Vicinity Of Silver Nanoparticles Research Articles

Enhanced emission of Nile Red on plasmonic platforms

Strongly enhanced fluorescence of Nile Red deposited in the vicinity of silver nanoparticles and gold semitransparent mirror was observed. The properties of three different plasmonic platforms based on TiO2, TiO2-GLYMO (1:1) and SiO2 matrices were studied with spectroscopic and microscopic techniques. Significant differences of Nile Red spectroscopic properties in both matrices were observed. In particular, the sensitivity of Nile Red fluorescence enhancement and its peak location to the polarity of local surrounding was found.

Luminescence of CdSe quantum dots near a layer of silver nanoparticles ion-synthesized in sapphire

We study the characteristics of the luminescence of composite films based on polymethyl methacrylate with CdSe quantum dots deposited from solution onto the surface of a sapphire substrate containing a preliminarily formed layer with ion-synthesized silver nanoparticles. The sapphire layer with silver nanoparticles exhibits selective plasmon absorption in the visible spectral range with a peak at 463 nm. Enhancement in the exciton luminescence intensity of quantum dots with a peak at 590 nm is observed upon excitation at wavelengths lying in the region of plasmon resonance of metal nanoparticles, as well as luminescence quenching for quantum dots located in the vicinity of silver nanoparticles.

Enhanced photochemistry of ethyl chloride on Ag nanoparticles.

Enhanced photodecomposition of ethyl chloride (EC) adsorbed on SiO2/Si (100) supported silver nanoparticles (Ag NPs) under ultrahigh vacuum (UHV) conditions has been studied in order to assess the potential contribution of plasmonic effects. The cross section for photodecomposition of EC and overall photoyield were found to increase with increasing photon energy regardless of the plasmon resonant wavelength and with Ag coverage without any noticeable particle size effect. The influence of EC-Ag NPs separation distance on the rate of EC decomposition was studied in order to examine potential local electric field influence on the photodissociation process. Long (∼5 nm) photoactivity decay distance has been observed which excludes local surface plasmon dominance in the photodecomposition event. These findings suggest that the alignment of excited electron energy and adsorbate affinity levels is central for efficient photochemical reactions, whereas short-range electric field enhancement by plasmon excitation on top and at the immediate vicinity of silver nanoparticles does not have any measurable effect.

Effect of Silver Nanoparticles on the Photoluminescence of Silicon Nanocrystals

ABSTRACT In this article, we report the photoluminescence of three different systems produced by ion implantation: a high-purity silica substrate with silicon nanocrystals and two samples containing silicon nanocrystals in the vicinity of silver nanoparticles. The silicon nanocrystals were formed inside silica matrix by 1.5MeV implantation of silicon ions and annealing. Subsequent implantations with silver ions at different energies were performed to vary the distance between the previously formed silicon nanocrystals and newly aggregated silver nanoparticles. The samples were studied by photoluminescence, Rutherford backscattering spectrometry, m-line, and optical absorption. The enhancement of photoluminescence is well evidenced at the lowest implantation energy of silver, but at higher energies, a decrease in intensity is observed.

Efficient infrared-to-visible upconversion emission in Nd3+-doped PbO-TeO2 glass containing silver nanoparticles

The effect of silver nanoparticles (NPs) on the optical properties of Nd3+-doped sodium-lead tellurite glass prepared by melting-quenching technique is investigated. The X-ray diffraction patterns confirm the amorphous nature of the samples. The average size of silver NPs increases from 7 to 18 nm by addition of AgNO3 content. The surface plasmon resonance band of the silver NPs was recorded at 522 nm for 0.5 mol. % AgNO3. Large upconversion enhancements (∼16 and 10 times) are attributed to the enlarged local field in vicinity of silver NPs. Feasible interactions between the excitation light and Nd3+:Ag NP co-doped tellurite glass are discussed.

Enhanced Infrared to Visible Upconversion Emission in Er<sup>3+</sup> Doped Phosphate Glass Containing Silver Nanoparticles

Phosphate glasses containing fixed concentration of rare-earth with and without metallic nanoparticles (NPs) having compositions (59.5-x) P2O5-MgO-xAgCl-0.5Er2O3, where 0 ≤ x ≤ 1.5 mol% was prepared using melt-quenching technique. Spectral characterizations were made using UV-VIS-IR spectroscopy and photoluminescence spectroscopy. Addition of silver NPs enhanced the corresponding absorption and was optimum at 1.5 mol% AgCl. Infrared to visible frequency upconversion (UC) emission were observed in the glass on pumping with 797 nm radiation. Furthermore, it was found that the emission at 540 nm, due to Er3+transition (4S3/2-4I15/2) was much more influenced by the silver NPs in comparison to the emission at 632 nm (4F9/2 - 4I15/2). These enhancements were attributed to the local fields present in the vicinity of silver NPs. Moreover, the rapid increase in the intensity of the green band as compared to the red band was due to the charge cloud effect of the plasmon band. Since green band lie more close to the plasmon frequency band of Ag and hence showed rapid increase compared to the far lying red bands. Our findings may contribute towards the development of solid state laser and sensors

Photon statistics in enhanced fluorescence from a single CdSe/ZnS quantum dot in the vicinity of silver nanoparticles

Single-photon emission behavior in the enhanced fluorescence from single colloidal quantum dots (QDs) near silver nanoparticles (AgNPs) was investigated using a single molecule fluorescence spectroscopy technique. It was found that the degree of fluorescence enhancement from single QDs with AgNPs increased with decrease in the lifetime and the probability of single-photon emission, that is, highly enhanced fluorescence with a shortened lifetime exhibited a low probability of single-photon emission. The present results yield new insights into fundamentals of QD-metal nanostructure interactions, and are also important to understand the mechanism of the fluorescence enhancement by localized surface plasmon of metal nanostructures.

Coherent random lasers in weakly scattering polymer films containing silver nanoparticles

We report on the observations of coherent random lasers in weakly scattering polymer films embedded with silver nanoparticles. The dominant oscillation cavity calculated from the ensemble-averaged power Fourier transform spectrum of single-shot emission spectra is shorter by more than two orders of magnitude than the scattering mean-free path, indicating that the oscillation cavity is loosely associated with multiple scattering. We suggest that the coherent feedback arises from the cooperative effect of light scattering and field enhancement in the vicinity of silver nanoparticles.

The phase-response effect of size-dependent optical enhancement in a single nanoparticle

We demonstrate detailed simulations and experiments of near-field phase-response in a single silver nanoparticle. The plasmon-photon interaction is directly observed in the vicinity of silver nanoparticles through a near-field scanning optical microscope (NSOM). Our results manifest the correlation of phase-response and size-dependent optical enhancement. Detailed interference behaviors between optical excitation and plasmon mediated re-radiation are revealed on a single particle basis. This observation facilitates nano-applications in controlling the spatial distribution of surface plasmon (SP) modes by means of nanostructures.