SpectraPLOT: Band Intensity Plots

Band Intensities plot windows support displaying intensities, frequency-integrated over a Spectral Band, and line widths as a function of time or position on the detector pixel grid.

When adding a new plot window for Band Intensities, the setup panel is displayed with the Band Properties box visible (see below). The following quantities are specified:

• Y-quantity:
  • Frequency-integrated intensity
  • Frequency-integrated fitted intensity
  • Fitted line width
  • Spectral intensity
  • Fitted intensity
  • Fitted background continuum
• Band name or Band Ratio name:
  • Choose from a list of Bands or Band Ratios set up by the user (see below)
• X-quantity
  • Time
  • Pixel dimension (when space-resolved spectra are available)
• Spectral data type:
  • Space-integrated (over all detector pixels)
  • Space-resolved

Spectral bands and ratios are set up by the user. To add to or edit the list of bands, click on the View Bands button.

In the Spectral Bands setup widget (see below), the lists of Spectral Bands and Spectral Band Intensity Ratios are shown.

When the Update Table Values button is pressed, the band intensities, along with fitted intensity and fitted band width (if fitting is used), are displayed.

To add a new Spectral Band to the list, click on the Add button in the Spectral Bands box, and the Set Spectral Band Parameters box is displayed. In the simplest case when no fitting to the data is used, just the minimum and maximum photon energy need to be set. Band intensities are computed by numerically integrating the calculated spectrum between these two photon energies.

Fits to the spectral band can also be obtained. In this case, both the intensity and the width are computed. Options include fitting to a Gaussian profile or a Voigt profile. When a Voigt profile is used, the Voigt parameter, which controls the ratio of the width of the Lorentzian contribution to the width of the Gaussian contribution, is also specified.

Also when a fit is computed, it is possible to subtract a background continuum. Here, the user a specify a constant value to the continuum, or fit to it use either a polynomial or an exponential function. In either of these cases, the fits to the background are based on the intensity values a frequency points listed in the box at the right.

If two or more Spectral Bands have been defined, the intensity ratios of bands may also be specified. To specify a Band Ratio, click on the Add button in the Spectral Band Intensity Ratios panel. Then select from the list of available bands, and move one or more of them into the Numerator and Denominator boxes. The band intensities of each of the spectral band is computed, and the intensity ratios can be displayed in plots.

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