Effect of cascade transitions on the polarization of light emitted after electron-impact excitation of Zn by spin-polarized electrons

摘要

We investigate the possible effect of cascade transitions from the (4s5p) ~3P_(0,1,2) states to the (4s5s) ~3S_1 state of Zn. The polarization of the light emitted in the subsequent decay to the (4s4p) 3P0,1,2 states has been the subject of recent controversy, with significant disagreement between the experimental data reported by Pravica et al. [Phys. Rev. A 83, 040701 (2011)] and by Clayburn and Gay [Phys. Rev. Lett. 119, 093401 (2017)] in the cascade-free region below ≈7.6 eV incident energy and relatively good agreement above. The cross sections for excitation of the (4s5p) ~3P_(0,1,2) states, as well as higher-lying triplet states, and the linear polarization of the cascade radiation seem too small to produce a significant alignment of the (4s5s) ~3S_1 state, thereby raising additional questions regarding the origin of the relatively large linear polarizations measured above the cascade threshold.