In the solution containing ammonia,silver nitrate was reduced by tartaric acid,and nano-silver colloids were generated.The products were characterized by transmission electron microscope(TEM) and X-ray diffraction(XRD...In the solution containing ammonia,silver nitrate was reduced by tartaric acid,and nano-silver colloids were generated.The products were characterized by transmission electron microscope(TEM) and X-ray diffraction(XRD).The results show that the average size of silver colloid particles is 25-30 nm and the shape is near-spherical.Researches on the character of resonance light scattering(RLS) of nano-silver colloid indicates that the strongest RLS peak of nano-silver colloid appeares at 447 nm.When BSA adding into the nano-silver colloid solution,the RLS peaks intensity was quenched.Based on this,a novel and simple method of determination of BSA was developed.Under optimum conditions,the linear response is over the range of 2.5pg/mL～2.5×106 pg/mL.展开更多
The authors have prepared suprameolecular systems of chiral Schiffbase ZnAZSB （Zn（II） complexes with azo-groups） or without ZnSB （azo-groups） and colloidal AuNP （gold nanoparticles） of 10, 40 and 80 nm diamete...The authors have prepared suprameolecular systems of chiral Schiffbase ZnAZSB （Zn（II） complexes with azo-groups） or without ZnSB （azo-groups） and colloidal AuNP （gold nanoparticles） of 10, 40 and 80 nm diameters. They exhibited gradual shifts of surface plasmon bands as well as fluorescence bands. The authors observed and discussed induced CD bands on gold nanoparticles from chiral ZnAZSB or ZnSB. Absence of cis-trans photoisomerization of ZnAZSB with AuNP also supported direct contact near the surface of AuNP. Quenching and splitting of fluorescence bands of ZnSB （λex = 550 nm and λem = 400 nm） depending on concentration of ZnSB and size of AuNP also suggested intermolecular （electric） interaction on the surface of AuNE Decrease of the intensity of the CD band around 380 nm resulted from reciprocal induced CD effect due to parallel arrangement of electric transition moments of ZnAZSB or ZnSB and surface of AuNP.展开更多
In this study, author investigated the spectral response of EM （electromagnetic） energy absorption in a colloidal system of Fe3O4 nanoparticles with an average size of 9.50 nm immersed in a 2% aqueous solution of S...In this study, author investigated the spectral response of EM （electromagnetic） energy absorption in a colloidal system of Fe3O4 nanoparticles with an average size of 9.50 nm immersed in a 2% aqueous solution of SDS （sodium dodeci[ sulfate）. The temperature of the nanoparticles and the SDS solution was evaluated by a novel method based on measuring the Q-factor （quality-factor） of a resonant circuit. The Q-factor of the investigated system as a function of the frequency of the EM field was obtained. The nanoparticles-SDS liquid system exhibited a resonance-like behavior of the absorption, where the resonance frequency was about 170 MHz, and the absorption rise up to the resonance frequency was rather slow. The observed absorption of EM energy was accompanied by a small temperature increasing of the system. Measurements of the ESR （electron spin resonance） spectrum of the Fe3O4 nanoparticles have presented a slightly asymmetric singlet with the proportionality factor g = 2 and a line-width of the magnetic field strength △H = 0.1 mT. It was shown that the observed absorption spectrum corresponds to paramagnetic behavior of the investigated nanoparticles.展开更多
Suspended gold nanoparticles have been synthesized via electrochemical method.Fluorescence excitation and emission spectra were obtained using a spectrofluorophotometer.With varying the excitation wavelength,an emissi...Suspended gold nanoparticles have been synthesized via electrochemical method.Fluorescence excitation and emission spectra were obtained using a spectrofluorophotometer.With varying the excitation wavelength,an emission peak fixed at 485 nm has always been observed.We believe that this peak is attributed to the surface plasmon resonance.When the detection wavelength was fixed at 485 nm (0.619×10 15 Hz),a double frequency exciting peak at 242 nm(2×0.619×10 15 Hz), a 3/2 fraction frequency exciting peak at 330 nm (about 3/2×0.619×10 15 Hz)and a 3/4 fraction frequency exciting peak at 640 nm(3/4×0.619×10 15 Hz)display.The nonlinear exciting peak at 640 nm corresponds to the two-photon absorption.Therefore,as the excitation wavelength is at 320 and 640 nm respectively,single-photon and two-photon absorption induced surface plasmon resonance emission peaks were observed. These nonlinear surface plasmon resonance emission characters of Au colloidal nanoparticles make it possible to enhance the sensitivity of conventional surface plasmon resonance device.展开更多
The appropriate choice of chemical composition of a metallic precursor, which produces the basic structure units in the growth process of nanocrystals, is a high priority in the synthesis of metal--especially Au--nano...The appropriate choice of chemical composition of a metallic precursor, which produces the basic structure units in the growth process of nanocrystals, is a high priority in the synthesis of metal--especially Au--nanoparticles. In the present work, Au seeds （prepared by the reduction of Au3＋ solution with NaBI~ in the presence of cetyltrimethylammonium bromide （CTAB）） have been used to initiate the growth of Au nanoparticles from two different Au precursors. When an aqueous Au＋ solution prepared in the presence of CTAB micelles was treated with ascorbic acid in the presence of the gold seeds, a high yield （up to 92%） of gold nanoparticles was obtained. By varying the volume of the seed solution with a fixed amount of Au＋, we can effectively control the morphological transformation of the resulting Au nanoparticles from cubes to octahedra. When an aqueous Au3＋ solution was prepared in the presence of CTAB micelles and treated with ascorbic acid in the presence of the gold seeds, smaller yields of Au nanoparticles were obtained. A preliminary growth mechanism has been proposed based on the changes induced by varying the amount of ascorbic acid and the ratio of the concentration of Au＊ to the number of seeds.展开更多
The van der Waals force originates from the electromagnetic interaction between quantum fluctuationinduced charges. It is a ubiquitous but subtle force which plays an important role and has a wide range of application...The van der Waals force originates from the electromagnetic interaction between quantum fluctuationinduced charges. It is a ubiquitous but subtle force which plays an important role and has a wide range of applications in surface related phenomena like adhesion, friction,and colloidal stability. Calculating the van der Waals force between closely spaced metallic nanoparticles is very challenging due to the strong concentration of electromagnetic fields at the nanometric gap. Especially, at such a small length scale, the macroscopic description of the dielectric properties no longer suffices. The diffuse nonlocal nature of the induced surface electrons which are smeared out near the boundary has to be considered. Here,we review the recent progress on using three-dimensional transformation optics to study the van der Waals forces between closely spaced nanostructures. Through mapping a seemingly asymmetric system to a more symmetric counterpart, transformation optics enables us to look into the behavior of van der Waals forces at extreme length scales,where the effect of nonlocality is found to dramatically weaken the van der Waals interactions.展开更多
文摘In the solution containing ammonia,silver nitrate was reduced by tartaric acid,and nano-silver colloids were generated.The products were characterized by transmission electron microscope(TEM) and X-ray diffraction(XRD).The results show that the average size of silver colloid particles is 25-30 nm and the shape is near-spherical.Researches on the character of resonance light scattering(RLS) of nano-silver colloid indicates that the strongest RLS peak of nano-silver colloid appeares at 447 nm.When BSA adding into the nano-silver colloid solution,the RLS peaks intensity was quenched.Based on this,a novel and simple method of determination of BSA was developed.Under optimum conditions,the linear response is over the range of 2.5pg/mL～2.5×106 pg/mL.
文摘The authors have prepared suprameolecular systems of chiral Schiffbase ZnAZSB （Zn（II） complexes with azo-groups） or without ZnSB （azo-groups） and colloidal AuNP （gold nanoparticles） of 10, 40 and 80 nm diameters. They exhibited gradual shifts of surface plasmon bands as well as fluorescence bands. The authors observed and discussed induced CD bands on gold nanoparticles from chiral ZnAZSB or ZnSB. Absence of cis-trans photoisomerization of ZnAZSB with AuNP also supported direct contact near the surface of AuNP. Quenching and splitting of fluorescence bands of ZnSB （λex = 550 nm and λem = 400 nm） depending on concentration of ZnSB and size of AuNP also suggested intermolecular （electric） interaction on the surface of AuNE Decrease of the intensity of the CD band around 380 nm resulted from reciprocal induced CD effect due to parallel arrangement of electric transition moments of ZnAZSB or ZnSB and surface of AuNP.
文摘In this study, author investigated the spectral response of EM （electromagnetic） energy absorption in a colloidal system of Fe3O4 nanoparticles with an average size of 9.50 nm immersed in a 2% aqueous solution of SDS （sodium dodeci[ sulfate）. The temperature of the nanoparticles and the SDS solution was evaluated by a novel method based on measuring the Q-factor （quality-factor） of a resonant circuit. The Q-factor of the investigated system as a function of the frequency of the EM field was obtained. The nanoparticles-SDS liquid system exhibited a resonance-like behavior of the absorption, where the resonance frequency was about 170 MHz, and the absorption rise up to the resonance frequency was rather slow. The observed absorption of EM energy was accompanied by a small temperature increasing of the system. Measurements of the ESR （electron spin resonance） spectrum of the Fe3O4 nanoparticles have presented a slightly asymmetric singlet with the proportionality factor g = 2 and a line-width of the magnetic field strength △H = 0.1 mT. It was shown that the observed absorption spectrum corresponds to paramagnetic behavior of the investigated nanoparticles.
文摘Suspended gold nanoparticles have been synthesized via electrochemical method.Fluorescence excitation and emission spectra were obtained using a spectrofluorophotometer.With varying the excitation wavelength,an emission peak fixed at 485 nm has always been observed.We believe that this peak is attributed to the surface plasmon resonance.When the detection wavelength was fixed at 485 nm (0.619×10 15 Hz),a double frequency exciting peak at 242 nm(2×0.619×10 15 Hz), a 3/2 fraction frequency exciting peak at 330 nm (about 3/2×0.619×10 15 Hz)and a 3/4 fraction frequency exciting peak at 640 nm(3/4×0.619×10 15 Hz)display.The nonlinear exciting peak at 640 nm corresponds to the two-photon absorption.Therefore,as the excitation wavelength is at 320 and 640 nm respectively,single-photon and two-photon absorption induced surface plasmon resonance emission peaks were observed. These nonlinear surface plasmon resonance emission characters of Au colloidal nanoparticles make it possible to enhance the sensitivity of conventional surface plasmon resonance device.
基金Acknowledgements This work was supported by National Basic Research Program of China （973 Program No. 2009CB930703） and National Natural Science Foundation of China （No. 21033007）. We thank Dr. Jiawei Yan, Yongli Zheng, and Haixin Lin for helpful discussion. We also thank Zhaobin Chen for ICP-AES measurements.
文摘The appropriate choice of chemical composition of a metallic precursor, which produces the basic structure units in the growth process of nanocrystals, is a high priority in the synthesis of metal--especially Au--nanoparticles. In the present work, Au seeds （prepared by the reduction of Au3＋ solution with NaBI~ in the presence of cetyltrimethylammonium bromide （CTAB）） have been used to initiate the growth of Au nanoparticles from two different Au precursors. When an aqueous Au＋ solution prepared in the presence of CTAB micelles was treated with ascorbic acid in the presence of the gold seeds, a high yield （up to 92%） of gold nanoparticles was obtained. By varying the volume of the seed solution with a fixed amount of Au＋, we can effectively control the morphological transformation of the resulting Au nanoparticles from cubes to octahedra. When an aqueous Au3＋ solution was prepared in the presence of CTAB micelles and treated with ascorbic acid in the presence of the gold seeds, smaller yields of Au nanoparticles were obtained. A preliminary growth mechanism has been proposed based on the changes induced by varying the amount of ascorbic acid and the ratio of the concentration of Au＊ to the number of seeds.
基金partially supported by the Gordon and Betty Moore Foundation (J. B. P.)the Royal Commission for the Exhibition of 1851 (R. Z.)+2 种基金the Leverhulme Trust (Y. L. and J. B. P.)the MOE Ac RF Tier 2 (Y. L.)the Program Grant (11235150003) from NTU-A*STAR Silicon Technologies Centre of Excellence (Y. L.)
文摘The van der Waals force originates from the electromagnetic interaction between quantum fluctuationinduced charges. It is a ubiquitous but subtle force which plays an important role and has a wide range of applications in surface related phenomena like adhesion, friction,and colloidal stability. Calculating the van der Waals force between closely spaced metallic nanoparticles is very challenging due to the strong concentration of electromagnetic fields at the nanometric gap. Especially, at such a small length scale, the macroscopic description of the dielectric properties no longer suffices. The diffuse nonlocal nature of the induced surface electrons which are smeared out near the boundary has to be considered. Here,we review the recent progress on using three-dimensional transformation optics to study the van der Waals forces between closely spaced nanostructures. Through mapping a seemingly asymmetric system to a more symmetric counterpart, transformation optics enables us to look into the behavior of van der Waals forces at extreme length scales,where the effect of nonlocality is found to dramatically weaken the van der Waals interactions.
