M1 transition probabilities between fine structure components2L J (L ≥ 1)

Spontaneous emission transition probabilities of the magnetic dipole transitions between states of ground state configurations consisting of onenl electron (or a hole) outside a closed shell have been calculated by using relativistic terms of order α² Z ² and using hydrogenic orbitals to calculate the required overlap integrals. The line strengths calculated for the Boron and Fluorine isoelectronic sequences are in excellent agreement with the calculations involving Dirac wavefunctions for all ions uptoZ=60. The maximum difference at the highest value ofZ=92 is about 6%. Our calculated lifetimes for the state 2p ^{5 2} P _1/2 for Fluorine-like Mg IV and Fe XVIII are 5.03 s and 51.7 µs respectively which are in excellent accord with corresponding values 5.00 s and 51.0 µs calculated by using sophisticated configuration interaction wavefunctions within the Breit-Pauli approximation. Our calculated value of lifetime for Thalium-like Pb II is 40.0 ms which is in good accord with the experimental value of 41.2 ms. New results are presented for the highly ionized ions in the Al-like and Cl-like isoelectronic sequences. The present analysis can be exploited for all the ions in the isoelectronic sequences of elements of groups III A, III B VII A of the periodic table.