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Four distinct EELS spectra taken from regions of Au, Si, silica, and Au/silica interface (solid-line: Au, open square-line: Au/silica interface, triangular-line: Si, and open circular-line: silica) marked in the HAADF image of the Au/silica nanowire shown as inset.
(a) STEM HAADF image of the Au/silica nanowire marked with positions (A to F) where the spectra in (b) were obtained. (b) Position-dependent STEM-EELS spectra, in the 1–6 eV spectral regime taken from positions A, B, C, D, E, and F which is 0 nm, 3 nm, 9 nm, 20 nm (silica/vacuum interface at D), 25 nm, and 30 nm from the Au/silica interface, respectively. Spectra denoted as Ac, Bc, and Cc are corresponding the spectra after the thickness correction. Spectra D, E, an F requires no thickness correction since no silica layer is involved. The inset in (b) shows the EELS spectra over the energy range of 1–25 eV.
(a) The unprocessed and (b) thickness-corrected EFTEM image obtained with the energy window 2–4 eV. (c) The simulated thickness contrast. (d) The line scans of intensity profiles from the EFTEM images before and after thickness-correction (left panel) and the comparison along the two orthogonal directions after correction (right panel). (e) The anisotropic SP enhancement factors for various nanowires with intensity taken right at the interfaces and integrated out to various distances (up to 20 nm) from the interface. The diameter of selected Au/silica nanowires and the thickness of silica layer are indicated: (a) 99 nm/8 nm, (b) 132 nm/15 nm, (c) 78 nm/16 nm, and (d) 123 nm/20 nm.
Polarization-dependent photoresponse measurements. (a) The sketch of the experimental setup. (b) The photoinduced current response at room temperature for single gold/silica nanowire as a function of time due to the changes in switching (on/off) and polarization of incident laser (532 nm) illumination from perpendicular to parallel to the Au/silica nanowire.
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