Subtracting One Spectrum from Another in KnowItAll



How do I use KnowItAll to subtract one spectrum from another?



For spectral subtraction, use the ProcessIt IR application in the spectral processing tool box along the left hand side of KnowItAll.

  1. Open your mixture spectrum in ProcessIt IR.
  2. Use File > Open Overlay Spectrum to open the spectrum that you would like to subtract.  (NOTE:  You can also copy a spectrum from another KnowItAll application and Paste it into ProcessIt IR. Select the spectrum that you would like to subtract. The choose Edit > Copy. Go to ProcessIt IR where you have previously opened the mixture spectrum and select Edit > Paste.)
  3. Select the Process menu in ProcessIt and click Add/Subtract Spectrum. Your Experimental Spectrum will be the sample. The Reference Spectrum will be the component you would like to subtract. The factor may have to be adjusted depending on what you see in the preview. Click the preview button to view the effects of your adjustments.
  4. When you have finished making adjustments, click Replace to finish the subtraction.