Dynamics of O2 photodesorption from metal clusters: A significant difference from bulk behaviour

Photodesorption of O2 from AgnO2- (n = 2, 3, 4 and 8) was studied using TR-PES. Direct O2 photodesorption for n = even and a long-lived excited state for Ag3O2- was observed. Both, direct desorption and long-lived excited states, have not been observed from adsorbate covered metal surfaces, suggesting unique photochemical properties of such small clusters.