Dynamics of two-electron excitations in helium

Technical Report · Tue Apr 01 04:00:00 EST 1997

DOI:https://doi.org/10.2172/603601· OSTI ID:603601

Caldwell, C. D.; Menzel, A.; Frigo, S. P. ^[1]

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1. Univ. of Central Florida, Orlando, FL (United States); and others

Excitation of both electrons in helium offers a unique window for studying electron correlation at the most basic level in an atom in which these two electrons and the nucleus form a three-body system. The authors utilized the first light available at the U-8 undulator-SGM monochromator beamline to investigate the dynamic parameters, partial cross sections, differential cross sections, and photoelectron angular distribution parameters ({beta}), with a high resolving power for the photon beam and at the highly differential level afforded by the use of their electron spectrometer. In parallel, they carried out detailed calculations of the relevant properties by a theoretical approach that is based on the hyperspherical close-coupling method. Partial photoionization cross sections {sigma}{sub n}, and photoelectron angular distributions {beta}{sub n} were measured for all possible final ionic states He{sup +}(n) in the region of the double excitations N(K,T){sup A} up to the N=5 threshold. At a photon energy bandpass of 12 meV below the thresholds N=3, 4, and 5, this level of differentiation offers the most critical assessment of the dynamics of the two-electron excitations to date. The experimental data were seen to be very well described by the most advanced theoretical calculations.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 603601
• Report Number(s): LBNL--39981; ON: DE97007345; CNN: Grant PHY-9207634; Grant PHY-9507573
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ANGULAR DISTRIBUTION
DIFFERENTIAL CROSS SECTIONS
ELECTRON CORRELATION
EXCITATION
HELIUM
PHOTOELECTRON SPECTROSCOPY
PHOTOIONIZATION