Effects of autoionizing resonances on density-sensitive spectral-line intensity ratios in high-temperature plasmas

We present the results of detailed calculations for the intensity ratios between magnetic-quadrupole and electric dipole radiations that are emitted in the 3p53d→3p6 transitions from highly ionized argonlike ions with nuclear charges in the range 26≤Z≤70. In arriving at our theoretical predictions, the population densities of the radiating 3p53d singly excited fine-structure levels were determined by the application of a collisional-radiative equilibrium model, in which we have systematically and self-consistently incorporated the results of fully relativistic multiconfiguration calculations for the atomic energy-level structure and for the elementary atomic collision and radiation rates. In the determination of the population densities of the 3p53d singly excited fine-structure levels, we have investigated the role of indirect processes involving the 3p54l4l' intermediate autoionizing resonances and the 3p43d2 doubly excited bound states