Orbital Angular Momentum and Energy Loss Characterization of Plasmonic Excitations in Metallic Nanostructures in TEM

Abstract

KEYWORDS. Plasmonics, electron energy loss spectroscopy, electron orbital angular momentum, transmission electron microscopy.ABSTRACT. Recently, a new device to measure the Orbital Angular Momentum (OAM) electronic spectrum after elastic/inelastic scattering in a transmission electron microscope has been introduced. We modified the theoretical framework needed to describe conventional low

Exploring the Spatial Features of Electronic Transitions in Molecular and Biomolecular Systems by Swift Electrons

“…All simulations have been carried out keeping the collecting angle fixed to 200 mrad and the beam energy to 60 keV, whereas the loss probability has been determined in the angular momentum range of [−3:3]. In order to obtain doubled resolved spectra that simulate the limited instrumental resolution (Δ E = 0.1 eV, Δ l = 0.5 ℏ ), we have performed a convolution of OAM-EELS rates with the product of two Gaussian functions, following the procedure outlined in the Supporting Information of ref ( 32 ).…”

“… 27 , 28 As a matter of fact, even if the measure of the OAM spectrum of a light beam was demonstrated experimentally 10 years ago, 29 only recently has the electronic analogue been made possible by devices based on electrostatic phase elements for measuring and spatially dispersing the different electrons’ OAM components. 30 , 31 Our work is inspired by what has been proposed in the field of metallic nanostructures, 32 here extended to treat molecular and supramolecular systems. In the following, we describe how to modify the configuration of a TEM-EELS apparatus and how to encode a quantum chemistry treatment of the molecular systems and its interaction with the structured wave of the swift electron to obtain OAM resolved EELS spectra, then simulations of the expected experimental results will be presented in a number of paradigmatic cases considering also the effects of the finite resolutions in both energy and OAM due to a nonideal setup.…”

Probing the electromagnetic response of dielectric antennas by vortex electron beams

“…VEBs carry orbital angular momentum (OAM), which could facilitate direct interaction of the beam with excitations of both electric and magnetic nature. Besides various applica-tions in probing magnetic fields 36,37 , magnetic transitions in bulk materials [38][39][40][41] and chirality of crystals 42 , the introduction of VEBs (and other shaped beams) in electron microscopy might also open a pathway for symmetry-based selective excitation of EM modes in photonic nanostructures [43][44][45] , separation of electric and magnetic modes 46 , or for developing the local investigation of the dichroic response of chiral nanoantennas 45,47 .…”

Combination of Electron Energy-loss Spectroscopy and Orbital Angular Momentum Spectroscopy. Applications to Electron Magnetic Chiral Dichroism, Plasmon-loss, and Core-loss

“…CNR -Istituto Nanoscienze, Modena, Emilia-Romagna, Italy, 2 Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich, Nordrhein-Westfalen, Germany, 3 Università di Modena e Reggio Emilia, Modena, Emilia-Romagna, Italy, 4 University of Ottawa, Ottawa, Ontario, Canada, 5 Forschungszentrum Juelich, Juelich, Nordrhein-Westfalen, Germany Electron energy-loss spectroscopy (EELS) is a powerful technique for measuring the energy state of electrons after scattering. It has had incredible success in measuring the atomic and chemical properties of materials, allowing chemical maps to be recorded with atomic spatial resolution.…”

“…Beyond EMCD, we believe that there are prospects to use the same idea for the analysis of plasmon resonances [4] and core transitions. Figure 2 shows an advantage of applying OAM sorter to 2D anisotropic materials (h-BN, graphene, …).…”