Energy levels (in Ry) of the target states of Ne3 + and comparison with available NIST data 
Table 1. Energy levels (in Ry) of the target states of Ne3 + and comparison with available NIST data . The values with superscript '*' are deduced from the experimental results of the x-ray emission spectrum .
A close-coupling calculation is performed for the photoionization cross section of the high-lying core-excited state 1s2s22p5 1Po of Ne2 + in the energy region of the double K-vacancy resonance 1s02s22p6 1S. The calculation is carried out by using the R-matrix method in the LS-coupling scheme, which includes 27 target states and extensive configuration interaction. The KK-KL x-ray energy, rate and autoionization width of the double K-vacancy state, together with KK-KLL Auger energies and branching ratios of the main channels, are obtained from the cross sections and the contributions of these channels. The calculated resonance energy and x-ray rate are in good agreement with the existing experimental and theoretical results. For the Auger width, our result agrees well with the available experimental result and it is very close to the average of other theoretical data, which shows considerable differences with each other. The Auger energy of the predominate channel KK-KL23L23 2D is in rather good agreement with recent experiments on the Auger spectra. Our branching ratios for the channels KK-KL23L23 2D and KK-KL23L23 2S are larger than the results obtained by the multi-configuration Dirac–Fock method by ~20% on average, which may be due to the coupling of the continuum channels.