Polarization measurements on a magnetic quadrupole line in Ne-like barium

This is the authors' abstract. We don't add key points for this paper.

We have measured the absolute polarization of the 2p⁶¹{S}₀$-2${p}⁵(²{P}3/2ᵒ$)3s[3/2${]}₂ᵒ$ magnetic quadrupole transition in Ne-like barium, excited in an electron-beam ion trap at a variety of energies. We find strong evidence for the existence of resonant excitation processes that are not explained by our collisional-radiative calculations even when the polarization arising from impact excitation is included. At energies well away from where the resonances occur, the agreement between experiment and theory is good. {} 1996 The American Physical Society.