L.A. Vainshtein and U.I. Safronova 1978, ADNDT 21, 49 "Wavelengths and Transition Probabilities of Satellites to Resonance Lines of H- and He-like Ions" Table V He-like ion: Z= 21 lower level upper level lambda(A) Qd(1/s) Ar(1/s) Aa(1/s) Branching-ratio 1s2p 3P 1.0 2p2p 1S .0 2.7310 1.14E+10 9.18E+10 2.81E+13 4.05E-04 1s2s 3S 1.0 2s2p 1P 1.0 2.7372 2.98E+12 1.60E+12 2.00E+14 4.97E-03 1s2p 1P 1.0 2p2p 1S .0 2.7436 2.46E+13 1.98E+14 2.81E+13 8.75E-01 1s2p 3P 1.0 2p2p 1D 2.0 2.7495 1.63E+11 5.72E+10 3.19E+14 1.02E-04 1s2s 1S .0 2s2p 1P 1.0 2.7520 2.24E+14 1.20E+14 2.00E+14 3.73E-01 1s2p 3P 2.0 2p2p 1D 2.0 2.7528 7.50E+13 2.63E+13 3.19E+14 4.70E-02 1s2s 3S 1.0 2s2p 3P 2.0 2.7552 6.12E+13 1.20E+14 1.36E+13 8.98E-01 1s2p 3P 1.0 2p2p 3P 2.0 2.7564 6.12E+13 6.61E+13 5.44E+13 2.25E-01 1s2s 3S 1.0 2s2p 3P 1.0 2.7590 4.20E+13 1.18E+14 1.61E+13 8.69E-01 1s2p 3P 2.0 2p2p 3P 2.0 2.7599 1.42E+14 1.53E+14 5.44E+13 5.22E-01 1s2s 3S 1.0 2s2p 3P .0 2.7604 1.22E+13 1.19E+14 1.36E+13 8.97E-01 1s2p 3P 1.0 2p2p 3P .0 2.7610 2.11E+12 2.29E+14 2.16E+12 9.80E-01 1s2p 1P 1.0 2p2p 1D 2.0 2.7622 6.09E+14 2.13E+14 3.19E+14 3.82E-01 1s2p 1P 1.0 2p2p 3P 2.0 2.7692 1.84E+13 1.99E+13 5.44E+13 6.78E-02 1s2p 1P 1.0 2p2p 3P .0 2.7738 2.25E+10 2.44E+12 2.16E+12 1.04E-02 1s2s 1S .0 2s2p 3P 1.0 2.7740 5.56E+11 1.56E+12 1.61E+13 1.15E-02 1s2p 3P 1.0 2s2p 1S .0 2.7773 8.20E+12 9.34E+12 3.31E+14 2.48E-02 1s2p 1P 1.0 2s2p 1S .0 2.7903 3.20E+13 3.64E+13 3.31E+14 9.66E-02