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Problem
Possible Cause
Solution
A spectrum is too noisy.
There were too few scans.
The resolution was too high.
The purge gas flow rate or
pressure is too high.
The detector is saturated.
The moving mirror velocity is
set too high for the detector.
The sample in an ATR
experiment is not in good
contact with the ATR crystal.
Increase the number of scans on the
Collect tab of the Experiment Setup
dialog box.
Reduce the resolution (use a higher
numerical setting) on the Collect tab
of the Experiment Setup dialog box.
Check the pressure regulator; it should
be set between 0.7 and 1.4 bar (70 and
140 kPa, or 10 and 20 psig). Check the
flowmeter; it should read 15 scfh
(about 0.4 m
3
/hr). Adjust the flow rate
if necessary.
Add a bandwidth-limiting filter or an
energy screen to reduce the signal
strength.
Set Velocity on the Bench tab of the
Experiment Setup dialog box to a
lower value.
Reapply the sample to obtain more
consistent contact between the sample
and the ATR crystal.
154 Thermo Electron Corporation