For IR or RAMAN spectrum
interpretation or Validation of spectrum and molecule some parameters
might be set to take influence on analysis results. However, in most cases
automatic selection of parameters will provide good results, because the
automatic parameter detection will analyze each spectrum and adjust settings
especially for the current spectrum. Of course all parameters can also
be adjusted manually.
Parameters are stored in the Interpretation
Any parameters adjusted in this dialog will be stored
together with the interpretation rules in the database. Thus modification
of those parameters will modify the rule database. You will be prompted
to save or discard changes, if you leave the application or switch to
another rule database.
This also means, you may have different parameters
for IR and RAMAN interpretation depending on the actual analysis
For spectrum interpretation peaks need to be identified in advance.
The parameters in this section are identical to those of the Find
Peaks function in the "Mathematics"
section of the software. Only identified peaks will be considered in the
If the automatic peak detection is enabled, various algorithms will
find a suitable set of peaks for spectrum interpretation. Otherwise you
may adjust the parameters below for peak detection.
If enabled, the baseline of the spectrum is automatically corrected
to obtain more precise peak detection results. No particular parameters
can be set here.
This parameter controls the minimum absolute or relative peak height.
Only signals with intensities beyond this value will be identified as
Use Absolute Peak Height
This parameter controls the peak height detection mechanism, which
is one of the following:
Absolute Peak Height (checked)
The absolute peak height is determined from zero to the maximum
Relative Peak Height (unchecked)
The relative peak height is determined from the imaginary baseline
of the peak to the maximum peak intensity.
This parameter controls the minimum peak width. Only signals with at
least this minimum peak width denoted in wavenumber units will be identified.
An existing peak table overrides
peak detection ...
If you are not satisfied with results derived
from automatic peak detection or peak detection with height and width
parameter, you can provide your own list of peaks for analysis. In this
case, please find peaks yourself using the "Find Peaks" function
from mathematics section before starting IR/Raman Interpretation.
An existing peak table overrides peak detection
of the interpretation algorithm. In this case the existing peak table
is considered for analysis.
Band Detection Tolerance
Interpretation rules represent the expected positions of bands in a
spectrum. However because of physical or solvent effects sometimes bands
are shifted and will not appear at original position. This might cause
incorrect identification in some cases. If signal shifting is observed
in the spectrum, you can correct for it by setting a particular deviation
in wavenumber units. Bands will then be identified in their original expected
range and also in an interval around.
This parameter controls the size of the tolerance interval for each
IR or RAMAN band.
The strength of a signal in the spectrum strongly depends
on chemical environment and physical properties of the substance. In interpretation
rules, expected signal strengths are stored being compared now to the
current sample spectrum signal intensities. With intensity threshold settings
below the analyst encodes the strength of signals in the analyzed spectrum
from his personal feeling using the following categories:
The numbers behind these qualitative intensity categories
represent the expected intensity ranges in absorbance units where very
weak, weak, medium, strong and very strong signals are expected. Peaks
appearing within one of the categories will be identified accordingly.
Intensity values of these categories span from 0 to 1.5 absorbance units.
Categories are allowed to overlap.
Normalization of the spectrum.
The intensity of the highest
detected signal in the measured spectrum is automatically scaled to 1.5
absorbance units. The lowest intensity (usually the base line) in the
spectrum is set to 0. All intensities in between will be scaled accordingly.
This procedure is called normalization.
By default and as long as the Automatic checkbox is enabled, these intensity
categories will be determined automatically by some algorithms in the