Two photon photoemission spectroscopy of image states
In 2-photon photoemission a photon from a pulsed laser excites an electron from a state below the Fermi level to an unoccupied intermediate state below the vacuum level. A second photon ionizes the intermediate state. The energy distribution of the photoelectrons yields information on the energetic position and the lifetime of the intermediate state. Image states are bound states of electrons in front of metal surfaces in the potential well, built by the image potential and the surface. They have been studied extensively by 2-photon photoemission. Experimental results on the binding energies of image states on (111) and (100) surfaces of silver, gold, copper and palladium agree with calculations by a 1-dimensional scattering model. The results for iron, cobalt and nickel are not yet understood. Lifetimes of image states between 4 and 180 fs have been measured. Particular emphasis is placed on image states on metal overlayers. Information on film growth and surface morphology has been obtained. Lateral localization and coupling to quantum well states has been observed. Dielectric overlayers have also been investigated.
Bibliographic Reference: Article: Photonic Probes of Surfaces (1995) pp. 347-411
Record Number: 199610170 / Last updated on: 1996-03-01
Original language: en
Available languages: en