Explicit analysis of chaotic behavior in radial and angular motion in doubly excited helium
Y. H. Jiang, R. Puettner, D. Delande, M. Martins and G. Kaindl
Experimental and theoretical total photoionization cross sections of doubly excited He up to the single ionization threshold of He are presented, revealing excellent agreement. All spectra are dominated by principal Rydberg series, what is explained by the observation that the quantity F = N - K is approximately a good quantum number for a large fraction of states. The statistical distributions of nearest-neighbor energy spacings between resonances of Rydberg series with small F approach a Wigner distribution. The results show no indication for a transition to full chaos - i.e. a loss of all approximate quantum numbers - in He.