Camposeo Andrea, Jurga Radoslaw, Moffa Maria, Portone Alberto, Cardarelli Francesco, Della Sala Fabio, Ciracì Cristian, Pisignano Dario
NEST, Istituto Nanoscienze-CNR, Piazza San Silvestro 12, I-56127, Pisa, Italy.
Center for Biomolecular Nanotechnologies@UNILE, Istituto Italiano di Tecnologia, Via Barsanti 14, I-73010, Arnesano, Italy.
Small. 2018 May;14(19):e1800187. doi: 10.1002/smll.201800187. Epub 2018 Apr 14.
Hybrid polymer-plasmonic nanostructures might combine high enhancement of localized fields from metal nanoparticles with light confinement and long-range transport in subwavelength dielectric structures. Here, the complex behavior of fluorophores coupling to Au nanoparticles within polymer nanowires, which features localized metal-enhanced fluorescence (MEF) with unique characteristics compared to conventional structures, is reported. The intensification effect when the particle is placed in the organic filaments is remarkably higher with respect to thin films of comparable thickness, thus highlighting a specific, nanowire-related enhancement of MEF effects. A dependence on the confinement volume in the dielectric nanowire is also indicated, with MEF significantly increasing upon reduction of the wire diameter. These findings are rationalized by finite element simulations, predicting a position-dependent enhancement of the quantum yield of fluorophores embedded in the fibers. Calculation of the ensemble-averaged fluorescence enhancement unveils the possibility of strongly enhancing the overall emission intensity for structures with size twice the diameter of the embedded metal particles. These new, hybrid fluorescent systems with localized enhanced emission, and the general nanowire-enhanced MEF effects associated to them, are highly relevant for developing nanoscale light-emitting devices with high efficiency and intercoupled through nanofiber networks, highly sensitive optical sensors, and novel laser architectures.
混合聚合物-等离子体纳米结构可能会将金属纳米颗粒产生的局域场的高度增强与亚波长介电结构中的光限制和长程传输结合起来。在此，报道了荧光团与聚合物纳米线内的金纳米颗粒耦合的复杂行为，其具有与传统结构相比具有独特特性的局域金属增强荧光（MEF）。与具有可比厚度的薄膜相比，当颗粒置于有机细丝中时的增强效应明显更高，从而突出了与纳米线相关的MEF效应的特定增强。还表明了对介电纳米线中限制体积的依赖性，随着线径减小，MEF显著增加。这些发现通过有限元模拟得到了合理的解释，该模拟预测了嵌入纤维中的荧光团量子产率的位置依赖性增强。对总体平均荧光增强的计算揭示了对于尺寸为嵌入金属颗粒直径两倍的结构，有强烈增强整体发射强度的可能性。这些具有局域增强发射的新型混合荧光系统，以及与之相关的一般纳米线增强的MEF效应，对于开发通过纳米纤维网络高效且相互耦合的纳米级发光器件、高灵敏度光学传感器和新型激光架构具有高度相关性。
