Options of the Spectrum Window

Besides changing the appearance of the Spectrum window achieved directly by clicking on the SpWin toolbar or by keyboard functions, several other features can be changed by items of the Spectrum menu or in the Options section of the File menu (Spectrum tab).

In the Spectrum menu, there are the following functions, that are mainly used for preparing the IR spectrum for interactive work.

• Crop to Selected Area – this command should be used with caution, because it irreversibly crops the spectrum to the range displayed in the Spectrum window. This function is used to reduce an excessive wavenumber range. If this function is used by mistake, the original spectrum can be restored outside the LWW program. After using the Crop Spectrum function and saving the spectrum, the original spectrum file is backuped into a file with the .sp0 extension. Therefore restoring the original spectrum is done by copying the file with the .sp0 extension back to the file with the .spe extension.
• Invert – this function toggles between displaying the spectrum in the absorption or transmission scale. For a proper function of the Loomis-Wood diagrams, namely making the height of peak symbols correspond to absorption intensities, the spectrum should be converted into the absorption scale.
• Normalize – this function normalizes the transmission / absorption scale of the spectrum file (described in detail in the Spectrum file section) to the range between 0 and 1.
• Horizontal shift – This is only an intermediate function moving the displayed spectrum in the wavenumber scale with respect to the peak list file. It can be used locally to correct the discrepancy between the spectrum and peak list file in case when the calibration is not done properly. Because it does not correspond to the correct recalibration of Fourier-transform spectra by a multiplicative factor, it should be used only with great care.

The additional Copy to Clipboard command copies the section of the spectrum displayed in the Spectrum window to the clipboard for pasting in any external program.