Thermonicolet Omnic Software User's Guide 6.1 (PDF) - Charles E ...

Adding a spectrum to another spectrum
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By adding two pure component spectra together, you can produce a
theoretical composite spectrum that is the sum of the two component spectra.
This theoretical composite spectrum can be compared with an unknown
mixture spectrum in a quantitative analysis.
If you want to perform a “scaled” addition, use Multiply to multiply one or
both spectra by a number before adding them. See “Multiplying a spectrum
by a number” for details.
Add is useful for joining together two spectra of different spectral ranges.
Performing
arithmetic
operations on spectra
Use Spectral Math in the Process menu to perform arithmetic operations on one or
two selected spectra. You specify the operations to perform by typing or selecting
a sequence of mathematical symbols and numbers. The software performs the
operations on the Y values of the data points in the spectrum or spectra and then
displays the result spectrum.
When you choose the command, the Spectral Math window lets you type the
desired operations in the Operation text box. You can also select one of the
operations provided in the Operation drop-down list box.
For example, if you are subtracting a single-component reference spectrum from a
spectrum of a mixture of two components, select (or type) the operation
A - k*B
where A is the mixture spectrum, k is the subtraction factor and B is the singlecomponent
spectrum. The result of the operation is a spectrum of the other
component.
The following table explains the symbols that you can use and gives some examples.
Symbol Meaning Examples
A Spectrum A.
B
Spectrum B, if used.
+ Add. A+1
A+B
- Subtract. -A
A-1
A-B
* Multiply. A*1.25
A*B
1 added to spectrum A.
Sum of Spectrum A and Spectrum B.
Spectrum A multiplied by -1.
1 subtracted from Spectrum A.
Spectrum B subtracted from Spectrum A.
Spectrum A multiplied by 1.25.
Spectrum A multiplied by Spectrum B.
(continued on next page)
OMNIC User’s Guide 225