Electrostatic effects between adsorbed species—the K … Co interaction on Ni(111) as studied by infrared reflection-absorption spectroscopy

Abstract

Using infrared reflection-absorption spectroscopy (IRAS), TPD and LEED, we have made a detailed study of CO coadsorbed with potassium on Ni(111). Both long range delocalized and short range localized potassium-CO interactions are observed at both low and high potassium coverages. Using the high resolution of IRAS, we estimate the lateral range of the long range K-CO interaction to be ≈ 25 CO molecules per potassium atom at the lowest potassium coverage studied. We explain the long range K-CO interaction in terms of a through-space electrostatic interaction and the observed decrease in the CO vibrational frequency in terms of the vibrational Stark effect. Finally, short range K-CO interactions, possibly due to the formation of a potassium-CO complex, are suggested by TPD and IRAS results.