4.1. Testcase #1
In this example we calculate the population ratios of the
3PJ ground levels of
atomic carbon as a function of neutral hydrogen density. These
population ratios are a useful density estimator
[19]
and are needed
to interpret ratios of UV C I fine structure absorption lines observed
in damped
Lyman-
QSO absorbers
[20,
21,
22],
for example.
We take into account collisions with several collisional partners - electron, proton, neutral hydrogen, para/ortho molecular hydrogen, neutral helium -, tying their densities to the neutral hydrogen density nH0 according to:
We also take into account the effect of CMBR at a redshift z = 1
and the radiation field of the Galaxy.
In the high density limit, function LTEDEV is called to show that the
population ratios differ
from LTE conditions by less than 4% .
To run this testcase the user should include the radiation field of the
Galaxy in the body
of function URAD in module POPRATIO:
urad = Fgal(lambda)
