AFM Tip-Directed ID and 0D Assembling of Colloidal Au Nanoparticles on Silicon

Colloidal Nanoparticles have received renewed interests recently from the viewpoint of nanoscale science and technology. Using chemical assembling techniques, one can fabricate well-organized 2D nanoparticle arrays on solid substrates and use it as the Coulomb island for room temperature single electron tunneling^[1], as nanoelectrode for electrochemistry studies^[2], as active substrate for surface enhanced Raman scattering (SERS)^[3,4],as lithographic mask for fabrication of nanostructures^[5] and etc.     

The Cross Link of Surface Enhanced Raman Scattering with Surface Science and Nanoscale Science

The discovery of surface enhanced Raman scattering (SERS) in the mid-1970s impacted on the surface science community because of its remarkably high and unique surface sensitivity. Surface roughness in scale of 10~100 nm have been found necessary to produce the giant SERS signal. In this paper we will show that SERS is indeed one of the important phenomena not only in surface science but also in nanoscale science^[1].     

A Comparative Study on the Influence of Submonolayer Coverage Sn on SERS of Au and Pt Substrates

Since the discovery of the surface enhanced Raman scattering (SERS) in mid-1970's,great efforts have been devoted to understand the enhancement mechanism as well as to extend the SERS system and application. There has been a consensus that the electromagnetic enhancement (EM) and chemical enhancement are the two important SERS mechanisms but each of them can only explain some of experimental results^[1,2] The EM mechanism relies on the surface plasmon resonance under a proper incident laser excitation. Strong EM enhancement has been observed on metals such as Cu, Ag and Au but not on transition metals such as Pt. However, the surface electronic properties can be modulated through submonolayer quantity modification of foreign metal atoms, hi this paper, we report a comparative study on SERS of Au and Pt in the presence of underpotentially deposited (UPD) submonolayer Sn.     

Surface-enhanced Raman Scattering Technology Based on WO3 Film for Detection of VEGF

With the advancement of nanomaterials for surface-enhanced Raman scattering(SERS) detection, a deeper understanding of the chemical mechanism(CM) and further applications has been achieved. Herein, we prepared a porous tungsten trioxide(WO₃) film by the pulse electrodeposition method, and constructed a WO₃ film SERS aptasensor. With methylene blue(MB) as the adsorption molecule, the developed WO₃ film SERS aptasensor revealed remarkable Raman activity. Through experimental data and theoretical calculations, we found that the significant SERS enhancement[enhancement factor(EF)=1.5×10⁶] was due to the CM based on charge transfer and molecular resonance. Utilizing the Raman response of MB on the WO₃ film and specific aptamers, we successfully developed the aptamer sensor by covalently attaching the MB modified aptamer to the WO₃ film. The sensor realized the specific and sensitive determination of vascular endothelial growth factor(VEGF) with the detection limit down to 8.7 pg/mL. In addition, the developed aptasensor indicated the excellent selectivity among other interferences, such as metal ions, reactive oxygen species(ROS), and proteins. This WO₃ film SERS aptasensor not only contributed to the study of the enhancement mechanism of semiconductor material, but also provided a powerful platform for the sensitive detection of VEGF, possessing a great potential in the real-time monitoring of biomarkers of glioblastoma in vitro.     

An investigation of the surface-enhanced Raman scattering effect from new substrates of several kinds of nanowire arrays

Silver, titanium, nickel, and aluminum nanowire arrays with diameters from 90 to 110 nm were prepared on AAO templates by laser molecular beam epitaxy. On the several kinds of nanowire arrays, high-quality surface-enhanced Raman scattering (SERS) spectra of probe molecules of the red dye Sudan II (C(18)H(16)N(2)O) were obtained. In particular, the SERS spectrum of Sudan II on an aluminum nanowire array is reported for the first time.     

吡啶在几种金属纳米线阵列上的表面增强喇曼光谱

近20多年来利用表面增强喇曼光谱（SERS）的研究还仅限于Ag,Au,Cu这三种具有强SERS效应的金属,最近,田中群等利用合适的表面处理方法和共焦曼光谱技术成功地获得了许多无机离子和有机小分子吸附在一系列的过渡金属（如Pt,Ni,Fe,Pd,Rh,Co,Ru等）上的SERS光谱,拓宽了SERS的应用范围,但这些表面处理方法对基底进行处理时存在着较大的随机性,从而导致对所得SERS信号的解释困难。近年来通过自组装膜、模板合成等技术可得比较有序具有强SERS效应的或表面,例如Nie等最近发现尺寸分布狭窄的Ag溶胶粒子（约80－100nm）能诱导出巨大的SERS增强;Freeman和C tffumj m jf rbutb uqf At A 体微粒组装在聚合物基底上,制得高活性的SERS基底,以上工作都表明制备有序纳米级金属颗粒表面将推动SERS的应用和机理研究,迄今,3半导体纳米线阵列上的喇曼光谱已有报道,而利用金属纳米线阵列作为SERS基底除半于样模合成法制备的Ag纳米线阵列上的SERS之外,尚未见其它相关报道,本文主要研究样模合成法制备金属纳米线的过程,并以此为基底研究吡啶吸附的SERS光谱。     

Large-area highly-oriented SiC nanowire arrays: synthesis, Raman, and photoluminescence properties

Large-area highly oriented SiC nanowire arrays have been fabricated by chemical vapor reaction using an ordered nanoporous anodic aluminum oxide (AAO) template and a graphite reaction cell. Their microstructures were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and high-resolution transmission electron microscopy. The results show that the nanowires are single-crystalline beta-SiC's with diameters of about 30-60 nm and lengths of about 8 microm, which are parallel to each other, uniformly distributed, highly oriented, and in agreement with the nanopore diameter of the applied AAO template. The nanowire axes lie along the [111] direction and possess a high density of planar defects. Some unique optical properties are found in the Raman spectroscopy and photoluminescence emission from oriented SiC nanowire arrays, which are different from previous observations of SiC materials. The growth mechanism of oriented SiC nanowire arrays is also analyzed and discussed.     

覆银聚酰亚胺纳米棒阵列的制备及其SERS特性

通过在聚酰亚胺(PI)膜表面进行氧等离子体刻蚀得到纳米棒阵列,并溅射Ag膜形成了覆银聚酰亚胺纳米棒阵列。利用该方法能够简单快捷地制备出具有较强活性且结构可调的表面增强拉曼散射(SERS)衬底。通过改变氧等离子体刻蚀时间和溅射Ag膜厚度可以调节覆银PI纳米棒的间隙、密度和直径。通过对探针分子尼罗兰(NB)测试表征了覆银PI纳米棒衬底的SERS增强能力。通过改变氧等离子体刻蚀时间和Ag膜溅射厚度实现了衬底SERS增强能力的调节。在氧等离子体刻蚀时间为30 s和溅射Ag膜厚度为70 nm时,衬底的SERS增强能力达到最强,并且其拉曼信号展现出较好的一致性。     

Uniform arrays of gold nanoparticles with different surface roughness for surface enhanced Raman scattering

Uniform arrays of coarse and smooth gold nanoparticles with diameter about 130 nm were successfully synthesized through seed-mediated growth method, separately. Scanning and transmission electron microscopy (SEM and TEM) and X-ray diffraction (XRD) have been used to study the formation and structure of the nanocomposites. The high enhancement factor for surface-enhanced Raman scattering of coarse and smooth gold nanoparticles were estimated to be about 3.1 × 10⁶ and 2.0 × 10⁶, respectively. It is evident that the coarse gold nanostructures has higher influence factor than the smooth gold nanostructures. Therefore, these unique properties of the coarse Au nanoparticles appear to be very promising for applications as high-performance SERS substrates.     

Investigation of the effects of the local environment on the surface-enhanced Raman spectra of striped gold/silver nanorod arrays

The effects of the local environment on surface-enhanced Raman scattering (SERS) spectra utilizing gold, silver, and gold/silver striped nanorod array substrates was investigated. The arrays were fabricated using an electrochemical metal deposition into an anodic aluminum oxide template. The analyte chosen for this study was p-nitroso-N,N-dimethylaniline (p-NDMA), which has an electronic structure that is highly sensitive to its surrounding environment. Changes in the peak positions and peak ratios were used to probe the influence of water and the striping pattern on the SERS signal of p-NDMA. We present the results of the fabrication and characterization of the nanorod array substrates, as well as SERS spectra of p-NDMA in both polar and nonpolar environments and SERS spectra on a variety of striped nanorod arrays. The Raman data suggests that the p-NDMA molecule exists in a more polarized state when bound to the gold as compared to the silver rods. We have attempted to use these differences to determine whether the SERS signal predominantly arises from the tips of the rods or from the interior of the array.     

Semi-quantitative trace analysis of nuclear fast red by surface enhanced resonance Raman scattering

The dye nuclear fast red has been detected and determined semi-quantitatively by means of surface enhanced resonance Raman scattering (SERRS) and surface enhanced Raman scattering (SERS), using laser exciting wavelengths of 514.5 and 632.8 nm, respectively, by employing a citrate-reduced silver colloid. A good linear correlation is observed for the dependence of the intensities of the SERRS bands at 989 cm⁻¹ (R=0.9897) and 1278 cm⁻¹ (R=0.9872) on dye concentration over the range 10⁻⁹ to 10⁻⁷ M, when using an exciting wavelength of 514.5 nm. At dye concentrations above 10⁻⁷ M, the concentration dependence of the SERRS signals is non-linear. This is almost certainly due to the coverage of the colloidal silver particles being in excess of a full monolayer of the dye. A linear correlation is also observed for the dependence of the intensities of the SERS bands at 989 cm⁻¹ (R=0.9739) and 1278 cm⁻¹ (R=0.9838) on the dye concentration over the range 10⁻⁸ to 10⁻⁶ M when using an exciting wavelength of 632.8 nm. Strong fluorescence prevented collection of resonance Raman scattering (RRS) spectra from powdered samples or aqueous solutions of the dye using an exciting wavelength of 514.5 nm, but weak bands were observed in the spectra obtained from both powdered and aqueous samples of the dye using an exciting wavelength of 632.8 nm. A study of the pH dependence of SERRS/SERS and UV–VIS absorption spectra revealed the presence of different ionisation states of the dye. The limits of detection for nuclear fast red by SERRS (514.5 nm), SERS (632.8 nm) and visible spectroscopy (535 nm) are 9, 89 and 1000 ng ml⁻¹, respectively.     

Enhancement at the junction of silver nanorods

The enhancement of surface enhanced Raman scattering (SERS) at the junction of linearly joined silver nanorods (31 nm in diameter) deposited in the pores of anodic aluminum oxide templates was studied systematically by excitation with a 632.8 nm laser line. The single and joined silver nanorod arrays showed a similar extinction spectrum when their length was the same. Maximum enhancement was observed from the junction system of two nanorods of the same size with a total length of 62 nm. This length also corresponded to the optimum length of single nanorods for SERS by excitation with a 632.8 nm laser line. The enhancement at the junction was approximately 40 times higher than that of the 31 nm single nanorod, while it was 4 times higher than that of the 62 nm single nanorod. The enhancement factor at the junction after oxide removal was approximately 3.9 x 10 (9).     

4.81%光电转换效率的全固态致密PbS量子点薄膜敏化TiO2纳米棒阵列太阳电池

A compact PbS quantum-dot thin film was prepared using the combination of TiO₂ nanorod arrays and 1, 2-ethanedithiol following the spin-coating assisted successive ionic layer absorption and reaction procedure. Solar cells with the novel structure of FTO/compact PbS quantum-dot thin film sensitized TiO₂ nanorod arrays/spiro-OMeTAD/Au were assembled. Subsequently, the influence of the length of TiO₂ nanorod arrays on the photovoltaic performance of all-solid-state compact PbS quantum-dot thin film sensitized solar cells was evaluated. The corresponding solar cells having TiO₂ nanorod array lengths of 290, 540, and 1040 nm achieved photoelectric conversion efficiencies (PCE) of 2.02%, 4.81%, and 1.95%, respectively. These results reveal that in order to achieve high PCE values with the all-solid-state quantum dot sensitized solar cells, it is very important to balance the hole diffusion length with the loading amount of quantum-dots.     

InSb纳米线阵列的可控制备与光谱表征

采用脉冲电沉积结合阳极氧化铝模板技术制备了不同生长方向的闪锌矿型InSb纳米线阵列. 结果表明, 控制电解液中十二烷基硫酸钠(SDS)的浓度, 可使纳米线的择优生长方向从[400]向[220]方向转变. 利用X射线衍射仪、 场发射扫描电子显微镜、 高分辨透射电子显微镜对所制备纳米线的相组成和微结构进行了表征. 激光拉曼光谱结果表明, 不同生长方向的InSb纳米线阵列的拉曼光谱有明显差异. 与体材料相比, InSb纳米线阵列的红外吸收声子散射峰发生强烈红移, 其吸收带边发生了明显蓝移.     

室温电子还原制备金纳米颗粒与琼脂糖复合膜的表征与应用

利用室温电子还原技术合成了一种金纳米颗粒与琼脂糖复合膜。合成过程采用氩气辉光放电为廉价电子源,方便快捷,绿色环保。通过紫外-可见(UV-Vis)分光光度计、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线衍射(XRD)仪、光电子能谱(XPS)等表征,发现可以通过改变氯金酸浓度调控复合膜中金纳米颗粒的分布,加入聚乙烯吡咯烷酮(PVP)可有效控制金纳米颗粒的形貌。由于复合膜具有金纳米颗粒密集排布的结构,可作为表面增强拉曼散射(SERS)活性基底。实验表明,以对氨基苯硫酚为探针,该复合膜作为SERS基底,SERS平均增强因子超过了106,检测限达到了10-12mol?L-1。除此之外,作为SERS基底,复合膜具有良好的均一性和稳定性。     

取代基对咪唑[4,5-f]-1,10-邻菲罗啉Ru(Ⅱ)配合物的温敏性能影响

合成了3种具有不同取代基的咪唑[4, 5-f]-1,10-邻菲罗啉配体L¹~L³及其Ru(Ⅱ)配合物[Ru(L¹)₃]、[Ru(L²)₃]和[Ru(L³)₃],并进行了表征。这些Ru(Ⅱ)配合物在溶液中具有π→π^*跃迁吸收峰和金属到配体的电荷转移跃迁(MLCT)吸收峰,其发光峰位约为590 nm左右。将Ru(Ⅱ)配合物掺杂到聚甲基丙烯酸甲酯(PMMA)中得到相应的温敏漆。Ru(Ⅱ)配合物在PMMA膜中的吸收峰精细结构消失,且在长波方向663 nm附近有新的发射峰,表明Ru(Ⅱ)配合物在PMMA膜中有聚集。温度升高后,Ru(Ⅱ)配合物在PMMA膜中的发射峰强度逐渐减弱。分别计算了在30~60 ℃和60~90 ℃区间内非辐射活化能E_nr和温度灵敏度S_T。结果表明,具有苯基取代的咪唑[4, 5-f]-1,10-邻菲罗啉配体的[Ru(L¹)₃]配合物,比咪唑[4, 5-f]-1,10-邻菲罗啉Ru(Ⅱ)配合物[Ru(L²)₃]及烷基取代基的咪唑[4, 5-f]-1,10-邻菲罗啉Ru(Ⅱ)配合物[Ru(L³)₃]具有更高的温度灵敏度。     

Pattern and feature designed growth of ZnO nanowire arrays for vertical devices

An approach is demonstrated for growing aligned ZnO nanowire/nanorod arrays following a predesigned pattern and feature with controlled site, shape, distribution, and orientation. The technique relies on an integration of atomic force microscopy (AFM) nanomachining with catalytically activated vapor-liquid-solid (VLS) growth. The pattern and growth locations are defined by the catalyst distribution created by AFM, and the orientation is determined by the epitaxial growth on a single-crystal substrate. The technique opens a variety of possibilities of using nanowire arrays as sensor arrays, piezoelectric antenna arrays, nanolasers, photonic band gap crystal, biosensors, and field emitters with controlled density, location, shape, and distribution according to a designed pattern and feature.     

SERS at structured palladium and platinum surfaces

Palladium and platinum are important catalytic metals, and it would be highly advantageous to be able to use surface enhanced Raman spectroscopy (SERS) to study reactive species and intermediates on their surfaces. In this paper we describe the use of templated electrodeposition through colloidal templates to produce thin (<1 microm) films of palladium and platinum containing close packed hexagonal arrays of uniform sphere segment voids. We show that, even though these films are not rough, when the appropriate film thickness and sphere diameter are employed these surfaces give stable, reproducible surface enhancements for Raman scattering from molecules adsorbed at the metal surface. We report SERS spectra for benzenethiol adsorbed on the structured palladium and platinum surfaces of different thicknesses and void diameters and show that, for 633 nm radiation, enhancements of 1800 and 550 can be obtained for palladium and platinum, respectively.     

热处理对[NiFe/Cu/Co/Cu]_n多层纳米线磁性能的影响

采用双槽控电位法在阳极氧化铝(AAO)模板中制备了有序均一的[NiFe/Cu/Co/Cu]n多层纳米线阵列,并在不同温度下进行了热处理.利用X射线衍射(XRD)对热处理前后多层线的晶体结构进行了测试.考察了不同退火温度对多层线矫顽力、剩磁比、巨磁电阻(GMR)效应、磁灵敏度的影响.随热处理温度升高,多层纳米线中磁性微晶晶型取向越来越明显,晶体结构更均匀;多层纳米线的矫顽力和剩磁比先增大后减小.300°C下多层纳米线矫顽力达到最大值,GMR最大值可达59%,对应的磁电阻灵敏度(SV)为0.233%Oe-1.     

Synthesis,structures and reactivities of poly(pyrazol-1-yl) alkane tetracarbonylmolybdenum (tungsten):x-ray crystal structures of (CH2)2(3,5-Me2Pz)2W(CO)4 and CH2(3,5-Me2Pz)2W(Cl)(CO)3(SnCl3)(Pz:pyrazolyl)

Since S. Trofimenko introduced these isosteric and isoelectronic ligands with poly(1-pyrazolyl)borates^[1],the poly (pyrazolyl)alkane ligands have attracted much attention. Their coordinating behaviour with transition and main group metals has been extensively investigated in recent years^[2]. The coordinating behaviour of bis(3,5-dimethylpyrazol-1-yl)ethane is often different from other poly(pyrazolyl) alkanes^[3]. The VIB metals carbonyl complexes bonded with poly (pyrazolyl)alkanes have novel structures and unusual reactivities^[4,5,6],which encourages us to investigate M-Sn bimetallic complexes with poly(pyrazolyl)alkanes. In this paper, we report the synthesis, characterization and reactivities of poly (pyrazol-1-yl)alkane tetracarbonylmolybdenum (tungsten) with R'SnCl₃(R'=Ph,Cl).