Photodesorption and work function study of long-living excited electronic states on metal surfaces

Excited electronic states in metals and in the near neighborhood of metal surfaces are commonly believed to have a very short lifetime, typically a femtosecond or even less. In the course of our photodesorption experiments we have found evidence of excited electronic states on a metal surface with a lifetime of about 30 fs. It was proved that this long-living electronic excitation is localized on surface structural defects. From our additional study on the photoelectric work function we can conclude that the surface structural defects have a fractional negative charge. The nature of the long-living excited electronic states and the desorption mechanism are discussed.