Interstitial-Dependent Enhanced Photoluminescence: A Near-Field Microscopy on Single Spheroid to Dimer, Tetramer, and Few Particles Gold Nanoassembly

Mohammad Kamal Hossain*, Masahiro Kitajima, Kohei Imura, Hiromi Okamoto

*この研究の対応する著者

研究成果: Article査読

12 被引用数 (Scopus)

抄録

Interstitials to be active or inactive depend on the characteristics of nanoaggregate. In this perspective, near-field scanning optical microscopy has been utilized to probe well-defined monomer, dimer, tetramer, and small assembly of gold nanoparticles of 60 nm diameter with spatial resolution of â35 nm. Confinement of localized surface plasmon resonances (LSPRs)-mediated near electromagnetic (EM) field distribution was observed through two-photon induced photoluminescence (TPI-PL) since TPI-PL emission is proportional to the fourth power of induced EM-field. It was revealed that the intensity of TPI-PL observed in closely connected nanoparticles was very strong with reference to those obtained in the presence of isolated nanoparticles of the same size. Among the closely connected nanoparticles, interparticle gap and interparticle axes played a vital role in TPI-PL emission enhancement, as was evident and observed directly through TPI-PL intensity distribution. Correlated local geometry and emission distribution confirmed that interstitials along the active interparticle axes exhibits confined and enhanced TPI-PL emission. The emission intensity for dimers was found higher than that of tetramer of gold nanoparticles. In case of small assembly of the same gold nanoparticles, intensity was observed to be the highest of all along with wider full width at half-maximum of 188.09 nm, more than double of those obtained at dimers and tetramer. The observations were further demonstrated as a function of EM near-field distribution, as it is well-known that TPI-PL emission is enhanced by LSPRs-assisted EM-field localization. Model systems were designed along with geometries and parameters very similar to those under investigation. Finite-difference time-domain analysis was carried out to deduce near EM-field distributions at various deterministic factors such as size, interparticle gap, incident polarization, etc. A plausible explanation of enhanced and confined TPI-PL emissions in archetype interstitials of well-known plasmonic systems was highlighted.

本文言語English
ページ(範囲)2344-2354
ページ数11
ジャーナルJournal of Physical Chemistry C
121
4
DOI
出版ステータスPublished - 2017 2月 2

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • エネルギー(全般)
  • 物理化学および理論化学
  • 表面、皮膜および薄膜

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