I am analysing solid and powder samples using the ATR mode for FTIR spectroscopy. When I am taking the background scan, does it make any difference whether I clamped down the pressure device onto the crystal? Also, would that affect the accuracy of the results of my spectra obtained?
Clamping down the pressure device onto the pure crystal will give its spectrum and may give you signals of any impurities adhering to it. You can check that by recording a background with no clamped down pressure device and record a spectrum of the clamped down pressure device.
Anyway, pressure devices are used to increse the contact surface with the analyte, so there is no reason to clamp it down for background recording.
Be carefull and read the instrument manual, for diamond ATR it could be dangerous to clamp down pressure device directly onto the ATR crystal.
It should be more acurate to record ATR spectrum without clamping pressure device to ATR as the preassure tip might introduce same spectral features.
Hello Thomas and Justinas,
Thank you for your recommendations! Unfortunately I could not find the instrument manual at the laboratory and the online pdf version did not give much details about taking background scans.
I will take note of this and avoid clamping down the pressure device when i analyse my compounds next time.
With a diamond atr you are probably safe to clamp down but make sure that all the components (the diamond as well as the pressure device) are clean. Please note that if the diamond is not securely mounted it can shift under pressure, which means that the background spectrum can change as a function of pressure. I’ve seen this happen a lot using Germanium atr elements that are glued into the holder with epoxy. The epoxy can soften over time, particularly when cleaning with aggressive solvents, and moves a little under pressure. If the backround scan isn’t recorded using the same pressure as the sample scan then you can get weak epoxy bands in the sample spectrum. If your accessory has the diamond glued in place this could be a problem
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