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Analyze spectrum

IR and RAMAN spectrum interpretation allows automatic and interactive analysis for popular IR or RAMAN bands in a single spectrum based on predefined interpretation rules. A list of identified peaks and corresponding functional groups are returned as a result of the analysis.


Before you start IR and RAMAN spectrum Interpretation...

Please make sure to load an IR/RAMAN interpretation rule database. (By default a rule database is available already)

Expert users, please configure Preferences properly, before you start analyzing spectra.

Analyzing an IR or RAMAN Spectrum

Toggle to the right analysis mode before analyzing a spectrum!

Before analyzing a spectrum, please toggle the analysis mode to the one you want. The rule database is loaded for the actual analysis mode accordingly!
To toggle the analysis mode, choose the Toggle to ... menu command in the IR/RAMAN Interpretation Menu.

To analyze a spectrum, please follow the steps below:

  1. Open an IR or RAMAN spectrum from a file or project.

  2. From the IR/RAMAN Interpretation menu, select the Analyze Spectrum command.

  3. The spectrum is analyzed automatically and results are presented in a new tab window as described below.

Presentation of Spectrum Analysis Results

The example shows the result of an IR-Spectrum interpretation. For RAMAN-spectra similar results are obtained with the same features.
After starting spectrum analysis successfully, the results will be displayed in the
Spectrum Analysis Result dialog:

The analyzed spectrum is displayed in the spectrum view on top of the dialog. For details about the spectrum view functionality, please refer to the chapter "Spectrum View Functions". Matching functional groups are listed in a  table on the bottom. It shows identified functional groups including related information from the rule database:

  • Quality Value

  • Name of the Functional Group

  • Name of the corresponding Chemical Sub Class

  • Name of the corresponding Chemical Class

For current selected functional group, the sub-set of passed interpretation rules is shown in the upper left table. Failed interpretation rules are shown in the upper right table. Each functional group possesses a corresponding molecular representation. It is shown inside the spectrum view. For details about the molecule view functions, please refer to the chapter "Molecule and Functional Group View".

Highlighting Vibrations

You may highlight corresponding spectral region of a vibration by selecting an entry in the pass or fail table.

  1. Click the Left Mouse button on an entry in the pass or fail table to select a vibration.

Selection looks like this:


The horizontal bar on top of the spectrum is an additional indicator for the spectral width of the interpretation rule.

Show Identified Peaks

IR and RAMAN interpretation strongly depends on peak detection, which is done prior to analysis. In order to see the identified peaks you may activate peak markers in the spectrum view of the spectrum analysis result. When activated, the peak position is indicated by a vertical red line.

For details please refer to the chapter "Peaks" in section "Data View Enhancements".

How do I control identified peaks?

Sometimes it might be necessary to modify peak detection parameters, because automatic peak detection does not produce satisfactory results. You have the following options to take influence on peak detection:

  • Open the Preferences dialog and change "peak detection" settings there. Please refer to the section "Preferences" for details.

  • Before you analyze a spectrum, perform manual peak detection using the Find Peaks function in the Mathematics menu of the software.
    Analysis only considers your personal set of detected peaks then.


You may also like to review all identified peaks. They can be colorized in the spectrum to reveal not yet analyzed areas. Please refer to the chapter "Highlight all assigned Functional Groups" for details.

Sorting Matching Functional Groups

You may sort matching functional groups table by a preferred column:

  • Just click with the Left mouse button onto the caption of the desired column. The table will be sorted in ascending alphabetical order.

  • A second click with the Left mouse button onto the same column caption will sort the column descending.

Modifying Interpretation Results

After automatic interpretation has been completed, results can be modified and updated manually by the user because of the following or other reasons:

  • Some of the peaks in your spectrum may not be identified by automatic spectrum interpretation.

  • Others have been identified, but from your point of view, assignment is not correct.

Deleting Functional Groups from Interpretation Results

Functional groups that have been added to the list by mistake can be removed as follows:

  1. Click the Functional Group to be deleted with the Left mouse button in the table.

  2. Press the DEL-key on your keyboard

  3. Alternatively, Select the Remove Selected Functional Group command from the IR/RAMAN Interpretation menu.

The functional group is removed without further notification.

Adding Functional Groups to Interpretation Result

You may add functional groups for a peak in your spectrum by selecting a suitable one from the rule database. The Functional Group Browser will help you to identify suitable functional groups and lets you add them to the current interpretation result. Please follow the steps below:

  1. Move the mouse pointer close to the peak of interest in the spectrum area.

  2. Click the Right mouse button inside the spectrum view to pop-up a context menu.

  3. From the context menu, select the menu entry Show all Functional Groups at...
    The Functional Group Browser opens and shows a list of best matching functional groups at the selected peak position.

How to use the Functional Group Browser?

 Please refer to the chapter "Functional Group Browser" for details on navigation inside the browser.


  1. Select a functional group from the list in the Functional Group Browser.

  2. Click the Add Functional Group to Result button to add current selected one.

  3. Move the black vertical line to other frequencies / Peaks of interest.

  4. Repeat steps 4 - 6 until all required peaks have been assigned.

  5. Click the Close button to return to your initial interpretation result.

Show Functional Group Definition

It might be important for improving the rule database to easily review a functional group definition. The actual selected functional group can be reviewed in the Rule Designer using the Alt-F12 keys shorthand or alternatively use the following menu command:

  1. Select a functional group from the list in the spectrum analysis result.

  2. From the IR/RAMAN Interpretation menu, select Show Functional Group Definition.

Both methods open the Rule Designer window to show the actual functional group. Here you may review related functional groups or modify rule definitions to optimize the rule database.

Share Results with other Applications

Contents of any table in the interpretation result can be copied to the clipboard and pasted in other applications.

Please refer to the chapter "Copy and Paste Opportunities" in the section "Using the Software" for details.

Saving Interpretation Results

Interpretation results can be saved to file or into a project to be reloaded for review later on.

To learn more about saving objects in the software, please refer to the chapter "Save" or "Save as" in the section "Commands".

To learn more about adding objects to a project, please refer to the chapter "Add all Objects in the Window to Project" in the section "Commands".

Printing Interpretation Results

Results can be printed using a predefined Interpretation Result Print Layout. Contents of the printout can be customized there.

Please refer to the chapter "Interpretation Result Print Layout" in the section "Printing" for details.