Key ingredients of the alkali atom – metal surface interaction: Chemical bonding versus spectral properties.

Highlights: [•] The interaction of alkali adatoms with metal surfaces is reviewed. [•] The relevance of the spectral properties in the bond formation is discussed. [•] It is shown the role of the surface projected band gap in determining the alkali electronic resonance features. [•] A critical overview of different theoretical models gives an unified picture of the alkali atom - metal surface bond. [Copyright &y& Elsevier]