Partial cross sections of doubly excited helium below the ionization threshold I{sub 7}

Journal Article · Thu Apr 01 04:00:00 EST 2004 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.69.042706· OSTI ID:20640991

Jiang, Y H ^[1]; Puettner, R; Poiguine, M; Kaindl, G ^[1]; Hentges, R; Viefhaus, J; Becker, U ^[2]; Rost, J M ^[3]

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1. Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin-Dahlem (Germany)
2. Fritz-Haber-Institut Berlin, Faradayweg 4-6, D-14195 Berlin-Dahlem (Germany)
3. Max-Planck-Institut fuer Physik Komplexer Systeme, Noethnitzer Strasse 38, D-01187 Dresden (Germany)

Partial photoionization cross sections (PCSs), {sigma}{sub n}, leading to final ionic states of helium, He{sup +}(n), were measured at BESSY II in the region of doubly excited helium up to the ionization threshold I{sub 7} of He{sup +}. The experiments were performed with a time-of-flight (TOF) electron spectrometer and high photon resolution, {delta}E congruent with 6 meV. The results of these measurements are a most critical assessment of the decay dynamics of double-excitation resonances and agree well with those of recent eigenchannel R-matrix calculations. They also confirm the propensity rules set up for the autoionization of doubly excitated states. The mirroring behavior in the PCSs predicted recently by Liu and Starace is only partially observed. By discussing the formulas given by these authors in a more general context, the specific behavior of the PCSs of helium with respect to mirroring can be understood. The mirroring compensation properties between the 'fractional partial cross sections' {gamma}{sub P}={sigma}{sub P}/{sigma}{sub T} and {gamma}{sub Q}={sigma}{sub Q}/{sigma}{sub T}, with {sigma}{sub T}={sigma}{sub P}+{sigma}{sub Q}, are introduced and discussed.

• OSTI ID: 20640991
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 4 Vol. 69; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ALGEBRA
AUTOIONIZATION
BESSY STORAGE RING
CROSS SECTIONS
DECAY
EIGENFUNCTIONS
EIGENVALUES
ELECTRON SPECTROMETERS
EXCITATION
EXCITED STATES
HELIUM
HELIUM IONS
PHOTOIONIZATION
PHOTON-ATOM COLLISIONS
PHOTONS
R MATRIX
RESOLUTION
RESONANCE
TIME-OF-FLIGHT METHOD