Near-threshold core photoionization of Ne

A.L. Landers
(Auburn Univ.),

Th. Weber, M.H. Prior
(Lawrence Berkely Nat. Lab.),

T. Osipov, C.L. Cocke
(Kansas State Univ.),

M. Weckenbrock, M. Schöffler, S. Voss, H. Schmidt-Böcking, R. Dörner
(IKF Univ. Frankfurt)

We have measured core photoexcitation and photoionization of Ne atoms near the 1s ionization threshold. Linearly polarized photons ranging in energy from 868 eV to 872 eV at E/\Delta E = 1000 were used at BL-9.3.2 of the LBNL Advanced Light Source in conjunction with a momentum imaging technique (COLTRIMS). Momentum spectra for low energy electrons exhibit two distinct features: 1) Isotropic rings of discreet energy are attributed to Koster-Kronig type emission following direct excitation to Rydberg states just below the ionization threshold and/or recapture of the 1s photoelectron into such states following Auger decay. 2) An underlying dipole-like distribution continuous in energy is attributed to direct photoionization followed by retardation associated with the rapid charge change that accompanies the Auger decay of the core hole. Analysis is underway to use correlated measurements of the associated recoiling Ne^2+ ion to clearly discern these individual “post-collision” processes.

This work was supported by the Chemical Sciences, Geosciences and Biosciences Division,
Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

Submitted to DAMOP, May 2004 in Tucson, AZ.

 

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