Gabriele Raino`,†,* Thilo Sto¨ferle,† Chanhee Park,‡ Ho-Cheol Kim,‡,* Teya Topuria,‡ Philip M. Rice,‡ In-Joo Chin,§ Robert D. Miller,‡ and Rainer F. Mahrt†,*
Plasmonic Nanohybrid with Ultrasmall Ag Nanoparticles and Fluorescent Dyes †
IBM Research;Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland, ‡IBM Research;Almaden, 650 Harry Road, San Jose, California 95120-6099, United States, and §Polymer Science and Engineering Department, Inha University, 253 Yonghyun-dong, Incheon 402-751, Korea
arnessing surface plasmons is a promising route to reduce the dimensions of optical probes and devices deep into the subwavelength domain.1 Beyond this paramount scaling advantage, engineering plasmonexciton interaction opens up attractive ways to tailor the electro-optical properties of nanocomposites containing organic and/or inorganic emitters and metal nanocrystals. Previous studies mostly investigated hybrids with nanoparticle sizes (in diameter) between 10 and 100 nm211 owing to the large magnitude of the plasmonic eﬀect and small aﬃnity to aggregation. Only few eﬀorts cover ultrasmall nanocrystals,1216 although these are better suited for many applications, for example, in biology, where a minimal invasive integration is required,1216 as well as in catalysis,17,18 nanoimaging,19,20 sensing,21,22 and lithographic tools.23,24 We focus on the plasmonexciton interaction occurring among ultrasmall (23 nm) silver nanocrystals and ﬂuorescent dyes embedded in micelle structures. Thereby we are able to access the intriguing regime in which the dimensions of the nanoparticles and the characteristic energy transfer distance between the dyes are comparable. Metal nanoparticles (MNPs) which support a plasmonic resonance in the visible wavelength range are able to alter the absorption and emission properties of an emitter (ﬂuorescent dye) in close proximity to them.211,13,15,25 The metalemitter interaction can manifest itself by an enhancement or a quenching of the photoluminescence depending on the relative distance between the dye molecule and the metal. It was theoretically predicted26,27 and later experimentally demonstrated28,29 that the presence of metal nanoparticles can alter the Förster resonance energy transfer (FRET) mediated by the resonant dipoledipole interaction between two molecules in close RAINÒ ET AL.
ABSTRACT We investigate a hybrid nanocomposite combining ﬂuorescent dyes and ultrasmall