Comparative study of thermal and photo-induced reactions of NO on particulate and flat silver surfaces

► Thermal and photochemical evolution of (NO)2 on Ag(111) and Ag nanoparticles (NPs). ► Desorbed NO detected from NO dimers and from NO monomers formed photochemically. ► On NPs strong enhancement by plasmon excitation and by excitation confinement. ► But photo-induced dynamics unchanged as translational energies are the same. ► Relative amounts and reactivities of dimers and monomers differ on the two materials.