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my nootloss
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[*] posted on 8-6-2005 at 12:17
spectroscope


Hey guys, I think it would be helpful for us to find a way to make a spectroscope, so we could find out what stuff is in the chemicals we buy (example, in drain cleaner, we could boil all the h2so4 and h2o off and use the spectroscope to find out what left in it…)

I was thinking of using a blank CD as the prism?
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[*] posted on 28-6-2005 at 18:11


hehe, you must be kidding, right?



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12AX7
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[*] posted on 28-6-2005 at 18:46


I've always wanted to make a mass spectrometer, but ya know, I haven't the slightest idea how the hell you ionize a solid substance. Shoot a thick e-beam at it and sputter??

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neutrino
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[*] posted on 28-6-2005 at 19:20


I think he meant to put things in a flame and watch spectral lines. Clever, although somewhat out of the scope of amateur science.
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12AX7
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[*] posted on 28-6-2005 at 21:38


Howso? A prism and scale (or better yet, color photographic film) aren't very diffcult at all.

Tim




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my nootloss
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[*] posted on 28-6-2005 at 22:32


Yeah that’s the amazing thing about it, it’s very EZ and a very good thing to have in the lab, the reason I say this is just think about all the crappie chemicals we are some times forced in to using i.e. sulfuric acid. The drain cleaner I got had some very weird things in it, so what I could do is boil it don’t and use the spectroscope to find out what I have left (sorry I used the same example 2 times, I forgot.) I am sure any one of you guys has some chemical in your lab that you would love to find out what is in it. I really don’t know a whole lot about spectroscopes, I have looked some up “spectroscope” in my books (old books, most use a prisms or so it says in the book. So I guess that would be fine).

Neutrino- I don’t really so how this is out of the range of any person who is unwavering in there quest for chemical understanding. Thank you by the way; in my book “Clever” is one of the most highly recognized words.

12AX7- please accept my apogee for my lack of knowledge, but what is a “color photographic film” and how accurate and how many times can you use one/it? All so how would we get are hands on these?

To all - I am really open to any and all suggestions on how to make one of these great things
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12AX7
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[*] posted on 29-6-2005 at 00:12


You could use B&W film too, but it'd be more interesting with color. ;)

Just a strip of photographic film covering the viewing screen, you project the spectral lines on it exposing those areas, which are then developed at the 1 hour photo into visible color. Well, if they do large strips.

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my nootloss
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[*] posted on 29-6-2005 at 06:40


i work at one so i will ask
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[*] posted on 29-6-2005 at 13:58


I once made simple CD spectroscope. It is very easy - just piece of CD disk and some lightproof box with two holes. I did this just for fun so i did not bother do draw scale. I used gas flame and sometimes voltaic arc as light source. Some spectral lines are clearly visible but there is still lot problems to solve.

There is lot of chemical elements everywhere and its not at all easy to guess which combinations can make that particular pattern. Especially if you have no proper scale. Another problem is that some common chemical elements have no intense spectral lines in visible region. For proper determination of those one needs infrared or UV spectroscopy.

I probably will continue with these experiments as its indeed usefull to have spectroscope.
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12AX7
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[*] posted on 29-6-2005 at 15:37


Dunno about IR (maybe one of those IR test cards from RadioShack, for testing your remote?), but UV you could add a fluorescent screen to the scale. :)

The only problem with diffraction gratings is the same wavelength is reflected at a number of angles, so it repeats every number of degrees. At least as I recall. So you see red orange yellow green cyan blue purple red orange...

Sodium in a gas flame would certainly give you a bright reference. I'd like to see someone clearly photograph the doublet bands on their homemade apparatus. :)

Tim




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jimwig
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[*] posted on 29-6-2005 at 17:34


go to journal of chemical education site

do title search on spectroscope

there are several for the building in the lab - if memory serves

also more amateur constructed scope are to be found in the amateur scientist column in scientific american

there is an online index for that also

google at close range

jim wiggins
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[*] posted on 30-6-2005 at 12:30


Journal of chem education is quite usefull reading. I did not know it before. Thanks jim!
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[*] posted on 30-6-2005 at 20:51


If you remove the IR filter in the lens then most webcams will detect infra-red down to 1000nm. So thats one way to view at least part of the IR spectrum.

The image intensifiers in night vision scopes also work well into the IR, though I'm not sure how far the response extends.
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[*] posted on 1-7-2005 at 12:59


You can take a screenshot from a webcam and save the picture in a standard size, bmp 16 colors. With a visual basic program it shouldnt be too hard to find out how much % of each of the basic colors you have in the pictures.
If looking at a printed picture someone is able to determine what element that is, I am sure that it can be done with a simple program on a pc.
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[*] posted on 4-7-2005 at 13:27


The typical sensors in webcams only work in the near IR about 900nm. The spectra that get used for identification by IR cover the region around 10000 nm.
Measuring UV might be easier but most condensed phase UV spectra are pretty dull, a splodge at the high energy end.

"If looking at a printed picture someone is able to determine what element that is, I am sure that it can be done with a simple program on a pc."
Interesting idea, picture recognition, like voice recognition, is actually quite difficult for a computer. If you find a simple program to do it I sugest that you sell it to the millitary for lots of $$$. The odd thing is that people are very good at it.

Anyway, there are spectrum matching programs available, the tricky bit is getting the data into the PC.
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[*] posted on 4-7-2005 at 14:55


The pyroelectric sensors used in motion detectors cover the 5-14um IR range. I guess some kind of scanning aperture would be needed to pick out individual IR lines.

That still leaves a hole from 1um to 5um - maybe the old military image intensifiers could be used ? I've got one that uses IR down to 3um IIRC.

[Edited on 4-7-2005 by Twospoons]
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[*] posted on 5-7-2005 at 08:57


Or you could cover a coil of fine wire with soot from a candle flame.
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jimwig
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[*] posted on 5-7-2005 at 11:49


would you be so kind as to elaborate

aka duh!!!

on the soot idea.

thanks
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[*] posted on 9-7-2005 at 02:56


I seem to be talking bolometers.:D
that should be enough for you to google.
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[*] posted on 9-7-2005 at 21:04


Um... I have to make a quick guess about what such a thing is, before googling. Is it a coil of light-absorbing wire that changes resistance with temperature, therefore acting as a primitive light meter? I will edit to say, I was wrong, when I find what it is.

edit: crazy - I guess I was somewhat right. However, they are not primative at all - cept in the variety we might make, of course - some are used in submillimeter astronomy and involve cooling to millikelvins.

edit2: to add a question, what kind of light sensor is used in a IR spectroscope unit?



[Edited on 10-7-2005 by Oxydro]

[Edited on 10-7-2005 by Oxydro]




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[*] posted on 10-7-2005 at 07:07


This might help
http://hiq.linde-gas.com/international/web/lg/spg/likelgspg....
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[*] posted on 16-7-2005 at 22:47


Voice recognition is quite a bit more complicated than reading a bitmap and count how many pixels of each color you have. And we are not talking about a complex image. Just a 16 or 256 colors bitmap with a 'rainbow' in it.

[Edited on 17-7-2005 by Archimede]

[Edited on 17-7-2005 by Archimede]
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[*] posted on 17-7-2005 at 00:38
LED's as a light sorce for a Spectrophotometer


Posted on 12-7-2005 by Lambda:
"The narrow bandwidth of LED's"
https://sciencemadness.org/talk/viewthread.php?tid=4114&...

Addition:

In the UV-spectrum quarz cuvets will be required due to the high absorbtion of normall glass.

In the visible spectrum glass cuvets may be used.

In the IR-spectrum kitchen salt (NaCl) works out just fine. You will have to press the mixed sample into tablets, or.....good luck !
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[*] posted on 17-7-2005 at 12:54


Oh, I am so confused.:(
From what I understand from this thread, we can/want to(?) create a primitive IR spectrophotometer, which could be made up of:
an IR detector(bolometer or what not)
a prism/diffraction grating (a cd/dvd)
a sample holder made of NaCl for the plates
and some monochromatic IR LEDs for the light?

What confuses me is why use a picture and software to determine the number of colours. Aren't we after the IR portion of the spectrum spread? How do you take a rgb picture of that?

Anyways,
My org-chem textbook's IR spectrum graphs go from 2.5 to 15 microns. I suppose thats the range we could be aiming for. Is there any other info to verify this?

and also pyroelectric detectors(from IR motion detectors) only have such a narrow range of detection because of a filter window. Maybe if we could remove the window or replace it, we could use it for all the other wavelengths?
Info taken from here
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12AX7
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[*] posted on 17-7-2005 at 13:09


AFAIK, you don't have to (and can't! :D )worry about "color" (i.e., wavelength expressed as an appearance, which loses meaning outside of the narrow visible spectrum of course!), so you use the spectrometer which alters wavelength to position on a scale. Then you just read off position of the intensity bands. So yeah, you'd probably get IR and UV as a monochrome scale photograph, unless you want to use a more sophisticated spectrum such as intensity varying color (heat-sensitive video and radar images for instance use this), or try to transpose visual colors down a few orders of magnitude - of course, this needs a camera that senses IR bands individually.

Tim

[Edited on 7-17-2005 by 12AX7]




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