FTIR Spectra
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Author:  G4Lab [ Sat May 08, 2010 11:00 pm ]
Post subject:  FTIR Spectra

Where I "work" ( :smt044 ) we got a big NSF grant to buy an FTIR microscope and a confocal Raman microscope. Since these instruments are way into six figures the people selling them are happy to bring them for you to play with. Hoping you will buy theirs. Round one was This one

One of the first spectra we took was Barium Sulfate White. It is one of the materials used for integrating spheres and is not only white in the visible but pretty far into the infra red. The graph shows it is pretty non absorbing until you get into the about 8 micron range (8,000 nanometers) These measurements are done in wave numbers, which take most people a while to get used to.


The principal investigators on this project are of the female persuasion.
When I pulled out a diamond color master set to try out the Diffuse Reflectance Sampling accessory it created quite a sensation.


Notice that the morphology of the spectra are all identical except for the H-I colored stone. It must be a different type of diamond. The IR absorbance tracks the visible absorbance even though it would not have any effect on the perceived color of the stone. Most of that occurs in the 415 nanometer visible range.

Below are the spectra of the color set stacked on one another. In the longer end of the spectrum (fewer waves per cm because wavelength is longer) the absorbance tracks the visible (yellow) color pretty well. But if you look closely you can see that the curves criss cross a bit in the shorter wavelength area.

They also brought one of these which only costs about $20,000 with a sampling accessory and software. They say they have had good luck selling them to some big jeweler's and diamond dealers.

Author:  Alberto [ Mon May 10, 2010 5:56 am ]
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the H-I curve is weird, it seems it has a N peek too.... :roll:

Author:  G4Lab [ Mon May 10, 2010 9:37 am ]
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We ran it twice and got an identical curve both times.
I have not had time to look up what the significance of the difference is, but I expect to discover that different types of diamonds have different IR spectra.

If any list members can shed light (no pun intended :lol:) on the subject
I would be pleased to hear what they have to say.

I am going to try to take a Raman spectrum on that diamond and at least one of the others, to see if there are differences there.

Author:  Olivier [ Mon May 10, 2010 11:55 am ]
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Arfff would love to have such tools to play around!
Thank you Gene for sharing!

Author:  Tim [ Mon May 10, 2010 6:13 pm ]
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Well Massa, you certainly found your spot there... super!

Author:  Brian [ Tue May 11, 2010 2:10 pm ]
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Wow, a FTIR microscope AND a Raman microscope! All we got for xmas was a SEM, and both the EDS and EBSD will have to wait another day. So no cool new spectra collecting for me. :smt022

Author:  G4Lab [ Tue May 11, 2010 8:19 pm ]
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A Zeiss. That's pretty cool. LaB6
We have an SEM. From the early eighties. No X ray either.

But it helped me get the job. I had previously owned TWO of them.
Someone had swiped the EDX detector but I did have the Kevex software and a PDP8 and hardware. I found two EBSDs on ebay. Where I also found one of the scopes.

When I was admitted to anesthesia school I serendipitously ran across someone who wanted to buy them so I sold them.
Even though the unit is pushing thirty and ocassionally presents me with a geriatric problem, it still takes a terrific picture.

And the gal who runs it bought a software and hardware package that I was looking at,, which eliminates the polaroid film and makes digital images.

I thought I was going to get to play on it more but even though she lets me fix it , she is so possessive of it, that I haven't even asked. (She is EXACTLY the way I would be, if it were mine)

Unfortunately it has developed a seeping oil leak in the high voltage cap. So I think it may get retired soon. She has been campaigning for a newer (not new ) one.

Author:  Brian [ Tue May 11, 2010 10:52 pm ]
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G4Lab wrote:
A Zeiss. That's pretty cool. LaB6

Yes, but I will be campaigning for an EDX. Pretty pictures are nice, but elemental analysis of what you see is even better! Just like... looking through a microscope is nice, but chemical analysis of what you are looking at is even better!

Anyways, amazing how automated and non-user-serviceable it is.

Author:  G4Lab [ Wed May 12, 2010 12:46 am ]
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Yesterday the Renishaw guy put one of our samples (not mine) under the Raman scope and did a bunch of keystrokes. The specimen was a silicon chip with some aluminum contact lands. He picked out characteristic bands for each element and then made an elemental map. But since the scope is confocal he could do depth mapping. In a very few minutes he had this 3D image which he was whirling and twirling on the screen.

The companies can't make any money if you service it yourself. And as I always tell the profs I work for I would prefer some clunky old piece of junk from when the university was built (science building about 1970) to a new thing with a microprocessor that isn't made anymore and PROM code that no one in the company has looked at since the guy that wrote it got laid off twenny years ago.

But in fairness that automation can do alot of tricks including tracking the health of the goodie.

Author:  James Baer [ Wed Jul 14, 2010 10:52 am ]
Post subject:  Re: FTIR Spectra


Looking at the H-I spectra I noticed that most of the bands/peaks
of the other stones are present but greatly diminished in magnitude relative to the baseline. You also have a higher baseline absorbance across the full spectrum.

I suspect alot of the light escaped the stone for some reason which would account for both the higher across the spectrum absorbance and diminished absorbance by the bulk material. Why this occured would need to be looked into. If it was a positioning issue I would have expected the stone to give a different result on the second test (unless the stone was in exactly the same position for the second test).


Author:  Bear Williams- SGL [ Sat Sep 04, 2010 10:48 am ]
Post subject:  Re: FTIR Spectra


Looks like all the diamonds on your FTIR are TypeI with the exception of your H-I color which is lacking the H peaks. It is most likely of the TypeII variety.

If you test on the Raman they should all show only a single C-C bond at 1332cm-1, if there is a possible HPHT treatment on the H-I stone, you may detect lattice distortion and get a 1333 line... it's very subtle.


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