Dielectronic recombination of highly charged ions with spin-polarized electrons

Angular distribution and linear polarization of photon emission following dielectronic recombination of initially lithium-like ions with spin-polarized electrons are studied. In particular, a general expression is derived for the alignment parameter of the doubly excited states produced via the resonant capture of spin-polarized electrons. By means of the alignment parameter, moreover, the angular distribution and linear polarization of the subsequently emitted photons are further obtained. Detailed computations are performed for the $1s^{2}2s{J}_0=1/2+\epsilon e^{-}\to 1s2s^{2}2p_{1/2}J=1\to 1s^{2}2s^2{J}_f=0+\gamma$ resonant electron capture and subsequent radiative decay of iodine ions. It is found that the spin polarization of the incident electrons changes only the $q=\pm 1$ components of the alignment parameter $A_{2q}$. As a consequence, the electron spin polarization contributes weakly to the $\gamma$ photon angular distribution and linear polarization that are dominantly determined by the $A_{20}$ parameter.