1. Non-Coherent Scattering in Stellar Atmospheres
P. Heinzel

4. S=B

36. Multilevel atoms Special new problems
Absorption profile for a two-level atom known, f1=fM (Voigt fct)
For a three-level atom, transition 2 -> 3, NOT known since f2 will differ
from fM due to a selective absorption
Emission profile for transition 3 -> 2 also NOT known, f3 also differs from fM
For CRD we have fi=fM

37. Natural population Spontaneous emission Inellastic collisions
Ionization and recombination
Excitation by frequency-independent radiation
-> i *

38. Generalized redistribution functions
Finite number of atomic levels -> finite number of non-Markovian radiation processes
1*=>2=>3 … =>n->I
GRF describe photon correlations in each sequence of
consecutive radiation transitions of the atom that starts from naturally populated initial level

39. Emission in the transition 3->1 (L)
->3*-> prob{->3*}
1*=>3-> prob{1*=>3}
->2*=>3-> prob{->2*=>3}
1*=>2=>3-> prob{1*=>2=>3}

40. Absorption in the transition 2=>3 (H)
-> 2* => prob{->2*}
1*=>2=> prob{1*=>2}

42. Solution of the transfer problem
Generalized redistribution functions
Multilevel cases
General approach
Solution of the transfer problem
(2-level atom, ETLA, ETLA+LINEAR, MALI)
Applications