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Author: Subject: Buying an IR spectrometer
Siddy
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[*] posted on 4-11-2008 at 19:50
Buying an IR spectrometer


Im interested in buying an infrared spectrometer (a decent FT-IR one) and want to know about what sort of maintenance they need. Ive looked around and you can pick up a circa 1995 used model for under 2k (USD) and i think thats pretty reasonable since i would use it more than my 4k tv.

The 2nd hand units for sale are always the sold with no software or manual, so i know i would have to source the software and possibly drivers for my computer.

Ive used them a lot but i dont do the maintenance, the systems are always ready to go when i get there. But i have read that the detector needs filling with liquid nitrogen. Can anyone tell me if this is true, and how often the nitrogen needs to be replaced. Also are there any other consumable type maintenance that they need? (im talking about basic FT-IR's, nothing fancy, no MS attachments etc...)
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DrP
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[*] posted on 5-11-2008 at 01:27


There are companies that specalise in IR maintenance. What country are you in? We had a maintenance contract (about 2 or 3 hundered pounds a year) to cover our IR for breakdowns and yearly service. I don't think all of them need Nitrogen do they? If yours does I would think it would want refiling fairly regularly as it boils off quite quick.



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Siddy
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[*] posted on 5-11-2008 at 02:35


?
I dont have one, im asking if they need CONSUMABLE things, such as refilling with nitrogen.

Any mechanical maintenance i could do with a guide, but i want to know if they have an on going cost from CONSUMABLES.
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DrP
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[*] posted on 5-11-2008 at 03:00


Not much as far as I know. I've never known an IR to need liquid nitrogen (why?). As I said - we used to get someone out once a year for servicing - this is not that expensive. Consumables I would think would be things such as KBr disks, polishing kits, curvettes etc.. Are you in the UK? if so then I'll give you the details of that servicing company if want it.


OK - I've just looked arround and it seems that some of the new swanky detectors do use Nitrogen. They will want refilling nearly each session you use the machine.




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Siddy
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[*] posted on 5-11-2008 at 03:58


Thanks, no im not in UK.
Im happy to hear its only swanky detectors that need nitrogen!
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chief
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[*] posted on 5-11-2008 at 04:38


They make a science of the glowing-elements (light-sources), as it seems.
I have an old one in the basement (1979 model, perkin elmer), and I went to the Infrared-Prof of the University: He told me: Glowing elements have to be replaced, very expensive etc. .
I didn't believe him, anyhow, since one can use the black-body-radiation of anything at a known temperature, and re-calibrate the instrument to that (may be too complicated for a Chem-Prof, though (as long as he has enough money to destroy on replacement-parts)).

The difference of old- vs. new spectrometers (not sure about IR, but true for visible) is,
==> that the newer ones work as Michelson-interferometers,
==> which was possible due to computer-developement, from the 90's on,
==> because since then the fourier-transformation could be carried out at some speed.

Therefrom the new ones measure _much_ faster, not needing 5 hours for 1 spectrum any more.
Thats how the new ones are peferred, and the old ones are used, until some replacement gets necessary or they fail, but noone wants to keep the old ones if a new might be had.
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ordenblitz
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[*] posted on 5-11-2008 at 14:41


I bought my Nicolet 360 in 98 and since then haven't done much of anything to it except dry out the desiccant cartridge once in a while. I'm still on the one 100 gr. bottle of KBr as I tend to favor using the MIR accessory as often as possible. Very reliable and besides the initial price, it only has cost electricity to far.

I believe the only FTIR units that require LN2 to cool the detector is the IR microscopes.
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Siddy
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[*] posted on 5-11-2008 at 15:32


Thanks a lot guys!

For the nicolet, as thats probably similar to what i will get,hHow did you get the software, and does your computer need a specific driver to run the IR or only software and cables???
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ordenblitz
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[*] posted on 8-11-2008 at 10:03


I bought the unit new so all the software drivers and cables came with it. Just plugged and played!
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[*] posted on 28-11-2008 at 06:32


IR spectrometers tend to be delicate. The things that can go wrong are:

The IR source (glowing filament)
The laser usually a gas laser (expensive)
The windows they are made of "salt" and so, particularly in humid environments, can frost as can the beamsplitter (if the internal desicant is not replaced regularly).
Also I have had problems with the electronics (a nicolet).
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[*] posted on 28-11-2008 at 13:41


I have a Thermo-Nicolet 6700. Despite being relatively new, and hence, expensive, it conforms technology-wise with the older units. I do not run N2, but I have the option. It is to ensure that the salt optics are not ruined by the moisture in the air (and to avoid the CO2 "snake fangs" and other artifacts).

Because the unit runs hot, so long as it is not turned off, you should have no problem. The only "consumables" that I need are the dessicant (silica gel) dry bags which go inside the unit. Mine survived 15 days without electricity and at 100 % relative humidity after hurricane Gustav. The dry bags and indicators were still blue (the unit is well sealed). Booted right up (USB), zero was stable, and the accessories (ATR) were likewise fine.

Get a decent unit in good repair and there should be no problem. Glo-Bars are very tough and the power supply is more likely to fail then the source. The detectors (Mine is DLaTGS) are also quite tough. I will recommend, however, removing the beamsplitter (e.g. mine is KBr) and storing it in a sealed dessicator prior to an expected natural disaster. Mine is modular and can be easily removed/re-installed via aligning clips and a thumb-screw.

Cheers,

O3




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domaani
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[*] posted on 29-11-2008 at 04:33


I've been told that at least in some models it is important to have the optics compartment filled with inert gas, such as oxygen-free nitrogen. If air is present, glowing filament tends to form malicious nitrogen oxides.

I've bought a Perkin Elmer 1600 series FT-IR a year ago. It's still waiting for some service. It was sold "as is", indicating some errors after the self test routine. I bet those are all caused by a leaking memory battery which has spread it's electrolytes on the circuit board below.
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