Electric-dipole, electric-quadrupole, magnetic-dipole, and magnetic-quadrupole transitions in the neon isoelectronic sequence

Abstract

Excitation energies for $2l\ensuremath{-}{3l}^{\ensuremath{'}}$ hole-particle states of Ne-like ions are determined to second order in relativistic many-body perturbation theory (MBPT). Reduced matrix elements, line strengths, and transition rates are calculated for electric-dipole $(E1),$ magnetic-quadrupole $(E2),$ magnetic-dipole $(M1),$ and magnetic-quadrupole $(M2)$ transitions in Ne-like ions with nuclear charges ranging from $Z=11$ to 100. The calculations start from a ${1s}^{2}{2s}^{2}{2p}^{6}$ closed-shell Dirac-Fock potential and include second-order Coulomb and Breit-Coulomb interactions. First-order many-body perturbation theory (MBPT) is used to obtain intermediate-coupling coefficients, and second-order MBPT is used to determine the matrix elements. Contributions from negative-energy states are included in the second-order $E1,$ $M1,$ $E2,$ and $M2$ matrix elements. The resulting transition energies are compared with experimental values and with results from other recent calculations. Trends of $E1,$ $E2,$ $M1,$ and $M2$ transition rates as functions of nuclear charge Z are shown graphically for all transitions to the ground state.