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

Note
If you have turned off Prompt To Insert Or Remove Sample and are collecting a
background before every sample, you will be prompted to install the sample after
background collection. Similarly, if you are collecting a background after every
sample, you will be prompted to clear the beam path after sample collection. ▲
Displaying a warning if
the aperture is too large
Warn If Aperture Too Large To Attain Resolution lets you specify whether the
software will warn you if the aperture size is too large to achieve the specified
resolution. (Increasing the aperture size reduces the resolution.) If the warning
appears during data collection, use a smaller aperture or a lower resolution (higher
setting of the Resolution parameter). See “Setting the aperture size” and
“Specifying the resolution” in the “Collect” chapter for more information.
Normalizing the
frequency automatically
Normalize Frequency lets you specify whether the laser frequency of spectra you
collect is automatically normalized. Normalizing the frequency changes the
locations of the spectral data points to standard positions; that is, the positions they
would be at if they had been collected using a spectrometer with a reference laser
frequency of 15,798.0 wavenumbers. This results in better correspondence of data
collected using spectrometers with slightly different laser frequencies.
Normalize the spectra of your standards and unknown samples if you are developing
or using a quant method on more than one spectrometer. You should also normalize
noncalibrated spectra; that is, JCAMP-DX spectra, spectra from CSV (commaseparated
values) text files, and spectra collected using dispersive instruments.
The frequency is normalized only if it is not equal to the reference frequency and
the difference between the two is less than 20 wavenumbers.
Important
Note
Normalizing the frequency guarantees that data points occur at the same frequency
positions. This lets you move data between spectrometers without the problems
associated with inconsistent data point positioning. However, if you plan to analyze
sample spectra using previously calibrated quant methods developed with a version
of OMNIC earlier than 3.0, do not normalize the frequency of the sample spectra. If
you normalize your sample spectra and attempt to use a calibrated method whose
standards were not normalized, the data will not match and the analysis will fail. ▲
You can use Normalize Frequency in the File options to specify whether to
normalize the frequency automatically when you open a spectrum. See “File
options” for details. Use Normalize Frequency in the Process menu to normalize the
laser frequency of a spectrum already displayed in a spectral window. See
“Normalizing the frequency of a spectrum” in the “Process” chapter for details. ▲
When you normalize the frequency of a spectrum, a record of the operation is
made in the “DATA PROCESSING HISTORY" section of the Collection And
Processing Information window.
88 Thermo Nicolet