Cary 630 FTIR Spectrometer Performance fail

Hi itnick,

which accessory / sample module are you using? Depending on the accy (ATR, Transmission, etc.), the value is low (or very low) for S-N. Do you have a KBr engine (blue-ish window) and is it foggy/contaminated with scratches/fingerprints/moisture/droplets, etc? In that case the window, or the detector might need replacement as the result is quite low for SN.

Regarding the laser frequency: uncheck the "Check value only" checkbox and retry the Laser Freq test with polystyrene. Now, when the "calculated laser temp. intercept" (RHS bottom of the screenshot you sent) has a new value, click the "Set" button on the right to accept the new value. This recalibrated the laser freq. If you now perform the test again, it should pass.

Hi, Thanks for the reply, i using only Diamond ATR.I will check tomorrow the window-kbr engine.  For laser freq test i tried recalibration more 5x times, but no good results. The results always differ.

In my opinion, the window looks in good conditions.

Hi itnick, sample window indeed looks okay from what I can see in this picture. Usually, best way to check any contamination is to look at it from <30 deg angle; the glance/reflection of the room light will show any deposits on the window.
That said, it could be the KBr windows inside the engine (i.e. beam splitter) could be damaged if it keeps failing SN test - you cannot see this from the outside and this will require a bench repair in one of the Agilent repair centers. I'd recommend to contact your local CustomCare team and they can handle from there. 

It can fail the last peak (around 3000 cm-1) because contact with the ATR anvil is not sufficient. The IR through the diamond only has a limited range (I believe it's <25 um), therefore the sample needs to be in direct contact with the diamond. You can do this by adding several "ATR spacers" on top of the polystyrene film, or just simply get a plastic bag / piece of paper / elastic band and place this on top of the polystyrene film and below the anvil. This will increase the signal significantly. Watch the live signal (right before starting the calibration) and make sure the big peak at ~1000 cm-1 has a minimum Abs of approx. 0.9, but often you can get to 1.0-1.2. This means the actual problem (peaks at ~3000 cm-1) have enough signal to get through the laser calibration.

Good luck!

Hi,Thanks for the answer, I will try.