硫化铅掺杂石英玻璃光纤喇曼增强特性研究

普通单模光纤的喇曼增益低,严重制约了喇曼放大器的发展。因此,研究高喇曼增益的光纤具有重要意义。研究了硫化铅掺杂石英玻璃光纤的喇曼散射增强特性。采用改进的化学气相沉积(MCVD)法分别制备出硫化铅掺杂石英玻璃光纤和普通单模光纤样品,并测得其传输损耗谱和喇曼光谱,实验结果表明:硫化铅掺杂石英玻璃光纤具有更强的喇曼散射强度。在不同的泵浦功率条件下,分别进行了喇曼放大实验,相比于普通单模光纤,硫化铅掺杂石英玻璃光纤具有更大的喇曼增益。     

表面增强喇曼光谱的Au@SiO2核壳纳米粒子制备北大核心

研究了核壳纳米颗粒的表面增强喇曼光谱（SERS）,并制备了不同SiO2厚度的Au@SiO2核壳纳米粒子进行喇曼光谱分析测试。首先,采用化学还原法制备出酒红色的金溶胶溶液。接着,添加不同量的正硅酸四乙酯（TEOS）制备了以Au为核、不同厚度SiO2为壳包裹的Au@SiO2核壳纳米粒子。然后,采用紫外-可见光（UV-Vis）和扫描电子显微镜（SEM）对Au@SiO2核壳纳米粒子的结构进行表征。最后,不同SiO2厚度的Au@SiO2核壳纳米粒子和未进行表面修饰的金溶胶溶液中滴入等量质量浓度为0.1 mg/L的罗丹明B,离心干燥后用喇曼光谱仪测试表面增强喇曼光谱效应。结果表明：罗丹明B的检出限可达到2.1×10^-7 mol/L,在扫描范围为300-1 800 cm^-1,激发波长为532 nm的条件下,SERS活性随TEOS用量的增加先增大后减小。TEOS的用量为120μL时,罗丹明B的表面喇曼增强效应最佳。     

食管癌患者血红蛋白表面增强拉曼散射光谱的统计分析

应用表面增强拉曼散射(SERS)光谱技术,以Ag纳米粒子为基底,对24例食管癌患者及20例健康人的血红蛋白样本进行了检测,并采用主成分分析(PCA)与判别分析方法对检测到的光谱数据进行分析。实验得到食管癌患者与健康人血红蛋白SERS光谱存在的区别反映了两组血红蛋白内部物质的含量差异,结果显示,与健康人相比,食管癌患者的血红蛋白中有更多的亚铁离子处于低自旋态。统计分析方法所得的光谱峰值PC得分的三维散点图对食管癌患者与健康人区别也较明显。本文方法的总准确率为91%,诊断灵敏度为96%,诊断特异性为85%。结果表明,通过血红蛋白SERS光谱的检测和统计分析,可为早期食管癌的诊断提供依据。     

多种形貌纳米银的电化学制备及其表面增强拉曼光谱研究

采用电化学沉积的方法制备出球状、棒状、树枝状、立方体状、带孔洞的多面体状的纳米银.扫描电镜的显微观察结果显示,沉积电压不仅影响纳米银的尺寸大小而且对形貌也有重要影响.通过对球状和树枝状纳米银进行的表面增强拉曼光谱(surface-enhanced raman scattering,SERS)的应用研究表明,用电化学沉积...     

表面增强喇曼光谱研究脐橙中亚胺硫磷农药残留

为了证实以团絮状银胶为基底的表面增强喇曼光谱（SERS）技术结合化学计量学方法能有效实现脐橙中农药残留检测,采用德国布鲁克公司的共焦显微喇曼光谱仪,对脐橙中的亚胺硫磷农药残留的快速无损检测进行了研究。通过留一交互验证法得出农药检出限为4.113mg/L,并对SERS光谱进行7种方法的预处理。结果表明,先基线校正后卷积平滑预处理的建模预测效果最好;结合偏最小二乘法建模,预测集的相关系数和预测均方根误差分别为0.904和4.890mg/L,校正集的相关系数和预测均方根误差分别为0.919和3.990mg/L。结果证明了SERS定量分析的科学性和可行性,这对国内水果的生产和出口水果的农药残留检测有一定的参考作用。     

石英光纤中受激喇曼散射光谱形成及其能量转换

将泵浦光产生的受激喇曼散射（ Ｓ Ｒ Ｓ） 光谱看作新的独立的单色光源,在光纤内传播的过程中,每个光源按喇曼增益曲线各自独立地激发新的斯托克光谱, 因此 Ｓ Ｒ Ｓ 光谱曲线是光谱内无数个单色光源之间相互吸收相互放大的结果。据此,建立耦合波方程,利用 Ｒｕｎｇｅ － － Ｋｕｔｔａ方法可以计算 Ｓ Ｒ Ｓ 光谱。文中讨论了一阶斯托克光谱的形成,同阶斯托克光谱内的能量红移现象,高阶斯托克光之间以频移４４０ ｃｍ － １ 传递能量以及频带展宽等问题     

DWDM系统中色散对受激喇曼散射的影响

研究了光纤色散对波分复用(WDM)系统中受激喇曼散射(SRS)非线性效应的影响.提出了一种简便且物理意义明确的分析计算模型,它适合于任意输入信号、任意信道数,以及不同的色散参量.基于该模型,深入分析了两信道光纤通信系统中,各种色散参量下,色散对SRS的影响,得出了色散能减小SRS效应所引起的输出功率的波动的结论,并且给出了在不同色散参量下,输出功率标准差随距离变化的曲线.     

乙醇溶液中后向受激喇曼散射的瞬态效应——亚皮秒喇曼光脉冲的产生

本文报道了在乙醇溶液中实现后向受激喇曼散射光脉冲产生的实验装置和结果,得到了脉宽为280fs、压缩比达100倍的喇曼光脉冲,提出了喇曼超压窄区的概念。     

单壁碳纳米管表面增强拉曼散射的新方法

依据碳纳米管独特的力学性能,在银表面直接研磨单壁碳纳米管(SWCNTs),在形成纳米级粗糙银表面的同时,SWCNTs管也吸附在银表面上,在银表面粗糙程度和SWCNTs厚度适中的区域得到了高质量的表面增强拉曼散射(SERS)谱。理论分析和实验结果表明,该方法是正确可行的。     

一种新的具有双面活性的SERS基底

用二次氧化的方法制得了孔径均一、排列规则的阳极氧化铝模板（AAO,anodic aluminumoxide）。利用磁控溅射的方法,银纳米颗粒被溅射在模板的表面以及孔洞里面,在模板的一面形成一层粗糙的银表面,当把模板放入一定浓度的NaOH溶液中,反面的Al2O3模板被部分地溶解后露出针尖状的银纳米线阵列。用结晶紫作为探针分子,在粗糙银表面（正面）和针尖状的银纳米线阵列面（反面）得到了不同的表面增强拉曼散射（SERS,surface enhanced Raman scattering）光谱,从而证明了两面具有不同的SERS机制。分析表明：正面粗糙的银表面是吸附增强,而反面在存在吸附增强的同时起主要作用的是针尖状的银纳米线阵列构成的天线模型所产生的非吸附的增强。针尖末端的曲率半径极小,会产生极强的局域电磁场,处于这个场中的分子的信号就被大大增强了。     

Supported Faceted Gold Nanoparticles with Tunable Surface Plasmon Resonance for NIR‐SERS

A novel dry plasma methodology for fabricating directly stabilized substrate‐supported gold nanoparticle (NP) ensembles for near infrared surface enhanced Raman scattering (NIR SERS) is presented. This maskless stepwise growth exploits Au‐sulfide seeds by plasma sulfidization of gold nuclei to produce highly faceted Au NPs with a multiple plasmon resonance that can be tuned from the visible to the near infrared, down to 1400 nm. The role of Au sulfidization in modifying the dynamics of Au NPs and of the corresponding plasmon resonance is discussed. The tunability of the plasmon resonance in a broad range is shown and the effectiveness as substrates for NIR SERS is demonstrated. The SERS response is investigated by using different laser sources operating both in the visible and in the NIR. SERS mapping of the SERS enhancement factor is carried out in order to evaluate their effectiveness, stability, and reproducibility as NIR SERS substrates, also in comparison with gold NPs fabricated by conventional sputtering and with the state‐of‐the‐art in the current literature.     

准分子激光增强金属电化学刻蚀特性实验研究

采用248nm KrF准分子激光照射电化学刻蚀中的金属阳极,记录过程中阳极电流的变化,对不同金属的阳极电流 曲线进行对比分析,发现在激光作用的时间内,阳极电流显著增大,激光作用过后,阳极电流迅速减小,而且脉冲频率越高阳 极电流增加的幅度越大,不同的金属阳极电流曲线有所不同,这反映准分子激光对不同金属电化学特性的增强有所差别。     

Self‐Assembled SERS Substrates with Tunable Surface Plasmon Resonances

The fabrication of surface‐enhanced Raman spectroscopy (SERS) substrates that are optimized for use with specific laser wavelength–analyte combinations is addressed. In order to achieve large signal enhancement, temporal stability, and reproducibility over large substrate areas at low cost, only self‐assembly and templating processes are employed. The resulting substrates consist of arrays of gold nanospheres with controlled diameter and spacing, properties that dictate the optical response of the structure. Tunability of the extended surface plasmon resonance is observed in the range of 520–1000 nm. It is demonstrated that the enhancement factor is maximized when the surface plasmon resonance is red‐shifted with respect to the SERS instrument laser line. Despite relying on self‐organization, site‐to‐site enhancement factor variations smaller than 10% are obtained.     

High enhancement factor of Au nano triangular prism structure for surface enhanced coherent anti-Stokes Raman scattering

Coherent anti-Stokes Raman scattering spectroscopy(CARS) is a well-known detecting tool in biosensing and nonlinear spectroscopy. It can provide a non-invasive alternative without the need for exogenous labels, while the enhancement factor for surface plasmon resonances(SPR) are extensively used to increase the local field close to the oscillators and which can obtain high enhancement. In this work, we investigate the enhancement factor of our structure for surface-enhanced coherent anti-Stokes Raman scattering. The absorption spectrum of the structure has been studied, a wide range of absorption has been realized. The enhancement can be as high as 10¹⁶ over standard CARS. Our design is very useful for improving the enhancement factor of surface-enhanced coherent anti-Stokes Raman scattering.     

树枝状Ag基底的制备及其SERS活性研究

研究了一种表面增强拉曼散射(SERS)活性Ag基底的制备新方法。通过电化学方法和液相生长方法相结合在金属Al表面制备SERS活性Ag膜。用扫描电子显微镜(SEM)表征Ag膜的表面形貌,以结晶紫(C25 H30N3Cl·H2O)为拉曼探针分子,研究了基底的SERS增强效果。研究表明:结晶紫分子吸附在Ag膜表面的SERS强度随电沉积时间的增加呈现先增强后减弱的趋势;进一步的Ag增强剂和引发剂的混合溶液对电沉积Ag膜的浸泡处理可以调节基底Ag膜的结构形态,增强电沉积基底Ag膜的SERS活性。     

Facile Fabrication of High‐Density Sub‐1‐nm Gaps from Au Nanoparticle Monolayers as Reproducible SERS Substrates

The fabrication of ultrasmall nanogaps (sub‐1 nm) with high density is of significant interest and importance in physics, chemistry, life science, materials science, surface science, nanotechnology, and environmental engineering. However, it remains a challenge to generate uncovered and clean sub‐1‐nm gaps with high density and uniform reproducibility. Here, a facile and low‐cost approach is demonstrated for the fabrication of high‐density sub‐1‐nm gaps from Au nanoparticle monolayers as reproducible surface‐enhanced Raman scattering (SERS) substrates. Au nanoparticles with larger diameters possess lower surface charge, thus the obtained large‐area nanoparticle monolayer generates a high‐density of sub‐1‐nm gaps. In addition, a remarkable SERS performance with a 10¹¹ magnitude for the Raman enhancement is achieved for 120 nm Au nanoparticle monolayers due to the dramatic increase in the electromagnetic field enhancement when the obtained gap is smaller than 0.5 nm. The Au nanoparticle monolayer is also transferred onto a stretchable PDMS substrate and the structural stability and reproducibility of the high‐density sub‐1‐nm gaps in Au monolayer films are illustrated. The resultant Au nanoparticle monolayer substrates with an increasing particle diameter exhibit tunable plasmonic properties, which control the plasmon‐enhanced photocatalytic efficiency for the dimerization of p‐aminothiophenol. The findings reported here offer a new opportunity for expanding the SERS application.     

Multiplex SERS Detection of Metabolic Alterations in Tumor Extracellular Media

The composition and intercellular interactions of tumor cells in the tissues dictate the biochemical and metabolic properties of the tumor microenvironment. The metabolic rewiring has a profound impact on the properties of the microenvironment, to an extent that monitoring such perturbations could harbor diagnostic and therapeutic relevance. A growing interest in these phenomena has inspired the development of novel technologies with sufficient sensitivity and resolution to monitor metabolic alterations in the tumor microenvironment. In this context, surface‐enhanced Raman scattering (SERS) can be used for the label‐free detection and imaging of diverse molecules of interest among extracellular components. Herein, the application of nanostructured plasmonic substrates comprising Au nanoparticles, self‐assembled as ordered superlattices, to the precise SERS detection of selected tumor metabolites, is presented. The potential of this technology is first demonstrated through the analysis of kynurenine, a secreted immunomodulatory derivative of the tumor metabolism and the related molecules tryptophan and purine derivatives. SERS facilitates the unambiguous identification of trace metabolites and allows the multiplex detection of their characteristic fingerprints under different conditions. Finally, the effective plasmonic SERS substrate is combined with a hydrogel‐based three‐dimensional cancer model, which recreates the tumor microenvironment, for the real‐time imaging of metabolite alterations and cytotoxic effects on tumor cells.     

纳米结构分子吸附引起的表面增强拉曼散射研究

利用模板印刷技术,制备了具有不同局域表面等离子体共振(LSPR)峰的Au纳米空心半球壳结构,并以4-巯基苯胺(4-ATP)为探针分子研究了纳米结构表面吸附分子对表面增强拉曼散射(SERS)强度的影响。结果表明,当纳米结构的LSPR峰位处于激发光波长的短波长或"马鞍型"位置时,SERS强度随吸附分子数的增加而增大;当处于长波长位置时,SERS强度呈现先增大后减小的趋势。利用分子吸附理论和纳米结构表面局域场强度变化,对此现象进行了解释。