Relativistic many-body calculations of E1, E2, M1, and M2 transitions rates for the 1 s 2 l′ 2 l′ ′ – 1 s 2 2 l lines in Li-like ions

Abstract

Reduced matrix elements, oscillator strengths, and transition rates are calculated for all allowed and forbidden 1s2l′ 2l′ ′ – 1s 22l electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions in lithiumlike ions with nuclear charges ranging from Z = 6 to 100. Relativistic many-body perturbation theory (RMBPT), including the Breit interaction, is used to evaluate retarded E1, M1, E2, and M2 matrix elements. The calculations start with a Dirac potential and include all possible 1s2l′ 2l′ ′ configurations, leading to seven odd-parity and nine even-parity states. First-order perturbation theory is used to obtain intermediate coupling coefficients. Second-order RMBPT is used to determine the matrix elements, which are evaluated for the 22, 20, 16, and 18 possible E1, M1, E2, and M2 transitions, respectively. A detailed discussion of the various contributions to the energy levels and E1, M1, E2, and M2 matrix elements is given for lithiumlike iron, Z = 26. The transition energies used in the calculation of oscillator strengths and transition rates are evaluated using second-order RMBPT. Trends of E1, M1, E2, and M2 transition rates as functions of nuclear charge Z are shown graphically for 1s2l′ 2l′ ′ – 1s 22l transitions.