Competing routes for charge transfer in co-adsorption of K and <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">O</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math></span> on graphite

K. M. Hock; J. C. Barnard; R. E. Palmer; H. Ishida

doi:10.1103/PhysRevLett.71.641

Competing routes for charge transfer in co-adsorption of K and $O_{2}$ on graphite

K. M. Hock, J. C. Barnard, R. E. Palmer, and H. Ishida

Phys. Rev. Lett. 71, 641 – Published 26 July 1993

Abstract

We have investigated a model co-adsorption system using electron energy loss spectroscopy. When the dispersed phase of K graphite is exposed to $O_{2}$ at 25 K, the charge donated by the alkali is depleted, as evidenced by a reduction of the surface plasmon energy from ∼320 to ∼130 meV. The co-adsorbed $O_{2}$ species is molecular, with a vibrational frequency consistent with the ${}^{2}Π_{g}$ ground state of $O_{2}^{-}$ . The results demonstrate local transfer of charge from alkali to co-adsorbate, consistent with a simple electrostatic model. By contrast, CO perturbs the K-graphite interaction only weakly.