title: Partial photoionization cross sections and angular distributions for double excitation of helium up to the N = 13 threshold.
abstract: Partial photoionization cross sections sigmaN(Egamma) and photoelectron angular distributions betaN(Egamma) were measured for the final ionic states He+ (N > 4) in the region between the N = 8 and N = 13 thresholds (Egamma > 78.155 eV) using the cold target recoil ion momentum spectroscopy technique (COLTRIMS). Comparison of the experimental data with two independent sets of theoretical predictions reveals disagreement for the branching ratios to the various HeN(+) states. The angular distributions just below the double ionization threshold suggest an excitation process for highly excited N states similar to the Wannier mechanism for double ionization.
authors.affiliation: Institut für Kernphysik, Universität Frankfurt, D-60438 Frankfurt, Germany. czasch@atom.uni-frankfurt.de
authors.forename: A
authors.initials: A
authors.lastname: Czasch
authors.forename: M
authors.initials: M
authors.lastname: Schöffler
authors.forename: M
authors.initials: M
authors.lastname: Hattass
authors.forename: S
authors.initials: S
authors.lastname: Schössler
authors.forename: T
authors.initials: T
authors.lastname: Jahnke
authors.forename: Th
authors.initials: T
authors.lastname: Weber
authors.forename: A
authors.initials: A
authors.lastname: Staudte
authors.forename: J
authors.initials: J
authors.lastname: Titze
authors.forename: C
authors.initials: C
authors.lastname: Wimmer
authors.forename: S
authors.initials: S
authors.lastname: Kammer
authors.forename: M
authors.initials: M
authors.lastname: Weckenbrock
authors.forename: S
authors.initials: S
authors.lastname: Voss
authors.forename: R E
authors.initials: RE
authors.lastname: Grisenti
authors.forename: O
authors.initials: O
authors.lastname: Jagutzki
authors.forename: L Ph H
authors.initials: LP
authors.lastname: Schmidt
authors.forename: H
authors.initials: H
authors.lastname: Schmidt-Böcking
authors.forename: R
authors.initials: R
authors.lastname: Dörner
authors.forename: J M
authors.initials: JM
authors.lastname: Rost
authors.forename: T
authors.initials: T
authors.lastname: Schneider
authors.forename: Chien-Nan
authors.initials: CN
authors.lastname: Liu
authors.forename: I
authors.initials: I
authors.lastname: Bray
authors.forename: A S
authors.initials: AS
authors.lastname: Kheifets
authors.forename: K
authors.initials: K
authors.lastname: Bartschat