title: Probing the symmetry of the potential of localized surface plasmon resonances with phase-shaped electron beams.
abstract: Plasmonics, the science and technology of the interaction of light with metallic objects, is fundamentally changing the way we can detect, generate and manipulate light. Although the field is progressing swiftly, thanks to the availability of nanoscale manufacturing and analysis methods, fundamental properties such as the plasmonic excitations' symmetries cannot be accessed directly, leading to a partial, sometimes incorrect, understanding of their properties. Here we overcome this limitation by deliberately shaping the wave function of an electron beam to match a plasmonic excitations' symmetry in a modified transmission electron microscope. We show experimentally and theoretically that this offers selective detection of specific plasmon modes within metallic nanoparticles, while excluding modes with other symmetries. This method resembles the widespread use of polarized light for the selective excitation of plasmon modes with the advantage of locally probing the response of individual plasmonic objects and a far wider range of symmetry selection criteria.
authors.affiliation: EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
authors.forename: Giulio
authors.identifier: 0000-0001-9331-9544
authors.initials: G
authors.lastname: Guzzinati
authors.affiliation: EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
authors.forename: Armand
authors.initials: A
authors.lastname: Béché
authors.affiliation: Laboratoire de Physique des Solides, Univ. Paris-Sud, CNRS UMR 8502, F-91405 Orsay, France.
authors.forename: Hugo
authors.initials: H
authors.lastname: Lourenço-Martins
authors.affiliation: Institut Charles Delaunay-Laboratoire de nanotechnologies et d'instrumentation optique, UMR CNRS 6281, Université de Technologie de Troyes, 10010 Troyes, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Martin
authors.affiliation: Laboratoire de Physique des Solides, Univ. Paris-Sud, CNRS UMR 8502, F-91405 Orsay, France.
authors.forename: Mathieu
authors.identifier: 0000-0001-8858-0449
authors.initials: M
authors.lastname: Kociak
authors.affiliation: EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
authors.forename: Jo
authors.initials: J
authors.lastname: Verbeeck