ABSTRACT
We investigate the optical response of a gold nanorod array coupled with a semicontinuous nanoparticle film. We find that, as the gold nanoparticle film is adjusted to the percolating regime, the nanorod-film hybrids are tuned into plasmonic Fano resonance, characterized by the coherent coupling of discrete plasmonic modes of the nanorod array with the continuum band of the percolating film. Consequently, optical transmission of the percolating film is substantially enhanced. Even more strikingly, electromagnetic fields around the nanorod array become much stronger, as reflected by 2 orders of magnitude enhancement in the avalanche multiphoton luminescence. These findings may prove instrumental in the design of various plasmonic nanodevices.
ABSTRACT
Efficient plasmon-mediated excitation energy transfer between the CdSe/ZnS semiconductor quantum dots (QDs) across the silver nanowire array up to 560 nm in length is observed. The subwavelength imaging and spectral response of the silver nanowire arrays with near-field point-source excitations are revealed by theoretical simulations. Our studies demonstrate three advantages of the nanosystem: efficient exciton-plasmon conversion at the input side of the array through near-field strong coupling, directional waveguidance and resonant transmission via half-wave plasmon modes of the nanowire array, and subwavelength imaging at the output side of the array. These advantages allow a long-range radiative excitation energy transfer with a high efficiency and a good directionality.
Subject(s)
Energy Transfer , Nanotechnology/instrumentation , Nanowires/chemistry , Silver/chemistry , Absorption , Cadmium Compounds/chemistry , Quantum Dots , Selenium Compounds/chemistry , Semiconductors , Sulfides/chemistry , Zinc Compounds/chemistryABSTRACT
We experimentally demonstrated plasmon-assisted energy transfer (ET) between CdSe semiconductor quantum dots (QDs) self-assembled in a monolayer by using time-resolved micro-photoluminescence (PL) technique. The enhancements of PL intensity and ET efficiency were manipulated by adjusting thickness (Delta) of SiO(2) coating on large Ag nanoparticles. The PL enhancement factor of the acceptor QDs and the PL intensity ratio of acceptor-to-donor reached their maxima approximately 47 and approximately 14 when Delta = 7 nm, the corresponding ET efficiency reached 86%. We also presented theoretical analysis based on the rate equation. The theoretical calculations agreed with experimental data and revealed interesting physics of multipole effect, and metal nanoparticle induced quench effect and plasmon-enhanced Förster ET.
Subject(s)
Optics and Photonics , Quantum Dots , Semiconductors , Energy Transfer , Fluorescence Resonance Energy Transfer/methods , Light , Luminescence , Metal Nanoparticles/chemistry , Microscopy, Electron, Transmission/methods , Models, Theoretical , Nanotechnology/methods , Physics/methods , Spectrophotometry/methodsABSTRACT
We propose the effective dielectric function theory of metal granular composites modified with the metal particle size. The modified theory is used to explain the electrical conductivity, resonant plasmon absorption, and large nonlinear absorption of Au-TiO2 granular composite films with high-density metallic particles and a high electric percolation threshold. It is revealed that the decreasing metal particle size leads to an increasing percolation threshold and large enhancement of optical nonlinearity of the composites.
ABSTRACT
We used CdSe/ZnS quantum dots-ssDNA-fluorescent dye conjugates as bioprobes to detect micrococcal nuclease with high specificity and sensitivity, and further utilized the bioprobe to monitor the micrococcal nuclease activity in the culture medium of Staphylococcus aureus by fluorescence microscopy.
Subject(s)
Biosensing Techniques , Fluorescence Resonance Energy Transfer/methods , Micrococcal Nuclease/analysis , Quantum Dots , Cadmium Compounds/chemical synthesis , Cadmium Compounds/chemistry , Micrococcal Nuclease/metabolism , Nanotechnology , Rhodamines/chemistry , Spectrometry, Fluorescence , Staphylococcus aureus/chemistry , Zinc Compounds/chemistryABSTRACT
We first time prepared Nd(3+) ions doped anodic aluminum oxide (Nd:AAO) templates, reported linear, sublinear and superlinear photoluminescence (PL) from Nd:AAO templates loaded with Ag nanowires in different excitation power regions, in which, the excitation laser with wavelength 805 nm resonantly pumped the population to (4)F5/2 states of Nd(3+), and the radiative transitions (4)F(3/2) -->(4)I(9/2) of Nd(3+) centered at 880 nm. The excitation power dependences of emission polarization ratio and the spectral width were also investigated. The observed nonlinear amplifications of the PL intensity implied strong interaction between randomly-dispersed Nd(3+) ions and ordered-arrayed Ag nanowires in AAO templates.
