Welcome, Willkommen, Bienvenu
to the homepage of Dr. Marcus Schmelzeisen
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My Ph.D. project in the material science group of the MPI-P:
Sphere-on-plane resonators are composed of a metal sphere with a diameter in the range of 50-100 nm which are separated from a metal surface by a thin gap, typically less than 5% of the particle diameter. Here, optical resonances are seen that are strongly red-shifted with respect to the resonance of the sphere alone and are expected to exhibit a tremendous near field enhancement in the gap.
Fig. : Sphere-on-Plane-Geometry and resulting optical resonances due to the interaction of the sphere and the plane.
In real systems, though, metal crystals are used that do not have perfectly spherical shape, at the same time metal surfaces and spacer layers are necessarily not perfect. For this reason, large individual differences between real sphere-on-plane resonators are to be expected and a single-object investigation is mandatory.
We developed a highly efficient dark-field mode, exploiting the intermediate excitation of surface plasmons which allows high quality dark field micrographs through a thin metal film, and therefore the spectroscopy on individual resonators.
Furthermore, identification of individuals in high-resolution scanning electron microscopy, atomic force microscopy and optical microscopy allows for a full characterization of the optical response and the shape of the particles.
