A basic level of a non-Boltzmann population distribution is available through setting the vibrational temperature,
Tvib,
which affects the relative populations of different vibrionic states. It
is also possible to specify the populations individually, for uses such
as simulating double resonance spectra or nascent population
distributions following reactions. It is also possible to fit these
populations to measured intensities or band contours; see the sections on
Line Intensity Fitting and
Contour Fitting. This process can also be used to simulate and fit time of flight or kinetic energy release spectra; use
IntensityUnits =
PopDist
to ignore transition moments and just plot energy levels with
populations derived as described in this section. Plots against
velocity (in units of cm
-1/2), rather than energy can be obtained by Setting
PlotUnits to
sqrtcm1.
To set up population distributions, either:
- In the constants window, select the relevant manifold; by default
no populations will be set so the parameters area will be empty.
- Right click on an item in the parameters area and select "Add All
Levels"; this will add all the levels of that manifold (within the J range set up) and initialize them using the current Temperature and Tvib to calculate the population.
- You can get a matching table of energy levels and quantum numbers
using the "List" button in the "Levels" window, providing the same
manifold is selected.
or, to add individual levels: