AvaRaman Operating manual AvaSoft Raman 7.3 November 2008

2.3.2.6.2 Setup Menu: Options – Full Width Half Max
The Full Width Half Maximum of a peak is the bandwidth for which the intensity is higher than half
of the maximum intensity of that peak. The unit for FWHM is cm -1 if the Raman Shift is displayed at
the X-Axis and nanometer if the wavelength is displayed at the X-axis. This utility is used mostly
measuring the output of laser diodes. During FWHM
calculations, the intensity needs to be corrected for
the dark data. Therefore it is recommended to
enable the option Subtract Saved Dark, as shown in
the dialog at the right, which appears after clicking
the FWHM option. After clicking the OK button, the
Full Width Half Max can be calculated for a number
of peaks.
To mark a peak for which the FWHM values needs to be calculated, press the ALT key, and click
with the left mouse button on this peak. If only one spectrometer channel is enabled, and there are
no earlier saved graphs being displayed, then the FWHM value of the marked peak will be shown
directly on top of the peak. Further on, this peak will be yellow marked over the width of the FWHM
value (it may be necessary to zoom in on the peak to be able to view that the peak is marked).
If more than one spectrum is being displayed, a dialog, as shown at the
right, pops up in which the spectrum for which the FWHM needs to be
activated can be selected out of all displayed spectra.
In the figure below, two peaks have been selected for FWHM
calculation: one for the Master channel and one for
“AVANTES0001.roh”, which is an earlier saved spectrum.
The FWHM values are given in
the same color as the
spectrum is drawn.
To disable the FWHM
calculation, the menu option
(which is marked as long as
the FWHM is enabled), needs
to be reselected.
36 AvaRAMAN manual.doc Nov-08
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