Quantitative Study of Plasmonic Gold Nanostar Geometry Toward Optimal SERS Detection

TY - JOUR

T1 - Quantitative Study of Plasmonic Gold Nanostar Geometry Toward Optimal SERS Detection

AU - Chung, Taerin

AU - Lee, Sang Hyuk

N1 - Funding Information: T.C. and S.-H.L. are supported by a grant from US Department of Energy (DE-SC0019313 to S.-H.L.). S.-H.L. is also supported by Rutgers New Faculty Startup Funds. Publisher Copyright: © 2022, The Author(s).

PY - 2022/10

Y1 - 2022/10

N2 - Complex shapes of gold nanostars (GNS) have been the major obstacle to the comprehensive understanding of the rich plasmonic phenomena of GNS. We conducted extensive, systematic numerical study of far-field and near-field spectral responses of GNS for varying geometrical parameters (e.g., number of spikes, spike tip angle, and spike-to-core ratio) to elucidate the relationship between the optical property and the geometry of GNS. We found that symmetric configurations of GNS spikes generated both dipole and quadrupole localized surface plasmon (LSP) modes, their hybridization resulted in the final near-field intensity at the spike tips, and there existed a specific GNS geometry that optimized the hybridization and thus the E-field intensity for any given wavelength. From these results, we further identified the shapes of GNS that generated the strongest Surface Enhanced Raman Scattering (SERS) enhancement factors in the visible and NIR spectral range. Hence, our results provide guiding principles in determining the optimal geometry of GNS for SERS applications with any choice of excitation wavelength.

AB - Complex shapes of gold nanostars (GNS) have been the major obstacle to the comprehensive understanding of the rich plasmonic phenomena of GNS. We conducted extensive, systematic numerical study of far-field and near-field spectral responses of GNS for varying geometrical parameters (e.g., number of spikes, spike tip angle, and spike-to-core ratio) to elucidate the relationship between the optical property and the geometry of GNS. We found that symmetric configurations of GNS spikes generated both dipole and quadrupole localized surface plasmon (LSP) modes, their hybridization resulted in the final near-field intensity at the spike tips, and there existed a specific GNS geometry that optimized the hybridization and thus the E-field intensity for any given wavelength. From these results, we further identified the shapes of GNS that generated the strongest Surface Enhanced Raman Scattering (SERS) enhancement factors in the visible and NIR spectral range. Hence, our results provide guiding principles in determining the optimal geometry of GNS for SERS applications with any choice of excitation wavelength.

KW - FDTD

KW - Gold nanostars

KW - LSPR

KW - Plasmon hybridization

KW - Plasmonic hotspots

KW - SERS

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U2 - https://doi.org/10.1007/s11468-022-01698-5

DO - https://doi.org/10.1007/s11468-022-01698-5

M3 - Article

SN - 1557-1955

VL - 17

SP - 2113

EP - 2121

JO - Plasmonics

JF - Plasmonics

IS - 5

ER -