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DS: Dünne Schichten

DS 18: Optische Spektroskopie dünner Schichten I

DS 18.3: Vortrag

Montag, 7. März 2005, 15:45–16:00, TU HS110

The crucial role of surface roughness in SEIRA and SERS — •Annemarie Pucci¹, Andreas Priebe¹, Matthias Lust¹, Gerhard Fahsold¹, and Andreas Otto² — ¹Kirchhoff-Institut fuer Physik, Universitaet Heidelberg, Im Neuenheimer Feld 227, D-69120 Heidelberg, Germany — ²Institut fuer Physik der kondensierten Materie, Universitaet Duesseldorf, Universitaetsstr. 1, D-40225 Duesseldorf, Germany

On atomically rough metal surfaces selection rules for infrared (IR) absorption and for Raman scattering break down; additional vibration lines with increased oscillator strength may appear. Depending on the adsorbate species, the additional lines correspond to molecules with modified bonding (e.g. C2H4 on Cu) or to new chemical species (e.g. N2O and N2 from NO on Cu). Concerning the detection of the new species, surface enhanced IR absorption (SEIRA) and surface enhanced Raman scattering (SERS) show a very different sensitivity, which may be due to the basic differences in the excitation processes of the two methods. Molecules with excited states well above the Fermi energy do not show spectral changes due to the surface roughness.