Numéro |
J. Phys. IV France
Volume 09, Numéro PR6, June 1999
International Conference on Coincidence Spectroscopy
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Page(s) | Pr6-127 - Pr6-132 | |
DOI | https://doi.org/10.1051/jp4:1999629 |
J. Phys. IV France 09 (1999) Pr6-127-Pr6-132
DOI: 10.1051/jp4:1999629
Two electron photoemission processes in the valence band of solids
R. Herrmann, S. Samarin, H. Schwabe and J. KirschnerMax-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle (Saale), Germany
Abstract
We present experimental evidence on photo double ionization processes in the valence band of
solids. Applying a 'Time-of-Flight' electron spectroscopy technique, we measured the energy distribution
of pairs of correlated electrons emitted from clean Cu(001)- and Ni(001)- crystals upon absorption of
linearly polarized photons of 45eV energy. Data were taken for normal and grazing orientation of the
light wave vector with respect to the crystal surfaces. The energy sharing distributions of electron pairs
emitted from the vicinity of the Fermi-level show significant differences for Cu and Ni. For interpretation
of our data, we consider a direct double ionization mechanism in competition with a two step process
involving single photoexcitation and a subsequent collision of the photoelectron with an additional band
electron. A theoretical approach by J. Berakdar including both mechanisms is in good agreement with
our data. In this theory the differences between Cu and Ni are traced back to distinct relative
contributions of both mechanisms in the two metals due to the different average electron density.
© EDP Sciences 1999