to main chapter Research fields
To model the tip-sample interaction in the scanning tunnelling m icreoscope we adopt
the viewpoint that a local region, the so called surface molecule, is described
in detail and then embedded in the polarizable environment. We developed a model
hamiltonian for the description of the nanocomplex of atoms and molecules in
the vacuum gap in interaction with two metal surfaces, the tip and the sample.
The model of the surface molecule is solved in the dynamic Hartree-Fock approximation
and the solution provides the quasiparticles (quasielectrons and quasiatoms) which
are measured in different kinds of experiments on surfaces (surface sensitive
spectroscopies, desorption, STM, STS).
The tunnelling current in the STM is evaluated in a many-body dynamic theory of the
charge injection process. The transient localization of the injected electron
in a diffuse affinity resonance on the metal surface and the dynamic response in
the metal leads to an enhanced weight of the affinity resonance at the Fermi level.
The STM images essentially the topography of these resonances which is strongly
corrugated parallel to the metal surface.
Corrugation amplitude of the tunnelling current at constant height above the Al(111)
D. Drakova and G. Doyen, Phys. Rev. B 56, pp R15577-R15580 (1997).
D. Drakova, Rep. Prog. Physics 64, pp 205-290 (2001).