Single InGaAs Quantum Dot Coupling to the Plasmon Resonance of a Metal Nanocrystal

We report the observation of coupling of single InGaAs quantum dots with the surface plasmon resonance of a metal nanocrystal, which leads to clear enhancement of the photoluminescence in the spectral region of the surface plasmon resonance of the metal structures. Sharp emission lines, typical for single quantum dot emission, are observed, whereas for reference samples, only weak continuous background emission is visible. The composite metal–semiconductor structure is prepared by molecular beam epitaxy utilizing the principle of strain-driven adatom migration for the positioning of the metal nanocrystals with respect to the quantum dots without use of any additional processing steps

Transition from localized surface plasmon resonance to extended surface plasmon-polariton as metallic nanoparticles merge to form a periodic hole array

W. Andrew Murray, Simion Astilean, and William L. Barnes, Physical Review B, Vol. 69, article 165407 (2004). "Copyright © 2004 by the American Physical Society."We present results of experiments to determine the dispersion of the plasmon modes associated with periodic silver nanoparticle and nanohole arrays fabricated using an extension of the nanosphere lithography technique. Ordered monolayers of polystyrene nanospheres were used as a deposition mask through which silver was deposited by thermal evaporation, subsequent removal of the nanospheres thus leaving an array of metallic nanoparticles. By reactive-ion etching of the nanospheres in an oxygen plasma prior to silver deposition, arrays consisting of particles of increasing size were fabricated. The extremities of the particles eventually merge to create a continuous metallic network perforated by subwavelength holes, thus allowing a study of the particle-hole transition. Combining optical measurements of transmittance and reflectance with information gained using scanning electron microscopy, three separate regimes were observed. For low etch times the samples comprise mainly individual nanoparticles and the optical response is dominated by localized surface plasmon resonances that show no dispersion. As the etch time is increased almost all of the nanoparticles merge with adjacent particles, although many defects are present—notably where some particles fail to merge, a small gap being left between them. The presence of these defects prevents an abrupt structural transition from metallic nanoparticles to a continuous metallic film perforated by an array of nanoholes. The presence of such gaps also results in dispersion data that lack clearly defined features. A further increase in etch time leads to samples with no gaps: instead, a continuous metal film perforated by a nanohole array is produced. The optical response of these structures is dominated by extended surface plasmon-polariton modes

ФОРМИРОВАНИЕ НАНОСТЕРЖНЕЙ ЗОЛОТА И ПЛЕНОК НА ИХ ОСНОВЕ ДЛЯ ПРИМЕНЕНИЯ В СПЕКТРОСКОПИИ ГИГАНТСКОГО КОМБИНАЦИОННОГО РАССЕЯНИЯ СВЕТА

The formation of gold nanorods as well as thin films prepared via electrostatic deposition of gold nanorods has been investigated. The obtained gold nanorods films have been used as substrates for the surface-enhanced Raman scattering analysis of sulfur-free organic molecules mitoxantrone and malachite green as well as inorganic malachite microcrystals for the first time. The additional modification of films with L-cysteine allows one to significantly extend the use of gold nanorods for the surface-enhanced Raman scattering analysis.Исследовано формирование наностержней золота и тонких пленок на их основе, приготовленных методом электростатического осаждения. Впервые на наностержнях золота получены спектры гигантского комбинационного рассеяния неорганических микрокристаллов малахита, а также органических несеросодержащих молекул митоксантрона и малахитового зеленого. Дополнительная процедура модификации данных пленок L-цистеином позволяет существенно расширить возможности использования наностержней золота для гигантского комбинационного рассеяния широкого ряда соединений

Управление фотостабильностью полупроводниковых квантовых точек с помощью наночастиц золота

The effect of plasmonic films containing gold nanoparticles of different shape (nanospheres and nanorods) on the photostability of InP/ZnSe/ZnSeS/ZnS and CdSe/ZnCdS/ZnS quantum dots with core/shell structure has been determined. Gold nanospheres increase the photostability of InP/ZnSe/ZnSeS/ZnS quantum dots when excited by blue LED radiation when reducing the average lifetime of the excited state of quantum dots and, accordingly, when reducing the probability of Auger processes. An increase in the average lifetime of the excited state of CdSe/ZnCdS/ZnS quantum dots in complexes with gold nanorods leads to a decrease in the photostability upon excitation at 449 and 532 nm.Установлено влияние наночастиц золота различной формы (наносферы и наностержни) на фотостабильность квантовых точек InP/ZnSe/ZnSeS/ZnS и CdSe/ZnCdS/ZnS со структурой типа «ядро/оболочка». Наносферы золота повышают фотостабильность квантовых точек InP/ZnSe/ZnSeS/ZnS при возбуждении излучением синего диапазона за счет уменьшения среднего времени жизни возбужденного состояния квантовых точек и, соответственно, снижения вероятности Оже-процессов. Увеличение среднего времени жизни возбужденного состояния квантовых точек CdSe/ZnCdS/ZnS в комплексах с наностержнями золота приводит к снижению фотостабильности при возбуждении на 449 и 532 нм

Nanoscale control of Ag nanostructures for plasmonic fluorescence enhancement of near-infrared dyes

Potential utilization of proteins for early detection and diagnosis of various diseases has drawn considerable interest in the development of protein-based detection techniques. Metal induced fluorescence enhancement offers the possibility of increasing the sensitivity of protein detection in clinical applications. We report the use of tunable plasmonic silver nanostructures for the fluorescence enhancement of a near-infrared (NIR) dye (Alexa Fluor 790). Extensive fluorescence enhancement of ∼2 orders of magnitude is obtained by the nanoscale control of the Ag nanostructure dimensions and interparticle distance. These Ag nanostructures also enhanced fluorescence from a dye with very high quantum yield (7.8 fold for Alexa Fluor 488, quantum efficiency (Qy) = 0.92). A combination of greatly enhanced excitation and an increased radiative decay rate, leading to an associated enhancement of the quantum efficiency leads to the large enhancement. These results show the potential of Ag nanostructures as metal induced fluorescence enhancement (MIFE) substrates for dyes in the NIR “biological window” as well as the visible region. Ag nanostructured arrays fabricated by colloidal lithography thus show great potential for NIR dye-based biosensing applications

Plasmonic enhancement of luminescence efficiency in light emitting structures

There are successful evidences of plasmonic nanoparticle utility for QLEDs efficiency for both photo- and electroluminescence. The potentially promising plasmonic ehnancement of LED performance consists in: photo- and electroluminescence intensity enhancement; decay rate enhancement, modulation rate enhancement; luminophore photostability enhancement; improving light directionalities and light polarization of LEDs

Emission enhancement of semiconductor nanocrystals by gold nanorods: a recipe

In this work, we experimentally and theoretically investigated conditions of the emission enhancement of semiconductor nanocrystals (on the example of CdSe-based quantum dots, QDs) by GNRs