自组装法制备团簇Ag纳米结构衬底及其SERS

采用自组装方法,在3-Aminopropyltrimethoxysilane(APS)分子修饰后的玻璃衬底表面,获得了二维Ag纳米结构衬底。在波长为532nm激光激发下,研究了沉积在衬底表面的Rhodamine 6G(Rh6G)分子的拉曼光谱特性。结果表明,制备的二维Ag纳米结构衬底具有强的拉曼增强特性,增强因子可以达到107倍。这说明,在外光场作用下,制备的Ag纳米结构衬底表面能够形成的强局部电磁场分布,可以有效提升探针分子的光谱辐射效率,从而获得高增强拉曼散射。     

具有分形结构Ag纳米衬底的荧光增强效应

利用电化学沉积方法,制备出具有分形结构的Ag纳米荧光增强衬底。实验中,采用532nm连续光激发居于Ag纳米结构衬底表面附近的罗丹明6G(Rh6G)荧光分子,结果表明,具有分形结构的Ag纳米金属衬底对沉积在其表面的Rh6G分子表现出明显的荧光增强效应。根据局域场增强理论对所得实验结果进行分析,经过电化学方法制备出的分形Ag纳米结构,在外电磁场激发下能够形成较强的局域电磁场分布,从而有效地激发Rh6G荧光分子,增强其荧光辐射强度。     

自组装法制备Au纳米结构衬底及其表面增强荧光效应研究

采用自组装方法,在(APS)分子修饰后的玻璃衬底 表面,制备得 到Au纳米结构衬底。采取激光光谱学方法,研究所制备衬底对沉积其表面的Rhodamine 6G(R h6G) 分子的荧光辐射增强效应。实验发现,利用自组装方法制备的Au纳米结构衬底具有较强的荧 光增 强特性。理论分析表明,制备的Au纳米结构在外光场激发下,所形成的强局部电磁场分布 能够有效提升探针分子的电子跃迁速率,从而实现增强荧光效应。     

Ag纳米粒子修饰多模光纤的拉曼增强特性实验

为了分析研究光纤表面增强拉曼散射(SERS)探针 的拉曼增强特性,采用简单廉价的化学方法制备Ag纳米颗粒修饰 光纤SERS探针,采用罗丹明6G(R6G,Rhodamine 6G)作为探针分子进行了不同浓度R6G溶 液(10－7~10－9M)的拉曼测试实 验和浓度为10－6M的R6G溶液的Time-course SERS Mapping实验,研究了该光纤 SER S探针的拉曼增强特性,制备的光纤SERS 探针样品检测R6G的极限浓度低至10－9M;在Time-course SE RS Mapping实验中,分 析验证了探针分子溶液蒸发过程对光纤 SERS探针的拉曼增强特性的影响。研究表明,由于制备的光纤SERS探针对荧光噪声没有抑 制作用,导致所测得探针分子 的拉曼光谱受探针分子溶液状态、测试方式的极大影响。当溶液充足时(浸泡状态),所测 光谱信号荧光噪声与有效拉曼光 谱信号都比较大;在溶液干燥过程中,所测光谱信号荧光噪声与有效拉曼光谱信号都减少, 但荧光噪声减小幅度远大于拉曼光谱信号。     

修饰银纳米粒子的石墨烯泡沫镍衬底制备及其SERS活性研究

为了解决表面增强拉曼散射(SERS)衬底的吸附性差、稳定性低以及灵敏度不高的问题,设计了一种沉积银纳米粒子的石墨烯泡沫镍SERS衬底,并进行了实验研究.利用化学气相沉积法在泡沫镍衬底上生长石墨烯,并通过溶液沉积的方法将合成的银纳米粒子沉积在石墨烯泡沫镍衬底表面,烘干后制备成石墨烯泡沫镍修饰银纳米粒子的新型SERS衬底.采用罗丹明6G(R6G)对SERS衬底进行拉曼实验研究,结果表明石墨烯能够较好地淬灭SERS衬底的背景荧光;泡沫镍的独特三维结构能够增大衬底对检测分子的吸附;同时,银纳米粒子也可大幅增强衬底的SERS活性.而修饰了银纳米粒子的石墨烯泡沫镍新型衬底同时具有以上优异特性,是一种具有很大应用潜力的新型SERS衬底.     

C层包覆Ag纳米颗粒基底的表面增强拉曼散射研究

Ag纳米结构是最常用的表面增强拉曼散射(SERS) 活性基底,缺点是Ag的化学稳定性和 生物相容性比较差。为此,利用化学方法合成了一种新型的SERS活性基底—纳米碳层包覆的 Ag(Ag@C)纳米颗粒。利用透射电子显微镜(TEM)和紫外- 可见吸收光谱对制备的核壳结构纳米颗粒进行了表征,并研究了颗粒的SERS活性。结果表明 ,罗丹明6G(R6G)、结晶紫(CV)和孔雀石绿(MG)分子在Ag@C悬浮液中的SERS光谱强度 与在Ag胶中的SERS光谱强度相比显著增强。根据光谱 的变化规律推断,额外的增强来自于化学增强。由于C层的存在,相比于Ag纳米颗粒, Ag@C颗粒的化学稳定性和生物相容性都有所改进。     

蒸发过程对碳纳米管复合结构拉曼增强特性的影响

为了分析探针分子水溶液蒸发过程对三维基底的表面增强拉曼散射(SERS)特性的影响,利用磁控溅射和高温退火的方法制备了银纳米颗粒修饰垂直排列的碳纳米管阵列(Ag/CNTs)三维复合结构样品。采用time-course SERS mapping测试方法,分别以1μmol/L罗丹明6G(R6G)和10-2μmol/L孔雀石绿(MG)作为探针分子,进行了相应的实验。研究表明:随着蒸发时间逐渐增加,探针分子的拉曼信号先增强后减弱。分析其主要原因:探针分子溶液在蒸发过程中,由于毛细力的作用,引起探针分子与三维结构之间"热点"的变化,从而带来电磁场增强特性的变化;此外,聚焦深度和浓度的变化也影响拉曼信号。     

Ag纳米颗粒对Er3+/Yb3+共掺铋锗酸盐玻璃上转换发光性能的影响

采用熔融退火法制备了Er³⁺/Yb³⁺共 掺复合银(Ag)纳米颗粒的铋锗酸盐玻璃,对玻璃样品 进行物理性质、透射电镜(TEM)图像和光谱性能测试,分析了铋锗酸盐玻璃样品中Er³⁺的上转换 发光机理。研究表明:随着退火温度的增加,Ag纳米颗粒不断析出,绿光(527nm波长 )和红光(661nm波长)发光强度都得到了较大增强,在420℃时,上转换发光强度分别为未掺 杂AgCl时的4.45和4.22倍。其上转换发光增强的原因归结于Ag 纳米颗粒表面等离子体共振(SPR)导致局域场电场增强和Ag⁰→Er³⁺的能量转移。     

癸烷硫醇修饰的金/银SERS衬底用于PCB-77检测的研究

通过模板法制备了强SERS活性的“球加片”Au/Ag纳米结构阵列,并利用这种纳米衬底对PCB-77分子的SERS光谱进行了研究。结果表明,尽管该纳米结构能够检测到PCB-77分子的SERS特征峰,但信噪比低。利用癸烷硫醇中的巯基与贵金属之间相互作用,实现了癸烷硫醇分子对纳米结构表面的功能化修饰,研究发现此时PCB-77分子的SERS光谱质量得到了明显改善。并且,这种“球加片”衬底的癸烷硫醇分子最优修饰时间为36小时,利用经36小时修饰后的纳米衬底,极大地提高了PCB-77的SERS光谱特征峰的强度。     

纳米金修饰碳纳米管阵列结构的表面增强拉曼散射

研究了纳米金粒子修饰碳纳米管阵列结构的表面增强拉曼散射性能.通过FDTD理论模拟仿真了不同粒径纳米金颗粒的场强分布;并采用化学还原的方法制备出直径分别为20、40和60 nm三种不同粒径的金颗粒,然后将纳米金粒子修饰到有序定向的碳纳米管阵列表面,并将该结构作为表面增强拉曼基底.FDTD软件仿真结果表明,60 nm粒径的纳米金颗粒周围场强分布最强,是入射场场强的15倍.同时将罗丹明6G溶液用于测试几组不同尺寸的金颗粒对拉曼散射光强的影响,发现60 nm金颗粒对R6G拉曼信号增强最大.FDTD理论模拟仿真和罗丹明6G溶液实验测试结果表明:金颗粒尺寸在20～60 nm内,颗粒尺寸越大,拉曼散射光的光强越大.     

Tailored Plasmonic Gratings for Enhanced Fluorescence Detection and Microscopic Imaging

The ability to precisely control the pattern of metallic structures at the micro‐ and nanoscale for surface plasmon coupling has been demonstrated to be essential for signal enhancement in fields such as fluorescence and surface‐enhanced Raman scattering. In the present study, a series of silver coated gratings with tailored duty ratio and depth and a periodical pitch of 400 nm are designed and implemented. The influence of the grating profile on plasmonic properties and the corresponding enhancement factor are investigated by angular scanning measurement of reflectivity and fluorescence intensity and by finite difference time domain simulation. The application of the substrate in the enhanced fluorescence imaging detection of labeled protein is also investigated. This substrate has a wide range of potential applications in areas including biodiagnostics, imaging, sensing, and photovoltaic cells.     

两种基底对中药溶液喇曼光谱增强作用的比较

为了对比分析TiO₂-AgNPs薄膜与银胶纳米颗粒溶液两种表面增强喇曼光谱散射（SERS）基底对中药溶液样品的SERS增强效果，选取中药附子溶液作为实验样品，分别采用两种SERS基底通过喇曼散射实验取得其表面增量喇曼光谱，并进行了解析对比。结果表明，TiO₂-AgNPs薄膜与银胶纳米颗粒溶液两种SERS基底都对中药附子溶液的喇曼散射光谱起到了明显的增强作用；TiO₂-AgNPs薄膜的增强效果相对于银胶纳米颗粒溶液更为敏感，如在喇曼位移1398cm-1的相对峰强比，TiO₂-AgNPs薄膜基底为27.85%，银胶纳米颗粒溶液基底为11.97%，但其具有易氧化、可用时间短、制备难度大、可重复性不高等缺点，因此更适于样品成分的精确鉴定，银胶纳米颗粒溶液具有制备更简单、使用时间长、稳定性和重复性好等优点，适于大量样品成分确定对比的检测；两种基底对中药溶液样品的SERS增强各有优势。此结果对国内外利用SERS技术分析中药有效成分的基底选择有一定参考作用。     

Fabrication of a network structure SERS substrate and the application in ultra-sensitive crystal violet detection

A network structure surface-enhanced Raman scattering(SERS)-active substrate is fabricated by adding Ag sol dropwise on adhesive tape.Scanning electron microscope(SEM) is employed to characterize the structure of the as-prepared substrate.The substrate shows great SERS enhancement ability and good uniformity by using p-aminothiophenol(PATP) as probe molecules.The detection of crystal violet(CV) in aqueous solution is demonstrated,and the detection limit is as low as 10-12M with the aid of the substrate.The results indicate that the proposed method is a potential approach for the fabrication of SERS substrates.     

亚波长单金属槽电磁场增强分析

针对金属微纳结构在表面增强拉曼光谱领域的应用,研究了金属基底亚波长单槽结构产生的电磁场增强。采用全矢量方法严格计算了平面波照明下金属槽外部区域电磁场的分布情况。建立了法布里-珀罗(F-P)半解析模型,该模型能够精确预言全矢量方法的计算结果,能够节省设计最优槽深的计算量。基于该模型分析了金属槽外部区域电场增强的物理机制,结果表明达到相长叠加共振状态的金属槽内基模在槽外空间中激励的透射电场是金属槽外空间中电场增强的主要来源。研究了槽外空间电场增强的范围,结果表明对于不同的槽宽和入射波长,在垂直距离槽口0.1倍波长的范围内电场增强较为明显,在该范围之外,电场增强因子迅速衰减到1的数量级。     

Fabrication and characterization of silver deposited micro fabricated quartz arrays for surface enhanced Raman spectroscopy (SERS)

In this work microfabricated silver coated two-dimensional quartz gratings are developed for the use as plasmonic arrays for surface enhanced Raman spectroscopy (SERS). The SERS technique provides enormous signal intensity and fingerprint specificity and is a powerful tool in chemical and biological applications. However, the acceptance and the employment of the SERS technique for (bio)analytical devices depends on the availability of suitable substrates with homogenous field enhancement properties. Here, the fabrication and optimization process of the SERS array with an enhancement factor between 10⁵ and 10⁶ is introduced.     

Copper Nanoparticles Grafted on a Silicon Wafer and Their Excellent Surface‐Enhanced Raman Scattering

Copper nanoparticles grafted on a silicon wafer are fabricated by reducing copper ions with silicon–hydrogen bonds and assembling them in situ on the Si wafer. The nanoparticles, with an average size of 20 nm, grow uniformly and densely on the Si wafer, and they are used as substrates for surface‐enhanced Raman scattering. These substrates exhibit excellent enhancement in the low concentration detection (1 × 10^?9 M ) of rhodamine 6G with an enhancement factor (EF) of 2.29 × 10⁷ and a relative standard deviation (RSD) of <20%. They are also employed to detect sudan‐I dye with distinguished sensitivity and uniformity. The results are interesting and significant because Cu substrates are otherwise thought to be poor. These effects might provide new ways to think about surface‐enhanced Raman scattering based on Cu substrates.     

Plasmon‐Enhanced Photocurrent of Photosynthetic Pigment Proteins on Nanoporous Silver

In a quest to fabricate novel solar energy materials, the high quantum efficiency and long charge separated states of photosynthetic pigment‐proteins are being exploited through their direct incorporation in bioelectronic devices. In this work, a biohybrid photocathode comprised of bacterial reaction center‐light harvesting 1 (RC‐LH1) complexes self‐assembled on a nanostructured silver substrate yields a peak photocurrent of 166 μA cm^?2 under 1 sun illumination, and a maximum of 416 μA cm^?2 under 4 suns, the highest reported to date on a bare metal electrode. A 2.5‐fold plasmonic enhancement of light absorption per RC‐LH1 complex is observed on the rough silver substrate. This plasmonic interaction is assessed using confocal fluorescence microscopy, revealing an increase of fluorescence yield, and radiative rate of the RC‐LH1 complexes, signatures of plasmon‐enhanced fluorescence. Nanostructuring of the silver substrate also enhanced the stability of the protein under continuous illumination by almost an order of magnitude relative to a nonstructured bulk silver control. Due to its ease of construction, increased protein loading capacity, stability, and more efficient use of light, this hybrid material is an excellent candidate for further development of plasmon‐enhanced biosensors and biophotovoltaic devices.     

Significantly Increased Raman Enhancement on MoX2 (X = S,Se) Monolayers upon Phase Transition

2D transition metal dichalcogenide (TMD) materials have been recognized as active platforms for surface‐enhanced Raman spectroscopy (SERS). Here, the effect of crystal structure (phase) transition is shown, which leads to altered electronic structures of TMD materials, on the Raman enhancement. Using thermally evaporated copper phthalocyanine, solution soaked rhodamine 6G, and crystal violet as typical probe molecules, it is found that a phase transition from 2H‐ to 1T‐phase can significantly increase the Raman enhancement effect on MoX₂ (X = S, Se) monolayers through a predominantly chemical mechanism. First‐principle density functional theory calculations indicate that the significant enhancement of the Raman signals on metallic 1T‐MoX₂ can be attributed to the facilitated electron transfer from the Fermi energy level of metallic 1T‐MoX₂ to the highest occupied molecular orbital level of the probe molecules, which is more efficient than the process from the top of valence band of semiconducting 2H‐MoX₂. This study not only reveals the origin of the Raman enhancement and identifies 1T‐MoSe₂ and 1T‐MoS₂ as potential Raman enhancement substrates, but also paves the way for designing new 2D SERS substrates via phase‐transition engineering.     

Efficiency enhancement of organic light-emitting devices by using honeycomb metallic electrodes and two-dimensional photonic crystal arrays

In this paper, a facile fabrication technique called nanosphere lithography combining with two-step reactive ion etching method for patterning honeycomb metallic electrode with high transparency and excellent uniformity is demonstrated. The patterning silver electrode with 15-nm film thickness and 68.6% fill-factor was used as the organic light-emitting diode (OLED) anode, which showed an average transmittance of 77.4% and sheet resistance of 30.7 Ω/□. The current efficiency is 8.35 cd/A for the OLED with patterned silver anode under 100 cd/m² operation brightness, which was 47% higher than the device with indium tin oxide (ITO) anode. After applying the polystyrene nanosphere to form a photonic crystal array onto the device, the extracted light from organic mode can be further coupled out from device substrate mode. The overall luminous enhancement of the device with the combination of internal honeycomb metallic anode and external photonic crystal array is 115% higher than the traditional ITO-based OLED.