How to improve the
signal-to-noise ratio
If you primarily analyze qualitative data, you may wish to optimize
the system for a better signal-to-noise ratio. This can be particularly
important when you are working with scattering samples and
samples that absorb more infrared energy. These samples produce
smaller signals that can be “lost” in the noise.
There are several ways to improve the signal-to-noise ratio. The
most commonly used method is to increase the number of scans.
This both reduces the noise level and makes small absorptions easier
to distinguish. You can also improve the ratio by reducing the
resolution (that is, using a higher Resolution setting).
Another method is to use an energy screen that transmits more light
(or no screen at all). In this case, the resulting spectrum might be
distorted and accuracy and stability could be reduced. Checking the
single-beam baseline in the region below the low-end cutoff will
give you a rough idea of how much distortion is occurring. If the
distance from the baseline to 0 is more than 15% of the spectrum’s
maximum intensity value, you may have difficulty reproducing the
results.
Note
If the distance from the baseline to 0 is greater than 20% of the
spectrum’s maximum intensity value, your detector electronics may
be overloaded. Contact technical support for assistance.
S
In Spectrometer Help Topics view “Setting up experiments” for
instructions for installing filters and energy screens.
Nicolet FT-IR User’s Guide 69
