Silver and oxygen: Transition from clusters to nanoparticles

By varying the sizes of isolated and charged silver particles, we may observe a wide range of reactions from weak molecular-oxygen physisorption to strong oxygen chemisorption. The global electron configuration dominates the stability of the silver–oxygen complexes. Our experimental studies at 77 K show a cluster regime below 40 free valence electrons in the system. Here each atom of silver added to the complex cause strong alternations of the oxygen binding by quantum effects. Bigger silver–oxygen complexes show smoother size dependence. As is rather typical for nanoparticles, the quantum effects are here less important, while the system size still matters. The electrostatic interaction between the charge state of the nanoparticle and the charge transfer of the reaction accounts for the general trends observed at silver, as it is in related oxygen–metal complexes