# Emission Spectra

Simulating emission spectra requires some special considerations:

- The Initial flag must be set
for the upper manifold of
each state, and clear for the lower manifold of each state. (The Initial flag would typically be set
for the lower manifold only.) PGOPHER
will then use a Boltzmann distribution to calculate the population in
the upper state, and assume no population in the lower state.
- To include the ν
^{3} factor in the intensity calculations
the band origins used must be absolute (i.e. enter 19135 cm^{-1}
rather than 135 cm^{-1}) and the IntensityUnits in the Simulation
object should be set to HzperMolecule.