Low energy electron diffraction (LEED) measurements showed a few weak and two sharp patterns (2√2X2√2)R 45° and (√2X√2)R 45° at θK = 0.25 and θK = 0.50 (monolayer), respectively, for the K + CO coadsorbed layer. Preadsorbed potassium markedly increased the activation energy for CO desorption from 128 kJ/mol at θK = 0 to 163 kJ/mol at θK = 0.44 (monolayer). The sticking probability remained constant in the range θK = 0.0-0.30, but radically decreased above this potassium coverage. The work function of the potassium dosed surface (θK = 0.1-0.25) increased sharply following CO adsorption suggesting a high negative charge on CO molecule. A strong electronic interaction between CO and the K/Pd system was also revealed by electron energy loss spectroscopic (EELS) studies. This consisted of a significant decrease in the intensity of the CO loss observed on a clean Pd surface at 12.5-13.0 eV and the simultaneous development of a new loss feature at 24.5-25 eV.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry