Regensburg 2019 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 93: Plasmonics & Nanooptics VI: Near-Field Microscopy and Phenomena

O 93.1: Vortrag

Freitag, 5. April 2019, 10:30–10:45, H8

Electron near-field circular dichroism — •Tyler Harvey, Jan-Wilke Henke, Ofer Kfir, and Claus Ropers — IV. Physical Institute: Solids and Nanostructures, University of Göttingen, Germany

Circular dichroism spectroscopy with visible light and x-rays has long been used to characterize chiral-structured materials, magnetic materials, and chiral electronic transitions. In this presentation, we demonstrate a nanometer-resolution circular dichroism technique that employs electrons to probe optical near fields. Electron near-field circular dichroism offers nanoscale insight into chirality.

Electrons can absorb or emit integer multiples of the photon energy from an optical field adjacent to a surface [1,2]. The strength of the coupling between the electron momentum and the optical field amplitude depends on the shape and optical properties of the surface. Because electron beams can be focused to sub-nanometer spots in modern electron microscopes, this interaction, called photon-induced near-field electron microscopy (PINEM) can be employed to image plasmonic modes and optical properties with nanometer spatial resolution. By illuminating a sample with left- and right-circularly polarized light and measuring the difference in coupling strength with electrons, we probe chiral optical near fields with nanometer spatial resolution. This technique may enable the investigation of chiral optical and electronic states in plasmonic nanostructures, molecules and atoms with sub-nanometer spatial resolution.

[1] B. Barwick et al., Nature 462 (2009) 902.

[2] A. Feist et al., Nature 521 (2015) 200.