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Institute Methods and Instrumentation for Synchrotron Radiation Research


enlarged view

Probing the electronic structure of a glycine molecule
absorbed on a Cu (110) surface allows to disentangle
the contributions to the electronic structure separately
on each of the constituent atoms. The orientation of the
probed orbitals can be selected to be along the x-, y- or
z-axis. Projecting onto the core holes of s-symmetry singles
out the signal from the p-symmetric valence orbitals.
Figure adapted from Nyberg et al., J. Chem. Phys. 112,
5420 (2000)

The combination of RIXS with molecules adsorbed on surfaces is very promising. In contrast to many other methodologies, RIXS can address the valence electronic structure at selected atomic centers. Therefore, RIXS on surface adsorbate systems is mainly unaffected by the underlying passive matrix and can selectively study the system of electronic bonds at the molecule. Through comparison of spectra from free molecules and the adsorbed molecules, the surface bonding can directly be studied and the impact for example on surface mediated catalytic reactions can be evaluated.

Making use of the tuneability to element specific core resonances and the polarization control with respect to the surface orientation can selectively study specific bonds and their evolution while changing different parameters, like surface temperature, adsorption sites and structures, coadsorbates etc.

We are currently enhancing our capabilities of clean surface preparation under UHV conditions for small molecule model systems in combination with a novel RIXS spectrometer setup. This setup will allow for trading resolution with transmission to account for the extremely dilute surface systems, while we still expect a much higher transmission than at current setups.