Mixed-valence correlations in charge-transferring atom–surface collisions

Author: Pamperin M   Bronold F X   Fehske H  

Publisher: IOP Publishing

E-ISSN: 1402-4896|2015|165|14008-14016

ISSN: 1402-4896

Source: Physica Scripta, Vol.2015, Iss.165, 2015-10, pp. : 14008-14016

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Abstract

Motivated by experimental evidence (He and Yarmoff 2010 Phys. Rev. Lett. 105 176806) for a mixed-valence state to occur in the neutralization of strontium ions on gold surfaces we analyze this type of charge-transferring atom–surface collision from a many-body theoretical point of view using quantum-kinetic equations together with a pseudo-particle representation for the electronic configurations of the atomic projectile. Particular attention is paid to the temperature dependence of the neutralization probability which—experimentally—seems to signal mixed-valence-type correlations affecting the charge-transfer between the gold surface and the strontium projectile. We also investigate the neutralization of magnesium ions on a gold surface which shows no evidence for a mixed-valence state. Whereas for magnesium excellent agreement between theory and experiment could be obtained, for strontium we could not reproduce the experimental data. Our results indicate mixed-valence correlations to be in principle present, but for the model mimicking most closely the experimental situation they are not strong enough to affect the neutralization process quantitatively.