Images illustrating the optical properties of metal nanoparticles and range of nanoparticle size. (a) Au, Ag, and Au/Ag alloy nanoparticles in solution. (b) TEM image of alloy nanoparticles indicating range of size from up to in diameter.
SPR and diffraction data of alloy nanoparticles and their pure metal equivalents. (a) UV-Vis absorption spectra of Au, Ag, and alloy nanoparticles. (b) XRD lines for (111) planes in A silver, B gold, and C Ag/Au 1:1 alloy. Points are actual data points, line is single Gaussian fit.
SPR mapping across a single alloy nanoparticle displaying pure Au characteristic. (a) Bright-field image of Au/Ag alloy nanoparticle diameter. (b) EEL SI of nanoparticle (displaying ZLP intensity) and spectra positions 1–4. (c) Extracted EEL spectra indicating SPR at 1.42 eV. (d) Corresponding intensity maps of 1.42 eV SPR. (e) Surface plasmon excitation energies for pure gold and silver nanoparticles of different particle diameter. The SPR from the alloy nanoparticle in (a) is indicated as well as that of a homogeneous alloy particle.
SPR mapping across a single alloy nanoparticle displaying characteristics of Au/Ag segregation. (a) Bright-field image of Au/Ag alloy nanoparticle diameter. (b) EEL SI of nanoparticle (displaying ZLP intensity) and extracted spectra positions 1–4. (c) extracted EEL spectra indicating SPRs at 1.31, 3.14 eV, and a bulk resonance at 3.77 eV. (d) Intensity maps of 1.31 and 3.14 eV SPR and 3.77 eV bulk resonance.
Low resolution contrast imaging and intensity profiling of multiple alloy nanoparticles. Color rendered HAADF image of Au/Ag alloy nanoparticles. (a) Similar sized nanoparticle with approximately equivalent image intensity. (b) High intensity nanoparticles caused by increase in thickness due to clustering (multiple/overlapping). (c) Isolated nanoparticle with higher relative intensity due to Z contrast d, intensity of different sized nanoparticles taken from multiple HAADF images.
intensity profiles and Hirsch filtered images of alloy nanoparticles. (a) HAADF image of two Au/Ag alloy nanoparticles diameter and inset bright-field image. (b) Corresponding nanoparticle intensity profile extracted along the line A-B. (c) Kirsch filtered HAADF image indicating an intense feature in one of the particles in the inset HAADF image.
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