Autoionizing rates for doubly excited 2lnl' states of He-like ions

Energy levels and autoionizing rates of 2lnl' (n = 3-12, l = 0-4) configurations for He-like ions with Z = 4-54 were calculated by using the Z expansion method. Relativistic effects are taken into account using the Breit-Pauli operators. The asymptotic dependence on n of the energy matrix is discussed for 2lnl' states. Intermediate coupling coefficients obtained after diagonalizing the energy matrices were also studied. It was observed that these coefficients change very rapidly with n and Z due to a redistribution of contribution between relativistic and correlation effects. As a result, all other atomic characteristics (radiative and nonradiative transition probabilities, branching ratios) display non-monotonous Z- and n-dependences with maxima and minima. (orig.)