  We present a generalized frequency redistribution function for the polarized
two-term atom in an arbitrary magnetic field. This result is derived within a
new formulation of the quantum problem of coherent scattering of polarized
radiation by atoms in the collisionless regime. The general theory, which is
based on a diagrammatic treatment of the atom-photon interaction, is still work
in progress. However, the results anticipated here are relevant enough for the
study of the magnetism of the solar chromosphere and of interest for
astrophysics in general.
