Dissecting the Few-Femtosecond Dephasing Time of Dipole and Quadrupole Modes in Gold Nanoparticles Using Polarized Photoemission Electron Microscopy

Hiroaki Misawa, Yasutaka Matsuo, Atsushi Kubo, Yu Han, Quan Sun

Research output: Contribution to journalArticlepeer-review

70 Scopus citations

Abstract

Dipole and quadrupole modes are the two lowest orders of localized surface plasmon resonance (LSPR) eigenmodes in metallic nanoparticles. Of these two modes, the quadrupole mode is forbidden for symmetric metallic nanoparticles excited by linearly polarized light at normal incidence. Here, we demonstrate excitation of the quadrupole mode in symmetrical gold (Au) nanoblocks shined with s -polarized light at oblique incidence. In particular, we probe the near -field LSPR in Au nanoblocks using photoemission electron microscopy (PEEM) and find that at oblique incidence, the dipole and quadrupole modes can be selectively excited, in terms of near -field enhancement, by manipulating the light polarization state. More importantly, by time -resolved PEEM measurements, we experimentally demonstrate that the quadrupole mode in symmetrical Au nanoblocks has longer dephasing time than that of the dipole mode.
Original languageEnglish
Pages (from-to)3835-3842
Number of pages8
JournalACS Nano
Volume10
Issue number3
DOIs
StatePublished - Mar 2016

Keywords

  • surface plasmon resonance; near-field imaging dephasing photoemission electron microscopy (PEEM); dark plasmon mode

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