Choose Subtract from the Process menu. The difference spectrum is
displayed full scale in the bottom pane. This spectrum is the result of
subtracting the reference spectrum from the sample spectrum using the
subtraction factor shown to the left of the result. If you are not
satisfied with the subtraction result, you can change the subtraction
factor.
?
In OMNIC Help Topics find “spectrum” in the Index and go to
“Subtracting spectra.”
What should I use subtraction for?
Subtract is commonly used to remove spectral features of solvent
residues or pure components from the spectrum of a mixture of
compounds. When you use Subtract, the software calculates data
point by data point the difference between the two.
Spectral subtraction is useful in a variety of situations, for example...
•
Eliminating solvent peaks in a spectrum of a sample that is
dissolved in a solvent.
•
Separating components from a sample that is a mixture of two or
more components.
•
Identifying an unknown contaminant by subtracting out the
known sample material.
•
Ensuring quality by subtracting an original batch sample
spectrum from a spectrum from the next batch.
Nicolet FT-IR User’s Guide 117
