

Snowflake[edit]

Did they have to coat the snowflake with gold before scanning? Would be nice to mention it in the caption since the coating-of-gold was a surprise to me when I visited this article. Tempshill (talk) 06:36, 7 February 2009 (UTC)

Yes. Bill Wergin used sputtered gold or platinum coatings on his snow/ice specimens. Plantsurfer (talk) 15:11, 7 February 2009 (UTC)
Thanks for asking the question, Tempshill. I added a note to the image caption for other readers. The snow crystals are usually captured on a cooled copper plate (-100 and something degrees C), then sputter coated with platinum in a cryo-sputter coater (for lack of a better name), then imaged in the cryo-SEM. --KP Botany (talk) 11:52, 8 February 2009 (UTC)

Micro or Nanometer Coating Thickness[edit]

I'm an amateur, but in my experience with gold or carbon sputter coating, the thickness is a few nanometers. In the "biological samples" section, it says: "However, the coating has a thickness of a few micrometres." I think this is a typo, but I'm unfamiliar with biological samples so I thought I'd check here before I changed it. Jermor (talk) 20:51, 19 February 2010 (UTC)

While I never worked with bio-samples either, the statement is certainly in error (micrometer coating would be intransparent; and all sources say nanometers), and thus I changed it to nm. Materialscientist (talk) 05:28, 20 February 2010 (UTC)

Another kind of SEM?[edit]

Is there also not in existence a transmission scanning electron microscope? If so, can someone more knowledgeable write upsomething about it? Old_Wombat (talk) 09:23, 28 October 2011 (UTC)

We have scanning transmission electron microscopy, but it does need much work. Materialscientist (talk) 09:41, 28 October 2011 (UTC)

Not knowing enough about the STEM to comment on the quality of the article, the only point I was trying to make is that the SEM article should have some kind of link/pointer to the STEM one. Old_Wombat (talk) 08:48, 30 October 2011 (UTC)

No colored pictures![edit]

I strongly believe all altered (MEANS COLORED) micrographs should be removed. — Preceding unsigned comment added by Vniizht (talkcontribs) 22:07, 3 February 2012 (UTC)

I'm also concerned that members of the public think SEM images come colored, and that the colors mean something important ("Oh, that cell is red, which told the researchers that it was cancer!"). Rather than remove them, however, I'd like to see a section on colored images, talking about how it is done (by hand using a photo editing tool). -- 100.0.73.17 (talk) 11:44, 10 December 2012 (UTC)

See earlier discussion of this below. Some SEM pictures do come coloured for very good reasons, and the colouring is not done by hand but by the instrument. Such pictures can be acceptable for publication if the protocol and justification are both clear.Plantsurfer (talk) 12:14, 10 December 2012 (UTC)
Thanks. I've added a first section on the use of color in SEM pictures; it needs work, but the issue clearly needs to be addressed. I'll add some citations next. -- Dan Griscom (talk) 13:52, 10 December 2012 (UTC)
3/4 of the references provided on color refer to internet blogs and listservers which are not reliable external sources, i.e. not acceptable per wiki policy. They should be deleted. The first reference from a refereed journal is fine. Two such additional references have already been suggested in the continued discussion "To Plantsurfer about colored pictures" below.--Esem0 (talk) 01:31, 12 December 2012 (UTC)
Thanks for catching that. -- Dan Griscom (talk) 02:19, 12 December 2012 (UTC)
And thanks to whomever added more information on the use of color to display information captured by the SEM, rather than Photoshopped in by the researcher or press agent. I do believe, however, that many or even most of the color images the public sees are hand-edited. I'd love to see more information on this, as it would be important information for a visitor. -- Dan Griscom (talk) 02:19, 12 December 2012 (UTC)

To: Materialscientist and Mike Rosoft. Let's do not stick to the previous century tradition[edit]

1. 300 V - 1kV is a new "normal" voltage for SEM. Low voltage and in-lens SEM is a way to go now. 10 kV is a way to hight voltage even for traditional SEM. Too strong edge effect and too high volume of signal generation. I myself do not go above 5 kV for most applications.

2. For at least 15 years there were no new SEMs with CRT. We cannot stick to explanations of image formation with CRT scopes any more. Time to move forward.

So, your "undo" of my editing looks too outdated.

I am waiting for your reply; otherwise I will reverse it back. Thanks, Chivesud (talk) 15:30, 17 February 2012 (UTC)


Reverted to my version. Chivesud (talk) 20:00, 22 February 2012 (UTC)

Chivesud, sorry for delay - hectic days. I agree that image formation with CRT scopes is not relevant anymore, but I do disagree with the high voltage comment - this all depend on the user, and for inorganic samples, higher voltage usually offers better resolution (charging effects aside), thus most non-biologists by default go to nearly the highest microscope voltage (say 20 keV) - just my observation. Materialscientist (talk) 00:44, 23 February 2012 (UTC)

Materialscientist, I am sorry for even greater delay.

Unfortunately, you are very wrong in your habit to “go to nearly the highest microscope voltage” for better resolution. First, usually very few micrographs are made at or close to resolution limit. Second, high voltage will make you lose fine details at intermediate magnifications. For example, river patterns on grains of fragile fracture of steel will greatly decrease in contrast at unnecessary elevated voltages. Current trend is to use as low voltage as possible for any kind of specimens. On a Microscopy listserver (of American Microscopy Society) you can find hard core fanatics of low voltage observations. I myself believe that voltage should depend on task, not on some dogma. For example, for my latest paper I used 5 kV voltages for coated specimens, 1 kV for not coated, 5-25 kV for BSE images, 2 kV for X-ray analysis (elements of interest C and O). Only very old or very misaligned microscopes demand high voltages for any work. Chivesud (talk) 14:00, 18 March 2012 (UTC)

As an experienced user of SEMs since shortly after the first one was installed in Scotland in the late 1960s I agree with Chivesud on this. A 30kV beam stimulates signal generation from depths within the specimen several hundred times greater than the resolution of a modern FESEM, swamping the signal from fine surface detail and it follows from this that the use of high kV is almost always counterproductive if the aim is maximum resolution. Only if the aim is to stimulate x-ray emission or to detect dense objects such as colloidal gold labels beneath the surface of a specimen using the Backscattered electron signals is high kV necessary. It is probably because non-biologists make greater use of analytical modes that they regard high kV as the default. It is irksome to have to switch back and forth between high-res and analytical settings, so the default will be the setting that gets most use. For highest resolution any specimen will have an optimum accelerating voltage in the range 2-5 kV where the best combination of signal to noise and resolution can be obtained. In addition, very short working distances are required for maximum resolution, and most microscopes cannot focus a high kV beam at shortest working distances because the objective lens power required is excessively high.Plantsurfer (talk) 17:49, 18 March 2012 (UTC)

To Plantsurfer about colored pictures[edit]

Hi Plantsurfer,

Colored pictures ARE NOT SUITED FOR SCIENTIFIC PUBLICATIONS. Period. Please, do not revert again my editing on the colored pictures. Thank you,

Chivesud (talk) 01:58, 24 March 2012 (UTC)

Please provide reliable sources for this strong statement. Materialscientist (talk) 02:15, 24 March 2012 (UTC)

http://www.nature.com/nature/journal/v434/n7036/full/434952a.html "Changes to selected parts of an image, such as brightening one cell in an entire field or scrubbing out an ugly blemish, are prohibited." - This citation can be applied to pseudo coloring.

Chivesud (talk) 18:33, 3 April 2012 (UTC)



Hi Chivesud, I do not disagree with you that the majority of coloured SEM images are false-coloured and that the colouring is purely arbitrary embellishment and is usually without scientific justification. Nevertheless there are valid uses for such images even in scientific publications. One such example of the publication of false-coloured SEM images appears in the following paper in The Plant Cell: http://www.plantcell.org/content/23/4/1337.full.pdf+html?sid=82d6ac36-70f6-4624-b224-ef1cd9a7b25c. page 1339 Other legitimate uses are in the publication of 1) anaglyph stereo images 2) mapping of x-ray data onto an image or 3) in other situations where multi-channel information is being presented, such as a BSE or cathodoluminescence image, superimposed on a topgraphical secondary electron image. Modern SEMs such as the Hitachi 4700 and 4800 have the capability to combine signal channels into a colour image for just this purpose. Let me know if you have any trouble seeing the pdf - if so I could send it to you by email. Plantsurfer (talk) 16:24, 24 March 2012 (UTC)

See also http://www.nature.com/nphys/journal/v6/n11/fig_tab/nphys1767_F3.html from Nature Physics 6, 879-882 (2010) and Yamada, M, Suzuki, T., Oho E. and Matsushima, H. (1998) Colour scanning electron microscopy of peltate glandular trichomes of fresh developing hops (Humulus lupulus L.). Journal of Electron Microscopy 47 (5) 539-542. An example of a colour anaglyph occurs in I. Tatar et al. (2004) Circumventricular organs of rats . . . an anaglyphic SEM study. Neuroanatomy 3, 35-37. Applied Surface Science 57, (12), 1 April 2011, Pages 5208–5212 contains an example of an SEM image overlaid with colours to show the distribution of EDX signals from three different elements. This kind of presentation is common. Another relevant link: http://www.ncbi.nlm.nih.gov/pubmed/20638857 Plantsurfer (talk) 20:21, 24 March 2012 (UTC)


Hi Plantsurfer, I agree that paper from The Plant Cell has useful utilization of coloring: it helps to calculate area and perimeter of cells (I have one paper published with similar coloring). Nature rather disappointed me: no justification for coloring image. Yamada did not used pseudo colors, he just combined optical and SEM images. Anaglyphs are still monochrome images – one red and one cyan. And we do not discuss X-ray data presentation. The last paper, from Micron, is rather childish; it is the Micron way to publish such a nonsense. By the way, I like coloring SEM pictures… So, colored images can look nice, but they should be avoided in publications.

Chivesud (talk) 19:03, 3 April 2012 (UTC)

It is all gets a bit complicated these days, because so many imaging techniques (such as confocal microscopy) combine separate data channels into one image, and not only are the gain or contrast likely to be different in each channel, but the colours assigned to each may well be arbitrarily chosen. This can apply to astronomical images too - if you look at Astronomy Picture of the Day you will find innumerable examples where x-ray or radio images are merged with visible-light images. Nature (the journal) is obvioiusly concerned to prohibit arbitrary falsification of images by editing with e.g. Pxxxxxxop, and the spirit of the thing is to preserve information integrity. However, the question of whether a photograph truly represents reality has always been an issue in scientific photography. The first departure occurred when the choice of emulsion was made (contrasty and slow or fast and soft), the second when the emulsion was developed - any manner of response curve could be cooked up by suitable choice of developer chemistry, time and temperature and the third departure occurred when the negative was printed - hard or soft paper - the choice was not usually the scientist's but the departmental photographer's. People fiddle with images using e.g. clone tools in Photoshop and think they are doing something novel, but that is far from the case. The manipulation that a professional photographer could get up to in the darkroom was capable of doing that 100 years ago, and you don't need to look too deeply into Photoshop to see that its tools are derived from darkroom tricks, implemented in digital form. Consider unsharp mask sharpening, for example. Plantsurfer (talk) 20:02, 3 April 2012 (UTC)
In further support to Plantsurfer, may I add that color is extremely useful in superimposing two or three different information signals like here, here and here. No computer processing was involved but plain superimposition of successive images carrying SE and BSE information, i.e. meaningful topographic, material/composition information (see also: Danilatos, G.D. (1986b) Colour micrographs for backscattered electron signals in the SEM . Scanning 8:9-18. Or Danilatos, G.D. (1986c) Environmental scanning electron microscopy in colour. J. Microsc. 142:317-325). Displaying all this information simulataneously in B&W would be utterly confusing.--Esem0 (talk) 03:17, 28 October 2012 (UTC)

ESEM section duplication[edit]

If a knowledgeable person could consolidate the two duplicate ESEM sections, it would be great — Preceding unsigned comment added by 99.162.70.214 (talk) 16:39, 8 April 2012 (UTC)

This section is a part of specimen preparation section. I have rewrote it to reflect the fact.

Chivesud (talk) 14:59, 27 April 2012 (UTC)

Manfred von Ardenne[edit]

I think the few words spared for Manfred von Ardenne do not make justice for the father of scanning electron microscope. Specifically, the phrase "but never made a practical instrument" portrays a denial for his great achievements. He actually constructed a prototype SEM and produced the first ever scanning electron micrographs as reported in the second part of his "Elektronen-Rastermikroskop". He was not a manufacturer to develop and produce a machine for the general public. This does not deserve him any negativity after the world has enjoyed the outcomes of his innovation for so many decades. We are not qualified judges to state that "he never made a practical instrument" except to state the opposite. He was actually both a great experimentalist and builder of electron microscopes, and a great theoretician. He is the equal to Ruska but not easily recognized as such.--Esem0 (talk) 13:33, 9 August 2012 (UTC)

Better historical account for SEM is now provided. --Esem0 (talk) 04:04, 26 October 2012 (UTC)
Are there any surviving images taken by the instruments developed by the SEM pioneers Max Knoll and Manfred von Ardenne? If so, can they be added to the article? It would also be of interest to have examples of early images produced by the Cambridge group.Plantsurfer (talk) 08:29, 26 October 2012 (UTC)
There are in the relevant references but one has to obtain good digital copies of them from the original journals and (worse) has to upload them with relevant permissions for wiki use.--Esem0 (talk) 10:15, 26 October 2012 (UTC)

Color SEM image[edit]

Does anyone have or know of a bona fide multichannel color SEM image that can be used in the article without copyright problems. Plantsurfer (talk) 12:23, 13 December 2012 (UTC)

You can find lots of images with explanation in multichannel SEM imaging and until such images might be released for wikipedia use. --Esem0 (talk) 06:00, 14 December 2012 (UTC)