Gold nanorods with aspect ratios of from 1 （particles） to 31.6 were synthesized by the seed-mediated method and packed in a highly ordered structure on a large scale on silicon substrates through capillary force ind...Gold nanorods with aspect ratios of from 1 （particles） to 31.6 were synthesized by the seed-mediated method and packed in a highly ordered structure on a large scale on silicon substrates through capillary force induced self-assembly behaviour during solvent evaporation. The gold nanorod surface exhibits a strong enhancing effect on Raman scattering spectroscopy. The enhancement of Raman scattering for two model molecules （2-naphthalenethiol and rhodamine 6C） is about 5-6 orders of magnitude. By changing the aspect ratio of the Au nanorods, we found that the enhancement factors decreased with the increase of aspect ratios. The observed Raman scattering enhancement is strong and should be ascribed to the surface plasmon coupling between closely packed nanorods, which may result in huge local electromagnetic field enhancements in those confined junctions.展开更多
A fabrication process based on the self-assembling polystyrene spheres is proposed to obtain hole arrayed metal-insulator-metal （HA-MIM） structure for surface enhanced Raman scattering （SERS）. The localized field ...A fabrication process based on the self-assembling polystyrene spheres is proposed to obtain hole arrayed metal-insulator-metal （HA-MIM） structure for surface enhanced Raman scattering （SERS）. The localized field enhancement aroused by the gap resonance in the HA-MIM structure is analyzed by finite-different time domain （FDTD） method. With reference to the theory result, the structure is experimentally fabricated and the Raman scattering spectrum of rhodamine 6G （R6G） is measured by a miniaturized Raman spectrometer. The results shows that the enhancement factor is 3.85 times higher than the control sample with single layered metal hole array. The fabrication process to obtain the HA-MIM SERS substrate is reproducible, fast, large area and low cost.展开更多
Creating nanoscale and sub-nanometer gaps between noble metal nanoparticles is critical for the applications of plasmonics and nanophotonics. To realize simultaneous attainments of both the op- tical spectrum and the ...Creating nanoscale and sub-nanometer gaps between noble metal nanoparticles is critical for the applications of plasmonics and nanophotonics. To realize simultaneous attainments of both the op- tical spectrum and the gap size, the ability to tune these nanoscale gaps at the sub-nanometer scale is particularly desirable. Many nanofabrication methodologies, including electron beam lithography, self-assembly, and focused ion beams, have been tested for creating nanoscale gaps that can de- liver significant field enhancement. Here, we survey recent progress in both the reliable creation of nanoscale gaps in nanoparticle arrays using self-assemblies and in the in-situ tuning techniques at the sub-nanometer scale. Precisely tunable gaps, as we expect, will be good candidates for future investigations of surface-enhanced Raman scattering, non-linear optics, and quantum plasmonics.展开更多
We reported sonication-mediated film assembly of gold nanoparticles at a water/hexane interface used as a surface-enhanced Raman scattering(SERS) substrate.Gold colloids/hexane biphasic system was emulsified by sonica...We reported sonication-mediated film assembly of gold nanoparticles at a water/hexane interface used as a surface-enhanced Raman scattering(SERS) substrate.Gold colloids/hexane biphasic system was emulsified by sonication,and then the emulsions were left undisturbed to allow natural breaking emulsions.In the end,gold nanoparticle films were formed at the interface.The interfacial nanoparticle films can be easily transferred onto a Cu grid and Si wafer for transmission electron microscopy(TEM) and SERS characterizations,respectively.TEM image shows that the as-formed gold nanoparticle films are of a monolayer structure without notable aggregates.SERS measurements indicate that when the gold nanoparticle films were used as SERS substrates to detect 4-MPY,the detection limit can be reached to 1×10-8 mol/L.展开更多
We reported on a simple and general interfacial self-assembly approach to fabricate plasmonic superlattice sheets in extremely large scale, which can be up to ca. 50 cm2, based on different types of noble metal nanopa...We reported on a simple and general interfacial self-assembly approach to fabricate plasmonic superlattice sheets in extremely large scale, which can be up to ca. 50 cm2, based on different types of noble metal nanoparticles. The self-assembled nanofilms exhibit exciting plasmonic properties with mirror-like reflectance, represented by vivid colour changes. More important, such superlattice sheets can be easily transferred and explored as highly efficient shape-dependent surface enhanced raman scattering（SERS） substrates, as well as flexible and recyclable shape-dependent substrate-supporting nanocatalysts sheets. The conversion of 4-NPH were kept as high as 95% after the nanocatalyst sheets were used for six cycles. The interfacial self-assembly method can be exploited for develop- ment of optical and nanocatalysts devices such as flexible colour filters, molecular sensors and flexible plasmonic nanofilms.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.50872147)the National High Technology Research and Development Program of China (Grant No.2007AA03Z305)the Special Doctoral Foundation of the Ministry of Education of China (Grant No.20775030)
文摘Gold nanorods with aspect ratios of from 1 （particles） to 31.6 were synthesized by the seed-mediated method and packed in a highly ordered structure on a large scale on silicon substrates through capillary force induced self-assembly behaviour during solvent evaporation. The gold nanorod surface exhibits a strong enhancing effect on Raman scattering spectroscopy. The enhancement of Raman scattering for two model molecules （2-naphthalenethiol and rhodamine 6C） is about 5-6 orders of magnitude. By changing the aspect ratio of the Au nanorods, we found that the enhancement factors decreased with the increase of aspect ratios. The observed Raman scattering enhancement is strong and should be ascribed to the surface plasmon coupling between closely packed nanorods, which may result in huge local electromagnetic field enhancements in those confined junctions.
文摘A fabrication process based on the self-assembling polystyrene spheres is proposed to obtain hole arrayed metal-insulator-metal （HA-MIM） structure for surface enhanced Raman scattering （SERS）. The localized field enhancement aroused by the gap resonance in the HA-MIM structure is analyzed by finite-different time domain （FDTD） method. With reference to the theory result, the structure is experimentally fabricated and the Raman scattering spectrum of rhodamine 6G （R6G） is measured by a miniaturized Raman spectrometer. The results shows that the enhancement factor is 3.85 times higher than the control sample with single layered metal hole array. The fabrication process to obtain the HA-MIM SERS substrate is reproducible, fast, large area and low cost.
文摘Creating nanoscale and sub-nanometer gaps between noble metal nanoparticles is critical for the applications of plasmonics and nanophotonics. To realize simultaneous attainments of both the op- tical spectrum and the gap size, the ability to tune these nanoscale gaps at the sub-nanometer scale is particularly desirable. Many nanofabrication methodologies, including electron beam lithography, self-assembly, and focused ion beams, have been tested for creating nanoscale gaps that can de- liver significant field enhancement. Here, we survey recent progress in both the reliable creation of nanoscale gaps in nanoparticle arrays using self-assemblies and in the in-situ tuning techniques at the sub-nanometer scale. Precisely tunable gaps, as we expect, will be good candidates for future investigations of surface-enhanced Raman scattering, non-linear optics, and quantum plasmonics.
文摘We reported sonication-mediated film assembly of gold nanoparticles at a water/hexane interface used as a surface-enhanced Raman scattering(SERS) substrate.Gold colloids/hexane biphasic system was emulsified by sonication,and then the emulsions were left undisturbed to allow natural breaking emulsions.In the end,gold nanoparticle films were formed at the interface.The interfacial nanoparticle films can be easily transferred onto a Cu grid and Si wafer for transmission electron microscopy(TEM) and SERS characterizations,respectively.TEM image shows that the as-formed gold nanoparticle films are of a monolayer structure without notable aggregates.SERS measurements indicate that when the gold nanoparticle films were used as SERS substrates to detect 4-MPY,the detection limit can be reached to 1×10-8 mol/L.
基金The National Natural Science Foundation of China(Nos.61275153,61320106014,and 11404177)the Natural Science Foundation of Zhejiang(No.LY12A04002)the International Collaboration Program of the Natural Science Foundation of Ningbo(Nos.2010D10018and 2012A610107)
基金Supported by the National Natural Science Foundation of China（No.51405112） and the China Postdoctoral Science l~＇ounda- tion（Nos.2015T80336, 2014M551229）.
文摘We reported on a simple and general interfacial self-assembly approach to fabricate plasmonic superlattice sheets in extremely large scale, which can be up to ca. 50 cm2, based on different types of noble metal nanoparticles. The self-assembled nanofilms exhibit exciting plasmonic properties with mirror-like reflectance, represented by vivid colour changes. More important, such superlattice sheets can be easily transferred and explored as highly efficient shape-dependent surface enhanced raman scattering（SERS） substrates, as well as flexible and recyclable shape-dependent substrate-supporting nanocatalysts sheets. The conversion of 4-NPH were kept as high as 95% after the nanocatalyst sheets were used for six cycles. The interfacial self-assembly method can be exploited for develop- ment of optical and nanocatalysts devices such as flexible colour filters, molecular sensors and flexible plasmonic nanofilms.
