Reduction of the Low-Energy Electron Reflectivity of Ag(100) upon Adsorption of Cobalt Phthalocyanine Molecules

Abstract

Using the retarding field diode method for detection of the work function changes, we explore the low-energy electron (0 to 3 eV) reflectivity of Ag(100) covered with a layer of CoPc molecules. The molecular layer significantly reduces the electron reflectivity from the sample surface. The maximum of the sample current, which is associated with minimum of electron reflectivity is observed for 1 ML of CoPc. The reflectivity is diminished from above 50% for the clean sample to almost 20% for the coverage of 1 ML. Additionally, we show that the large change in reflectivity greatly influences the determination of changes in work function (Δϕ) when the retarding field diode method is used without normalization to the saturation currents of each I–V diode curve.