Influence of Bulk States on Laterally Confined Surface State Electrons

Abstract

Strong scattering by adatoms positioned with the tip of a scanning tunneling microscope (STM) has recently been used to confine surface state electrons to nanoscale structures. We develop a model for confinement by a circular potential on a metal surface, including substrate band structure effects. Scattering into bulk states provides an important broadening mechanism for partially confined states. Contrary to experiment the level width vanishes as the energy approaches the surface state band edge, indicating an additional dominant broadening mechanism for laterally confined surface state levels seen in the STM.

Decay of electronic excitations at metal surfaces

“…Fig. 32 demonstrates the importance of the self energy in determining the peak amplitudes and widths in the LDOS [200,201]. The calculation for vanishing G, i.e.…”

“…The calculations were extended to include an energy-dependent lifetime of the electronic states. Since strong coupling to bulk states occurs at the adatoms [200] they were modeled as perfectly absorbing scatterers. Fig.…”

Scattering Theory of Kondo Mirages and Observation of Single Kondo Atom Phase Shift

“…In this picture, the scattered electron wave, and therefore the STM signal, are determined by a single quantity: the s-wave phase shift of the scattered wave, δ o (ǫ), which will typically by complex. The imaginary part of the phase shift represents "absorption" (incoherent scattering of electrons) by the adatoms which tend to couple surface states to bulk states [5,9,10] resulting in a loss of electrons from the surface states.…”

Nanoscale Quantum Laboratories

“…Similar conclusions were reached by Avouris and Lyo for step edges. These empirical findings are backed up by theore tical work on the quantum corral done by Simon Crampin (Cambridge) and Mike Boon and John Inglesfield (Nijmegen) [10], as well as calculations made at Imperial College for a variety of added rows and step edges. The quality factor Q of a cavity gives a measure of the lifetime of resonances in the cavity.…”