Wy. Cheng et Kn. Huang, KINEMATIC ANALYSIS OF RADIATION FROM ATOMS AFTER ELECTRON-IMPACT EXCITATION, Journal of physics. B, Atomic molecular and optical physics, 28(8), 1995, pp. 1547-1567
The polarization of the emitted photon from an atom or ion after elect
ron-impact excitation is related to that of the incident electron by m
aking use of rotation and parity symmetries. Explicit formulas for the
angular distribution and polarization of the photon are derived in te
rms of angle-independent dynamic parameters by using the helicity form
ulation of the collision processes. Physical interpretations of the fi
ve independent dynamic parameters in the electric dipole approximation
are presented. Conditions for emitting completely polarized photons a
re given.