title: Radiative decay of doubly excited states in helium below the He+ (N = 2) ionization threshold
abstract: The radiative decay of (1)P(o) doubly excited states in helium has been investigated using a novel apparatus in which metastable atoms and vacuum ultraviolet photons are detected. The intensity ratio of the energetically narrow (sp,2n-)(1)P(o) and (2p,nd)(1)P(o) series to the broader (sp,2n+)(1)P(o) series is strikingly enhanced in comparison with conventional photoabsorption, photoion, or photoelectron measurements using synchrotron radiation. The experimental approach is a new way forward for the study of energetically narrow doubly excited states.
authors.affiliation: Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom.
authors.initials: MK
authors.lastname: Odling-Smee
authors.initials: E
authors.lastname: Sokell
authors.initials: P
authors.lastname: Hammond
authors.initials: MA
authors.lastname: MacDonald