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説明:

Wet-chemistry-synthesized gold nanourchins (Au NUs), characterized by spiky morphologies with spherical cores, exhibit complex and geometry-dependent plasmonic field enhancement properties distinct from those of symmetrical nanostructures. While plasmon hybridization and mode coupling in branched nanostructures have been broadly studied, the specific optical behavior of Au NUs─particularly regarding spike length distribution and ultrafast dynamics─remains underexplored. This study investigates the steady-state and transient absorption spectra of Au NUs with 50–80 nm cores and 5–20 nm spikes, revealing multiple resonance bands. Transient absorption spectroscopy at various excitation wavelengths confirmed the presence of distinct resonances. Electromagnetic simulations based on TEM tomography-inspired models identified two key extinction bands: a green-wavelength dark mode resonance and a red/nIR spike-induced resonance attributed to the lightning rod effect. Simulations further showed that short, uniformly distributed spikes (aspect ratio ≤1) weakly excite dark resonances, while longer spikes (aspect ratio >1) induce hybridized longitudinal resonances and significant redshifts. Broad spike length distributions result in multiple coexisting resonances, aligning with experimental extinction spectra. A preliminary surface-enhanced Raman scattering study using 2-naphthalene thiol confirmed stronger enhancement for long-spiked Au NUs under 785 nm excitation, validating the field enhancement potential of the identified resonances.

権利情報:

• In Copyright
  

  This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Nano Materials, copyright © 2025 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acsanm.5c03297.

キーワード: Plasmonics, Surface enhanced Raman spectroscopy, Nanoparticle

刊行年月日: 2025-10-10

出版者: American Chemical Society (ACS)

掲載誌:

• ACS Applied Nano Materials (ISSN: 25740970) vol. 8 issue. 40 p. 19322-19332

研究助成金:

• Lietuvos Mokslo Taryba MERANET-222

原稿種別: 著者最終稿 (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.6118

公開URL: https://doi.org/10.1021/acsanm.5c03297

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更新時刻: 2026-04-30 12:01:11 +0900

MDRでの公開時刻: 2026-09-29 08:46:31 +0900