A comparative study of classical approaches to surface plasmon resonance of colloidal gold nanorods

Abstract

We report the errors in the evaluation of the surface plasmon resonance of gold nanorods by three classical approaches: the Gans model, the Discrete Dipole Approximation and the Surface Integral method. Using these methods, which are based on the propagation of an electromagnetic wave through a composite medium with different refractive indices, might result in an inaccurate prediction of absorption maxima. For test samples of nanorods prepared by a seed-mediated method, whose homogeneity and quality were also fully demonstrated in this study, the mismatches in the wavelengths of absorption maxima Δλ max j j between experimental and theoretical data were observed to be greater than 50 nm. In general, the observed surface plasmon resonances exhibit two distinctive bands corresponding to the transverse and longitudinal modes. The weak transverse mode was located in the region from 510 to 518 nm and varied slightly with the aspect ratio of the rods. In contrast, the longitudinal mode showed a strong dependence on aspect ratio and ranged from 658 to 768 nm. We demonstrated that the mismatches may be sufficiently reduced if the interdependence between these two modes is taken into account.

Synthesis and Optical Properties of Cu2O and Au-Cu2O core-shell particles

“…As shown in Fig.2.b., the synthesized Au nanoparticles seem to be quasi-spherical in shape and their average size was estimated to be 16.8 ± 1.9 nm. The UV_Vis spectrum of the synthesized Au nanoparticles exhibits only one absorption peak at about 520 nm corresponding to the dipole Surface Plasmon Resonance (SPR) of the symmetric spherical gold nanoparticles [9]. The morphology of the synthesized Au-Cu 2 O core-shell nanoparticles was examined using the FESEM and TEM images.…”

“…The actual shape of Au nanoparticles has a strong influence on shaping the morphology of the Cu 2 O shell [10]. Although the Au nanoparticles appeared as quasi-spherical particles, they are best described as multifacetedtruncated particles [9]. Due to the similar crystal structure and relatively small lattice mismatch (111) and (200) diffraction peaks of the fcc phase of metallic gold structure (PDF 04-0784, ICDD).…”

“…The synthesis procedure of the gold nanoparticles was reported in detail elsewhere [9]. Cu 2 O and Au-Cu 2 O core-shell nanoparticles were fabricated using the technique reported in [10][11][12][13].…”

Structure and Electrical Properties of the Thin Gold Leaves Fabricated by Vietnam Traditional Laminating Technology

“…There are 2 absorption maxima as seen, where one falls in the ultraviolet region, the other appears in the visible region. The maximum has a wavelength of 470nm, that is in the green range, differs from that of the pure bulk gold [9] and the gold nanoparticles [6,8]. For the optical properties of the leaves we measured the absorption spectra in the range of the wavelength from 200 to 800 nm (Fig.…”

“…The gold resistivity at room temperature is about 2.27 × 10 −8 Ω.m [1]. While the bulk gold consists of the particles of µm size, showing the yellow surface color, the gold colloids usually exhibit a much smaller average size of the particles (5 -50 nm), thus, transmitting a color varying from light red (700 nm) to dark blue (400 nm) according to the existance of the palsmon resonances at thr surfaces of the nanoparticles [2,6,7]. As known, the photoluminescence of a solid gold has a peak around 540nm, this peak shifts to the higher frequency in the low temperature [3].…”