Figure 4: Experimental observations of quantum mechanical effects in plasmonic dimers.
From: Quantum mechanical effects in plasmonic structures with subnanometre gaps
(a) Simultaneously measured electrical conductance (G/G0) and dark-field scattering of the AFM dimer shown in Fig. 3a with increasing force applied to the inter-tip cavity after snap-to-contact. The bonding plasmon modes are labelled as A, B and C. The CTP modes are labelled as D and E. (b) QCM and (c) local classical model simulations of the tip-based dimer. The colour scales in a–c represent relative scattering intensities. (a–c) Reproduced from ref. 67. Copyright 2012 Nature Publishing Group. (d) EELS spectra of the Ag dimers shown in Fig. 3b as the gap distance changes from 7 Å to –1 nm. STEM images (top panels) collected at the beginning and end of each scan (highlighted by white solid vertical lines) indicate the gap distances of +7 Å,<2.7 Å, −3 Å and −1 nm from right to left. Reprinted with permission from ref. 68. Copyright 2013 American Chemical Society. (e) Dark-field scattering spectra of the EBL-fabricated Au nanodisk dimers shown in Fig. 3c with various gap distances. Reproduced from ref. 70. Copyright 2014 Nature Publishing Group. (f) Peak wavelengths (green circles and blue diamonds) of the dark-field scattering spectra of the particle-on-film structure shown in Fig. 3e as a function of gap distance. Wavelengths deviate from expectations of local classical simulations (black dashed line) at small gap distances, but can be explained with nonlocal models (solid red line). Error bars represent the uncertainty in determining the wavelength of the plasmon resonance peak. Image reproduced from ref. 32. Copyright 2012 AAAS.
