State-resolved valence shell photoionization of Be-like ions: experiment   and theory
  High-resolution photoionization experiments were carried out using beams of Be-like C$^{2+}$, N$^{3+}$, and O$^{4+}$ ions with roughly equal populations of the $^1$S ground-state and the $^3$P$^o$ manifold of metastable components. The energy scales of the experiments are calibrated with uncertainties of 1 to 10 meV depending on photon energy. Resolving powers beyond 20,000 were reached allowing for the separation of contributions from the individual metastable $^3$P$^o_0$, $^3$P$^o_1$, and $^3$P$^o_2$ states. The measured data compare favourably with semi-relativistic Breit-Pauli R-matrix 
A M\"uller, S Schippers, R. A. Phaneuf, A. L. D. Kilcoyne, H.   Br\"auning, A. S. Schlachter, M. Lu and B. M. McLaughlin
astro-ph.EP physics.atom-ph