Strong coupling effects in hybrid plexitonic systems

Trabajo presentado a la 3rd International Conference on Applications of Optics and Photonics, celebrado en Faro (Portugal) del 8 al 12 de mayo de 2017.We investigated the interactions between localized plasmons in gold nanorods and excitons in J-aggregates and were able to track an anticrossing behavior of the hybridized modes both in the extinction and in the photoluminescence spectra of this hybrid system. We identified the nonlinear optical behavior of this system by transient absorption spectroscopy. Finally using magnetic circular dichroism spectroscopy we showed that nonmagnetic organic molecules exhibit magneto-optical response due to binding to a plasmonic nanoparticles. In our experiments we also studied the effect of detuning as well as the effect of off- and on resonance excitation on the hybrid states.We acknowledge financial support from Project Fis2016.80174-P (PLASMOQUANTA) from MINECO (Ministerio de Economía y Competitividad). L.L.-M. acknowledges funding from the European Research Council (ERC Advanced Grant 267867, Plasmaquo). This study was supported by the Ministry of Education and Science of the Russian Federation, grant no. 14.Y26.31.0011.Peer Reviewe

Whispering gallery modes in photoluminescence and Raman spectra of a spherical microcavity with CdTe quantum dots: anti-Stokes emission and interference effects

We have studied the photoluminescence and Raman spectra of a system consisting of a polystyrene latex microsphere coated by CdTe colloidal quantum dots. The cavity-induced enhancement of the Raman scattering allows the observation of Raman spectra from only a monolayer of CdTe quantum dots. Periodic structure with very narrow peaks in the photoluminescence spectra of a single microsphere was detected both in the Stokes and anti-Stokes spectral regions, arising from the coupling between the emission of quantum dots and spherical cavity modes

CdTe Quantum Dot/Dye Hybrid System as Photosensitizer for Photodynamic Therapy

We have studied the photodynamic properties of novel CdTe quantum dots—methylene blue hybrid photosensitizer. Absorption spectroscopy, photoluminescence spectroscopy, and fluorescence lifetime imaging of this system reveal efficient charge transfer between nanocrystals and the methylene blue dye. Near-infrared photoluminescence measurements provide evidence for an increased efficiency of singlet oxygen production by the methylene blue dye. In vitro studies on the growth of HepG2 and HeLa cancerous cells were also performed, they point toward an improvement in the cell kill efficiency for the methylene blue-semiconductor nanocrystals hybrid system

Strong plasmon-exciton coupling in a hybrid system of gold nanostars and J-aggregates

This is an Open Access article distributed under the terms of the Creative Commons Attribution License.Hybrid materials formed by plasmonic nanostructures and J-aggregates provide a unique combination of highly localized and enhanced electromagnetic field in metal constituent with large oscillator strength and extremely narrow exciton band of the organic component. The coherent coupling of localized plasmons of the multispiked gold nanoparticles (nanostars) and excitons of JC1 dye J-aggregates results in a Rabi splitting reaching 260 meV. Importantly, broad absorption features of nanostars extending over a visible and near-infrared spectral range allowed us to demonstrate double Rabi splitting resulting from the simultaneous coherent coupling between plasmons of the nanostars and excitons of J-aggregates of two different cyanine dyes.This work was supported by the ETORTEK 2011–2013 project ‘nanoIKER’ from the Department of Industry of the Basque Government and by the Visiting Fellowship program of Ikerbasque Foundation.Peer Reviewe

Efficient energy transfer in hybrid organic/inorganic semiconductor nanostructures

Trabajo presentado al: "International Workshop Photonics of Functional Nanomaterials" celebrado en Hong Kong del 6 al 9 de Mayo de 2013.Highly luminescent semiconductor nanocrystals possess a number of interesting and important properties that are tunable thanks to their size-dependent discrete electronic spectra characteristic of quantum dots (QDs). In this work we studied the optical properties of a novel type of hybrid structures that combine CdTe QDs with organic dye molecules (Pseudocyanine iodide (PIC)) in a J-aggregate state. Due to the excitonic nature of electronic excitations, J-aggregates have the narrowest absorption and luminescence bands among organic materials, large oscillator strengths and giant third-order nonlinear susceptibility. It was found that aggregation of PIC molecules can be efficiently triggered by fast injection of solution of CdTe QDs into concentrated dye solution resulting in formation of hybrid nano-structures. In developed structures optical energy harvested by the quantum dots as artificial antennas then transferred to J-aggregates to enhance the photostability and efficiency of the carriers recombination. To fabricate CdTe/J-aggregates hybrid nanostructures we have used an approach based on electrostatic interaction between the positively charged dye and CdTe QDs capped with thioglycolic acid and, thus, carrying a negative charge. In order to develop an efficient hybrid material operating in the FRET regime, we carefully selected the PL colors (diameters) of the QD (donors of energy) to be optically coupled with absorption of J-aggregates. Also we took advantage of extremely thin surface ligand shell (~0.5 nm) of CdTe QDs, which insures high efficiency of energy transfer. Formed QD/J-aggregate FRET system shows the broadband absorption in the visible and the ultraviolet part of the spectrum typical of quantum dots, along with the narrow emission linewidths characteristic of J-band emitters (~15 nm full width at half-maximum). We use absorption and photoluminescence spectroscopy and photoluminescence lifetime studies to conclude that efficiency of energy transfer is 95%.Peer reviewe

Energy transfer in hybrid organic/inorganic semiconductor nanostructures

We report on direct formation of J-aggregates in cyanine dye solution by injection of colloidal CdTe quantum dots. The optical properties of formed J-aggregates have been investigated by absorption and photoluminescence spectroscopy and fluorescence lifetime imaging microscopy. Quantum dots/J-aggregate system shows the enhanced absorption in visible and ultraviolet parts of the spectrum typical of quantum dots, along with the narrow emission linewidth and fast recombination rate characteristic of the J-band emitters. Our studies suggest electrostatic association between the J-aggregates and quantum dots, followed by highly efficient energy transfer. Copyright © 2012 American Scientific Publishers All rights reserved.Peer Reviewe

Whispering gallery mode resonators with J-aggregates

We have studied the optical properties of a hybrid system consisting of cyanine dye J-aggregates attached to a spherical microcavity. A periodic structure of narrow peaks was observed in the photoluminescence spectrum of the J-aggregates, arising from the coupling between the emission of J-aggregates and the whispering gallery modes (WGMs) of the microcavity. The most striking result of our study is the observation of polarization sensitive mode damping caused by re-absorption of J-aggregate emission. This effect manifests itself in dominating emission from TM modes in the spectral region of J-aggregates absorption band where the TE modes are strongly suppressed. In contrast, the TE modes totally dominate emission spectrum in the region where absorption is negligible. We also demonstrate that the emission intensity can be further enhanced by depositing a hybrid layer of J-aggregates and Ag nanoparticles onto the spherical microcavity. Owing to the concerted action of WGMs and plasmonic hot spots in the Ag aggregates, we observe an enhanced Raman signal from the J-aggregates. Microcavities covered by J-aggregates and plasmonic nanoparticles could be thus useful for a variety of photonic applications in basic science and technology.Peer Reviewe

Coupling effect in hybrid system of plasmonic nanoparticles and J-aggregates yields double Rabi splitting

Trabajo presentado a la 16th International Conference on Transparent Optical Networks (ICTON), celebrada en Grazer Messe (Austria) del 6 al 10 de julio de 2014.In this paper, we discuss our recent results on development and characterization of three-component hybrid systems consisting of plasmonic nanostructures and two different organic dye molecules in a J-aggregate state. The measured absorption spectra exhibit a strongly suppressed absorption at wavelengths which correspond to the J-aggregate absorption bands, manifesting strong interaction between the localized surface plasmon of the plasmonic and excitonic systems. The observed dips in absorption spectra of hybrid systems correspond to an average vacuum Rabi splitting of the order of 200 meV. These findings could pave the way towards development of novel sensing devices using strong light-matter interaction on the nanoscale.Peer Reviewe

Hybrid organic/inorganic semiconductor nanostructures with highly efficient energy transfer

Using electro-static assembly of complementary organic (cyanine dye) and inorganic (quantum dots) building blocks we report on formation of an advanced nanohybrid system with highly efficient nonradiative energy transfer properties. In contrast to previous approaches, formation of J-aggregates in cyanine dye solution was triggered by direct injection of as-synthesized colloidal CdTe quantum dots without any additional surface treatment. The optical properties of formed hybrid aggregates have been investigated by absorption and photoluminescence spectroscopy and fluorescence lifetime imaging microscopy. A quantum dot/J-aggregate system shows the enhanced absorption in visible and ultraviolet parts of the spectrum typical of quantum dots, along with the narrow emission linewidth and fast recombination rate characteristic of the J-band emitters. These quantum dot/J-aggregate hybrid systems may have applications in light harvesting systems with the extended spectral absorption as well as optical sensors and optoelectronic devices. © The Royal Society of Chemistry 2012.This work was in part financially supported by Ikerbasque Visiting Fellowship (NG). DS and YR acknowledge the support received from the European Science Foundation (activity PLASMON - BIONANOSENSE).Peer Reviewe