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Nanoscale Res Lett ; 11(1): 327, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27405466


We propose a novel mirror-image nanoepsilon (MINE) structure to achieve highly localized and enhanced near field at its gap and systematically investigate its plasmonic behaviors. The MINE can be regarded as a combination of two fundamental plasmonic nanostructures: a nanorod dimer and nanoring. By adapting a nanoring surrounding a nanorod dimer structure, the nanorod is regarded as a bridge pulling the charges from the nanoring to the nanorod, which induces stronger plasmon coupling in the gap to boost local near-field enhancement. Two resonance peaks are identified as the symmetric and anti-symmetric modes according to the symmetries of the charge distributions on the ring and rod dimer in the MINE. The symmetric mode in the MINE structure is preferred because its charge distribution leads to stronger near-field enhancement with a concentrated distribution around the gap. In addition, we investigate the influence of geometry on the optical properties of MINE structures by performing experiments and simulations. These results indicate that the MINE possesses highly tunable optical properties and that significant near-field enhancement at the gap region and rod tips can be realized by the gap and lightning-rod effects. The results improve understanding of such complex systems, and it is expected to guide and facilitate the design of optimum MINE structures for various plasmonic applications.

Nanoscale Res Lett ; 10(1): 357, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26370132


Conductive ink using copper nanoparticles has attracted much attention in the printed electronics industry because of its low cost and high electrical conductivity. However, the problem of easy oxidation under heat and humidity conditions for copper material limits the wide applications. In this study, antioxidative copper inks were prepared by dispersing the nanoparticles in the solution, and then conductive copper films can be obtained after calcining the copper ink at 250 °C in nitrogen atmosphere for 30 min. A low sheet resistance of 47.6 mΩ/□ for the copper film was measured by using the four-point probe method. Importantly, we experimentally demonstrate that the electrical conductivity of copper films can be improved by increasing the calcination temperature. In addition, these highly conductive copper films can be placed in an atmospheric environment for more than 6 months without the oxidation phenomenon, which was verified by energy-dispersive X-ray spectroscopy (EDS). These observations strongly show that our conductive copper ink features high antioxidant properties and long-term stability and has a great potential for many printed electronics applications, such as flexible display systems, sensors, photovoltaic cells, and radio frequency identification.

Opt Express ; 21(12): 14090-6, 2013 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-23787599


We investigate both numerically and experimentally the optical properties and biosensing of gold elliptical nanoring (ENR) arrays with various aspect ratios. The gold ENR exhibits a strong localized surface plasmon bonding mode in near-infrared region, whose peak wavelength is red-shifted as increasing the aspect ratio under longitudinal and transverse polarizations. Furthermore, the disk- and hole-like optical properties for longitudinal and transverse modes are observed, which cause different behaviors in field intensity enhancement. For biomolecule sensing, we find that both modes show increased surface sensitivities when enlarging the aspect ratio of gold ENR.

Técnicas Biossensoriais/instrumentação , Ouro/química , Nanopartículas Metálicas/química , Nanotecnologia/instrumentação , Ressonância de Plasmônio de Superfície/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Ouro/efeitos da radiação , Nanopartículas Metálicas/efeitos da radiação
Nano Lett ; 12(3): 1648-54, 2012 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-22321005


We investigate the optical properties of gold nanoring (NR) dimers in both simulation and experiment. The resonance peak wavelength of gold NR dimers is strongly dependent on the polarization direction and gap distance. As the gold NR particles approach each other, exponential red shift and slight blue shift of coupled bonding (CB) mode in gold NR dimers for longitudinal and transverse polarizations are obtained. In finite element method analysis, a very strong surface plasmon coupling in the gap region of gold NR dimers is observed, whose field intensity at the gap distance of 10 nm is enhanced 23% compared to that for gold nanodisk (ND) dimers with the same diameter. In addition, plasmonic dimer system exhibits a great improvement in the sensing performance. Near-field coupling in gold NR dimers causes exponential increase in sensitivity to refractive index of surrounding medium with decreasing the gap distance. Compared with coupled dipole mode in gold ND dimers, CB mode in gold NR dimers shows higher index sensitivity. This better index sensing performance is resulted form the additional electric field in inside region of NR and the larger field enhancement in the gap region owing to the stronger coupling of collective dipole plasmon resonances for CB mode. These results pave the way to design plasmonic nanostructures for practical applications that require coupled metallic nanoparticles with enhanced electric fields.

Ouro/química , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Ressonância de Plasmônio de Superfície/métodos , Dimerização , Luz , Teste de Materiais , Tamanho da Partícula , Espalhamento de Radiação
Appl Phys Lett ; 98(15): 153108, 2011 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-21559087


We investigate the index sensing characteristics of plasmonic arrays based on square lattice slablike gold nanorings (NRs) with different ring widths. The gold NR arrays exhibit two extinction peaks in the visible and near-infrared corresponding to antibonding and bonding modes. Redshift and blueshift in antibonding and bonding modes when broadening the average ring width are observed. We experimentally demonstrate the sensitivity of bonding mode can be tuned by varying the average ring width. High sensitivity of 691 nm per refractive index unit is obtained for NRs with 199 nm average ring width.