The n³P₂-1¹S₀ Magnetic-Quadrupole Transitions of the Helium Sequence

Accurate variational calculations are presented for the 23P2-11S0 magnetic-quadrupole decay rates of the heliumlike ions He I to Ne IX. It is shown that Z-expansion results for 1P1S electric-dipole transitions are easily modified to obtain the Z-expansion of the corresponding 3P-'S magnetic-quadrupole transition. The Z-expansion parameters are presented for the n~P2-1'S0 transitions, with n = 2(1) 20