The Lise Meitner project (M 2787-N) examined CO adsorption on metal surfaces by combining laser spectroscopy with surface science methods. As a first major result, CO adsorbed on smooth/perfect Ir(111) was found to be tilted at high coverage but upright at low coverage, analyzed by combined sum frequency generation (SFG) spectroscopy and density functional theory (DFT) calculations. However, on rough/defective surfaces, the CO tilt angle had only weak coverage-dependence and CO preferred being upright. CO can adopt three different overlayer structures characterized by low energy electron spectroscopy (LEED):  and diffuse at low exposure, and  at high exposure/pressure. The former two overlayer structures have been often reported, while the latter one has been rarely observed.  Further studies, also including X-ray photoelectron spectroscopy (XPS) and LEED indicated that CO dissociation does not occur at low pressure/high temperature or high pressure/low temperature. However, after heatup (room temperature to ~600 K) and cooldown (~600 K to room temperature) in a background of high pressure CO, the obtained irreversible SFG spectra implied that CO dissociated on both the smooth and defective Ir(111), yielding carbon deposits. SFG spectra upon carbon oxidation and XPS spectra of Ir(111) after annealing in CO at ~600 K indirectly and directly confirmed the formation of surface carbon species, respectively. DFT calculations suggested that at high CO partial pressure and thus high CO surface coverage, adsorbed surface CO can react with gas phase CO at increasing temperature via disproportionation (Boudouard reaction 2CO ↔ CO2 + C), forming CO2 and leaving a C atom behind on the Ir surface. A graphene (GR) monolayer was successfully grown on Ir(111) by thermal decomposition of ethylene. Characterization by LEED evidenced a complete continuous GR-layer because no CO intercalation was observed in SFG spectra at several mbar pressure, further confirmed by LEED patterns of GR/Ir(111). After 10s Argon ion sputtering, the LEED patterns of GR became fuzzy, indicating damage. However, upon exposing several mbar CO on sputtered GR/Ir(111), no CO signal was observed in SFG. This demonstrates that even a damaged structure of graphene fully covers the Ir surface, preventing CO adsorption. The GR/Ir(111) surface is currently used as a substrate for the growth of Pd nanoparticles.