Near Field of Strongly Coupled Plasmons: Uncovering Dark Modes
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- 作者：Florian Schertz ; Marcus Schmelzeisen ; Reza Mohammadi ; Maximilian Kreiter ; Hans-Joachim Elmers ; Gerd Sch枚nhense
- 刊名：Nano Letters
- 出版年：2012
- 出版时间：April 11, 2012
- 年：2012
- 卷：12
- 期：4
- 页码：1885-1890
- 全文大小：288K
- 年卷期：v.12,no.4(April 11, 2012)
- ISSN：1530-6992
文摘
Strongly coupled plasmons in a system of individual gold nanoparticles placed at subnanometer distance to a gold film (nanoparticle-on-plane, NPOP) are investigated using two complementary single particle spectroscopy techniques. Optical scattering spectroscopy exclusively detects plasmon modes that couple to the far field via their dipole moment (bright modes). By using photoemission electron microscopy (PEEM), we detect in the identical NPOPs near-field modes that do not couple to the scattered far field (dark modes) and are characterized by a strongly enhanced nonlinear electron emission process. To our knowledge, this is the first time that both far- and near-field spectroscopy are carried out for identical individual nanostructures interacting via a subnanometer gap. Strongly resonant electron emission occurs at excitation wavelengths far off-resonant in the scattering spectra.