Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 78: Plasmonics and Nanooptics 3
O 78.2: Vortrag
Freitag, 9. September 2022, 10:45–11:00, H3
Impact of atomistic structure and dynamics on inelastic light scattering in a plasmonic picocavity — •Franco Bonafé1, Shuyi Liu2, Heiko Appel1, Martin Wolf2, Takashi Kumagai2,3, and Angel Rubio1 — 1MPI for Structure and Dynamics of Matter, Hamburg, Germany — 2Dpmt. of Physical Chemistry, Fritz-Haber Institute, Berlin, Germany — 3Center for Mesoscopic Sciences, Institute for Molecular Science, Okazaki, Japan
Atomically sharp metallic tips can focus an electromagnetic field down to the sub-nanometer scale, leading to strong light-matter interactions in plasmonic ``picocavities''. This atomic-scale field can be used in plasmon-enhanced spectroscopy, such as tip-enhanced Raman spectroscopy (TERS), which has enabled the visualization of optical properties at sub-molecular resolution. However, a full microscopic understanding of the interplay of structural relaxation, bonding, near-fields and vibrations has not been achieved.
In this work, we combine experimental observations of inelastic light scattering from a single silver adatom in a plasmonic picocavity controlled by a low-temperature scanning tunneling microscope (STM), with ab initio real-time electron dynamics simulations. The experiment demonstrates a dramatic enhancement of Raman scattering that occurs upon the formation of a quantum point contact. We model possible geometries for the plasmonic tips and compute the vibrational modes, electronic current and near-fields localized in the vicinity of the single adatom. These simulations reveal a crucial role of the atomistic structural relaxation in the optical response in a plasmonic nanocavity.