[Todos] HOY: Coloquios DF - Nicolás Lorente (DIPC), 14hs, Aula Seminario, 2do piso, Pab. I

[Augusto Roncaglia]

COLOQUIOS DEL DEPARTAMENTO DE F�SICA FCEYN - UBA


              En el Aula Seminario, 2do piso, Pab. I,

              Jueves 21/5, 14hs:

              NICOL�S LORENTE

              Centro de Física de Materiales -
               Donostia International Physics Center.


              *Single-molecule spectroscopies with the scanning tunneling
microscope*


Conceptually, the spectral function studies how an injected electron or
hole propagates in a given system with energy resolution revealing the
system's electronic structure. By tuning the bias between a scanning
tunneling microscope (STM) tip and a sample, electrons or holes of
different energies can be injected. The derivative with respect to the
applied bias should yield the wished energy resolution. And indeed, the
conductance is the spectral function in the Tersoff-Hamann picture of STM.
Now, the spectral function contains all possible excitations produced by
the injected particle. Then, the STM grants us access to the excitation
spectra of our substrate.

In this talk, I will review the tantalizing experiments showing the
vibrational spectra of adsorbed molecules, and the theory that permits us
to explain the experiments as well as interpret the spectra. But, not only
vibrations are detected, magnetic excitations have also been revealed. I
will also review experimental data and our simple theory that allows us to
have a quantitative account of the observed data. Finally, the spectral
function also informs on correlations at the atomic scale. The Kondo effect
has been revealed on surfaces by the STM and I will show our efforts to
provide simulations of the many Kondo signals discovered on adsorbed
molecules.
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