Monitoring and modifying properties of metal surfaces by electronic surface states

The wave functions of electronic surface states are localized near the surface of solids. Therefore surface states are well suited to monitor the physical and chemical state of the surface. If surface states are (partially) occupied, they contribute to the charge density near the surface and to the total energy of the system. Thus they modify the properties of the surface. The influence is particularly pronounced for processes occurring far in front of the surface, where the charge density caused by “competing” bulk states is low or in cases where the total energy differences are only small. Examples from various fields of surface physics are given where metal surface states can be used to monitor and modify surface properties.