Weakly bound resonances: electronic structure and partial decay widths of a new He- triply excited P-2(o) resonance

A novel type of He- triply excited resonance is predicted and calculated ac curately. It has P-2(o) symmetry, lies above the well known 2s(2)2p P-2(o) state and is considered as resulting from strong electron correlations in t he intrashell state and from weak binding due to long-range interactions of an s electron with a '2s2p' type core. Its energy is less than 5 meV below that of the He 2s2p P-3(o) resonance, and its width is about 9.5 meV. This fact is explained from an analysis of the wavefunction, together with the fact that the distribution of the partial decay widths peaks at the He 1s5s S-1 epsilonp (2)p(o) channel, due to orbital nonorthonormality. The existe nce of this resonance is in harmony with the 1986 observations of van der B urgt et al (van der Burgt P J M, van Eck J and Heideman H G M 1986 J. Phys. B: At. Mol Phys. 19 2015).