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Problem
Possible Cause
Solution
The baseline of the
spectrum is not flat.
The KBr pellet was made with
coarsely ground KBr powder,
or the KBr pellet was
improperly pressed.
The background spectrum for
a cast film was collected with
an empty sample holder in the
infrared beam.
The spectrometer is not
properly aligned, causing a
sloped baseline.
The spectrometer has not been
on long enough to reach
thermal equilibrium.
The spectrometer is not
properly purged.
Be sure to press the pellet properly.
Remove the sample holder and collect
the background again.
Use the Align button on the
Diagnostic tab of the Experiment
Setup dialog box to align the
spectrometer.
For best results allow the spectrometer
at least one hour to stabilize after
turning it on.
Check the system to make sure the
correct purge gas is being used and
that the flow rate is correct.
Nicolet FT-IR User’s Guide 153