Photo-double-ionization of He-like and Be-like systems in excited states within an intermediate-energyR-matrix framework

Abstract

In this article we apply the intermediate-energy R-matrix method to photo-double-ionization of the metastable 1s2s 1,3 S e and 1s2p 1,3 P o states of He, O 6+ , and Ne 8+ , along with the 1s 2 2s2p 1,3 P o and 1s 2 2s3s 1,3 S e states of Be, O 4+ , and Ne 6+ . We compare our results with other theoretical data where possible and achieve excellent agreement. We examine trends between the various excited states and ground states of the systems.