FWF - Elektronenmikroskopische Detektion - Mapping plasmons of designed nanostructures with an electron beam

The optical local density of states (LDOS) near to a metal nanoparticle gives detailed information about the interaction of light with the particle which is - besides other parameters - defined by the shape of the particle. In the last years it has been shown that laterally resolved electron energy loss spectroscopy (EELS) and energy filtered transmission electron microscopy (EFTEM) are techniques to map these near fields with lateral resolution on the nanoscale. However, up to now EELS and EFTEM measurement were performed at colloidal particles only which grow in a limited variety of shapes. It is the aim of this project to make particles of virtually any shape available for these measurement techniques by introducing electron beam lithography (EBL) a highly flexible technique for preparation of designed nanostructures. The thereby expected challenge is to get the EBL prepared nanostructures onto ultra thin (a few tenth of nanometers) substrates necessary for EELS/EFTEM. We want meet this challenge by developing a novel type of transfer process. The first designed structures to be investigated with EELS/EFTEM will be pairs of particles (particularly dipole and bowtie antennas) and nanorings. In the case of particle pairs we target to map the LDOS in the gap between the particles which is supposed to be dramatically enhanced with respect to the vacuum LDOS, in the case of nanorings we aim to identify a localized particle plasmon polariton (LSPP) mode with a noteworthy magnetic dipole moment by comparison of calculated and experimental LDOS maps.