应用于低折射率样品检测的SERS活性液芯光纤

用纳米组装方法在空心光纤内壁修饰SERS活性基底构成内壁具有表面增强拉曼光谱活性层的液芯光纤。激发光由光纤壁横截面入射,并在光纤壁中传播。由于光纤壁的折射率大于检测样品溶液的折射率,使得激发光在光纤壁中发生全反射,并在消逝场下穿透修饰层,激发样品拉曼散射。本方法融合了表面增强拉曼光谱技术与液芯光纤技术的优势,可成为应用于低折射样品溶液体系检测的又一手段。     

锥形光纤SERS探针的工艺优化和拉曼光谱增强实验

采用化学腐蚀法制备锥形光纤,采用溶液化学沉积法将银纳米颗粒修饰到锥形光纤端面,形成光纤表面增强拉曼散射(SERS)探针。改变反应温度、沉积时间、硝酸银溶液浓度等关键参数,优化了光纤SERS探针的制备工艺。以R6G为探针分子,对不同工艺条件制备的光纤SERS探针进行拉曼测试实验。结果表明:在室温下,当沉积时间为120s、硝酸银溶液浓度为0.1mol/L时,最优的增强因子约为10~(10),此时光纤SERS探针的拉曼检测性能最好。对应10组样品的银纳米颗粒的直径和面积覆盖率,利用FDTD Solutions进行仿真建模分析,计算得到了拉曼增强因子理论值为10~7~10~8。     

双金属锥形光纤表面增强拉曼散射探针拉曼增强特性

为了提高金属纳米粒子在光纤表面的富集密度,同时提高光纤表面增强拉曼散射(SERS)复合结构拉曼增强特性的稳定性,提出一种双金属(金和银)锥形光纤SERS探针结构。首先,采用化学还原法制备出形貌均一的金银纳米粒子;然后,采用光诱导的方法实现双金属在锥形光纤上的富集。制备的光纤SERS探针表现出良好的实验效果：对罗丹明6G(R6G)检测到的最低浓度低至10^-10 mol/L;增强因子为2.07×10⁸;相较于单金属银光纤SERS探针,双金属样品的稳定性提高了7倍(96 h后)。     

大孔柚子型微结构光纤探针的表面增强拉曼散射性能研究

随着光纤制备工艺以及纳米材料制备技术的发展,光纤探针已成为一种新型的表面增强拉曼散射(SERS)基底,通过在普通单模光纤或多模光纤上制备不同的结构并修饰相应的纳米材料,可以得到多种类型的光纤表面增强拉曼散射探针,并实现较好的检测效果。但受限于光纤本身的结构,普通光纤仅能利用端面或侧表面提供拉曼检测的“热点”区域,限制了其SERS性能的进一步提高。因此制备了大孔柚子型微结构光纤(MSF)表面增强拉曼散射(SERS)探针,其中大孔柚子型MSF SERS探针结构通过一段阶跃多模光纤与柚子型微结构光纤熔接制得。实验分别对自制的纳米银溶胶基底以及大孔柚子型MSF SERS探针的SERS性能进行检测。采用溶胶自组装法制备负载银纳米颗粒的MSF SERS探针,通过控制自组装时间制备不同光纤SERS探针(Ag/MSF-x,其中x为自组装时间,分别为15、 30、 45、 60 min)。采用溶液检测方法,利用Ag/MSF-x探针对10^-3 mol·L^-1的亚甲基蓝(MB)探针分子进行检测,通过比较相同条件下的增强效果筛选得到Ag/MSF-45探针。为进一步检...     

贵金属纳米结构为敏感层的锥形光纤探针及其SERS活性

表面等离激元纳米结构与便携式光纤拉曼系统相结合,在液体样品和生物活体组织的快速、实时监测上有较好的应用前景。其核心技术是将具有表面增强拉曼散射(SERS)活性的贵金属纳米结构耦合到光纤探针表面。本文基于共价键结合原理,将3-巯丙基三甲氧基硅烷通过与锥形光纤探针表面的硅羟基形成共价键修饰在光纤上;同时,硅烷偶联剂末端的巯基与金或银纳米结构形成Au-S或Ag-S共价键,将金纳米粒子和银纳米立方体牢牢吸附到光纤探针表面。这种SERS光纤探针具有很高的稳定性(SERS信号相对标准偏差低于3%),对农残甲基对硫磷的敏感度达到10纳摩尔,对污染物的远程、便携式在线检测具有重要意义。     

基于空芯微结构光纤拉曼探针的实验研究

表面增强拉曼散射(SERS)技术可有效增强样品分子的拉曼信号,对生物分子检测具有较高的灵敏性,因此在生化方面有着许多潜在的应用.而将空芯微结构光纤与SERS技术相结合不仅能够远端实时、分布式地检测,同时还可以增加光场与待测物的有效作用面积,减少传统光纤探针无法避免的石英背景信号等问题.本文基于空芯微结构光纤进行SERS探针的制备及性能测试研究,利用真空物理溅射法在空芯光纤内镀纳米Ag膜,从而制备成SERS探针,通过实验检测不同浓度的罗丹明6G (R6G)酒精溶液的拉曼信号.结果表明,在探针的近端正面成功探测到了浓度低至10~(-9)mol/L的R6G拉曼信号,在探针的远端反面探测到的浓度可小于10~(-6)mol/L.该实验结果为研究高灵敏度的SERS探针提供了一种新的手段.     

一种新型表面增强拉曼活性基底的制备及表征

研究了一种新的表面增强拉曼活性银基底的制备方法,采用银增强剂和引发剂的混合溶液处理全铝表面制备了银基底,利用扫描电子显微镜分析了基底的表面形态和结构,测定结晶紫分子在基底表面的拉曼光谱.结果表明,这种基底具有很强的表面增强拉曼散射效应(SERS)活性和稳定性.     

三种不同银纳米粒子SERS基底比较研究

表面增强拉曼光谱(SERSp)技术是一种新兴的分析检测技术,由于其对样品分析灵敏度高、检测时间短以及样品所需量小等优点,近年来该技术已在生物医学,化学等领域得到广泛的应用,同时表面增强拉曼散射(SERS)基底的制备已成为该领域的研究热点。本文主要对三种以银纳米粒子(AgNPs)的SERS效应为基质的拉曼活性基底:毛细管-AgNPs,二氧化钛-AgNPs和滤纸-AgNPs进行比较研究。首先分别用三种基底对罗丹明6G(R6G)分子进行拉曼光谱采集及分析,找出三种SERS基底相应的最佳制备条件。最后用这三种最佳条件下制备的SERS基底对同一个健康人血清进行拉曼光谱检测,并对结果进行分析比较。初步结果:三种SERS基底都是可靠的和实用的;二氧化钛-AgNPs基底灵敏度相对较高,但制备过程较复杂;滤纸-AgNPs基底灵敏度其次;毛细管-AgNPs基底及滤纸-AgNPs基底的制备均较为简单。因此,从实用角度考虑,滤纸-AgNPs基底比较适合血清的表面增强拉曼光谱检测与分析。     

打印技术制备表面增强拉曼散射活性基底的研究进展

表面增强拉曼散射(SERS)是一种先进的表面分析技术,可以极大提高吸附在金属表面或附近分子的拉曼散射信号。SERS技术由于其快速准确、灵敏度高、选择性好、样品制备要求低等特点,成为当前的研究热点,在化学、食品、生物、医疗等领域展现出重要的应用前景。而利用SERS技术作为一种常规分析和诊断工具面临的一个主要挑战是如何制备均匀、可重复、稳定的活性基底。打印技术操作简单、效率高、成本低,有助于设计等离激元纳米结构。通过优化“热点”增强电磁场,获得重复性好、稳定性高、增强能力强的SERS活性基底。近年来,印刷技术逐渐被应用于SERS基底的制备。主要综述了制备SERS基底的几种常用印刷技术,包括喷墨印刷、凹版印刷、丝网印刷等。分析了衬底表面润湿性、干燥温度、油墨粘度、表面张力、溶剂等因素对SERS性能的影响。总结了印刷技术制备SERS基底的研究进展,并对其潜在应用和未来发展作了展望。     

纳米银溶胶的制备及利用其SERS效应检测BPA的研究

制备了银溶胶作为表面增强活性基底,以此为基础详细研究了BPA的表面增强拉曼光谱(SERS)。研究了促凝剂氯化钠的加入对增强效果的影响。实验结果表明,当BPA乙醇溶液的浓度低至10-7g/mL时,依然可以得到明显的SERS信号。此方法操作简便快捷,无需对样品进行预处理,在BPA的快速检测方面具有很大应用潜力。     

全正色散多波长被动锁模耗散孤子掺镱光纤激光器

报道了一种带有周期性双折射光纤滤波器的全正色散多波长被动锁模耗散孤子掺镱光纤激光器. 通过数值模拟发现加入滤波器后激光器能输出多波长耗散孤子脉冲, 调节滤波器带宽大小可以得到不同波长个数和波长间隔的多波长锁模耗散孤子脉冲. 在激光器产生的四波长和五波长耗散孤子脉冲中观察到了耗散孤子分子, 并且通过调节滤波器参数和饱和功率可以改变多波长脉冲中耗散孤子分子的个数和波长. 这是在被动锁模光纤激光器中首次实现包含有耗散孤子分子的多波长脉冲. 另外还在实验上实现了全正色散双波长被动锁模耗散孤子的产生. 关键词： 全正色散 耗散孤子 多波长脉冲 孤子分子     

The influence of hydrochloric acid treatment and temperature on the electro-physical properties of super-thin basalt fibers

Electro-physical parameters of super-thin basalt fiber (STBF) from Armenian basalt rocks are measured before and after hydrochloric acid treatment. It is shown that specific resistance and dielectric parameters of super-thin basalt fiber change essentially after hydrochloric acid treatment. The temperature dependence of these parameters was studied too. The probable cause of the change is an increase in the total amount of pores and modification of the share of pores of various sizes in STBF, followed by an increase of absorption of water molecules from the ambient medium. The results (in both alternating and direct electric fields) are interpreted within the framework of the dipole-relaxation mechanism of the polarization of water molecules in STBF pores.     

液芯光纤共振拉曼光谱法检测水中生物分子研究

拉曼光谱是研究水中生物分子重要的有效方法之一,然而由于拉曼散射截面小,特别是水分子的电子激发态能级高,因此水中生物分子的拉曼光谱测量甚为困难。将液芯光纤技术和共振拉曼技术结合起来,可大幅度提高拉曼光谱强度。实验中用可以获得最大的共振拉曼光谱强度的514.5 nm Ar+离子激光激发,分别用石英和Teflon液芯光纤对水中β-胡萝卜素生物分子进行了痕量检测研究。结果表明应用石英液芯光纤和Teflon液芯光纤可分别检测浓度为10-7～10-9mol·L-1和10-9～10-10mol·L-1的β-胡萝卜素。     

Transcrystalline interphases in natural fiber-PP composites: effect of coupling agent

The interest in lignocellulosic fiber composites has been growing in recent years because of their high specific properties. In this work, a new technique was used to prepare specimen to observe the transcrystalline zones in kenaf fiber-polypropylene composites. A maleated polypropylene (MAPP) coupling agent was used to improve the stress-transfer efficiency in the composites. Transcrystallinity was observed for both the uncoupled and coupled composites, although the rate of growth was higher for the coupled composites. Dynamic mechanical spectroscopy was used to observe the relaxations of the composites. The peak temperature of the β-relaxation, associated with the glass-rubber transition of the amorphous molecules, of the coupled composites was higher than that of the uncoupled composites. Restricted molecular mobility due to covalent interactions between the MAPP and the lignocellulosic surface may account for the shift to higher temperatures. It appears that during compounding the extractives sheared from the fiber surface is an important factor in determining the β-relaxation of these composites. The intensities of the α-transition, related to molecular mobility associated with the presence of crystals, is proportional to the fiber volume fraction. Thus it is possible that the molecules responsible for the α-transition are predominantly in the transcrystalline zone. These 'rigid' amorphous molecules in the transcrystalline zone do play a role in composite behavior and need to be considered when tailoring interphases.     

Experimental Studies on the Response of the Fiber Optic Evanescent Field Absorption Sensor

In the present study the response of the fiber optic evanescent field absorption sensor has been analyzed experimentally. The dependence of evanescent absorbance on sample (dye) concentration has been found to be nonlinear, in contradiction to theoretical predictions. The amount of nonlinearity as well as evanescent absorbance has been found to depend on the pH of the sample. As the pH decreases, the amount of nonlinearity and evanescent absorbance decrease. It has been shown that the nonlinearity and high evanescent absorbance at high pH value occur because of the adsorption of the positively charged dye molecules on the surface of the silica core of the plastic-clad silica (PCS) fiber, which is generally used for the sensor. A linear response has been obtained at pH close to 2.0, at which the presence of a tremendous amount of H ions in the sample restricts the adsorption of the dye molecules. The following empirical relation has been found to fit the experimental data: gamma 1.1C 1.6(pH)32C 1 3, where gamma is the evanescent absorption coefficient and C is the concentration of the dye. The first term is due to the simple Beer's law while the second term is the contribution of the pH dependent dye adsorption. In addition, we have found that the increase in core diameter increases the contribution of adsorption.     

Impact of slow gain dynamics on soliton molecules in mode-locked fiber lasers

We theoretically demonstrate and experimentally confirm the major influence of gain dynamics on soliton molecules that self-assemble in mode-locked lasers. Both slow gain recovery and depletion play a pivotal role in the formation of chirped soliton molecules characterized by an increasing separation from leading to trailing pulses. These chirped molecules actually consist of many pulses and may be termed macromolecules. They are experimentally observed in a fiber laser and numerically modeled by an approach that properly includes the slow gain dynamics. Furthermore, it is shown that these processes stabilize soliton trains in fiber lasers by inhibiting internal oscillations.     

Micro double tapered optical fiber sensors based on the evanescent field-effect and surface modification

A double tapered optical fiber sensor based on evanescent field-effect and surface modification technology was introduced in this work. Whether the liquid and gas molecules had polarities or not, they all could be detected by the sensors modified in different silane coupling agents. At the same time, the sensing characters of the single mode optical fiber with three different tapering lengths were researched, and it came to a conclusion that the optical fiber sensor had stronger evanescent field effect and higher sensitivity when length of tapered fiber was 30 mm. The functionalized tapered fibers modified by 3-aminopropyltrimethoxy silane (APTES) or 3-methylpropenylacyloxy propyltrimethoxy silane (MPAPTES), were employed to detect the polar or nonpolar molecules which had corresponding features. Further, the results of quantitative tests showed that the fiber optic sensor was sensitive to the change of the ethanol concentration and the characteristic peaks of the absorption power spectra could reach to 3–5 dB.     

鲱精DNA纤维水合状态的振动谱特征

利用拉曼散射光谱测试技术，对不同温度处理后获得的各种相对湿度下的鲱精ＤＮＡ纤维进行脱氧核苷Ｃ—Ｈ振动与结合水Ｏ—Ｈ振动行为分析，以揭示其中结合水的数量特征。结果表明，运用２５９２６×Ｉ２９６４／Ｉ３０２４新指标所获数据与文献报道的小牛胸腺ＤＮＡ水合状态拉曼数据不同，但与小牛胸腺ＤＮＡ、鲑精ＤＮＡ的红外、Ｘ射线衍射、重量分析及差示扫描量热分析所得数据相吻合，证明拉曼分析公式的修订是成功的。鲱精ＤＮＡ纤维应与上述二种ＤＮＡ纤维具有同样的水合状态，每核苷酸对含有９～１４个结合水分子。     

Random-hole optical fiber evanescent-wave gas sensing

Research on development of optical gas sensors based on evanescent-wave absorption in random-hole optical fibers is described. A process to produce random-hole optical fibers was recently developed that uses a novel in situ bubble formation technique. Gas molecules that exhibit characteristic vibrational absorption lines in the near-IR region that correspond to the transmission window for silica optical fiber have been detected through the evanescent field of the guided mode in the pore region. The presence of the gas molecules in the holes of the fiber appears as a loss at wavelengths that are characteristic of the particular gas species present in the holes. An experimental setup was constructed with these holey fibers for detection of acetylene gas. The results clearly demonstrate the characteristic absorptions in the optical spectra that correspond to the narrow-line absorptions of the acetylene gas, and this represents what is to our knowledge the first report of random-hole fiber gas sensing in the literature.     

手征参数对光纤中模式特性的影响

对圆芯和包层都是手征介质的阶跃型手征光纤进行了解析求解，导出了模式特征方程，给出了手征光纤中模式场，光强和光功率分布的表达式。分别研究了纤芯和包层中的手征参数对模式特性的影响．。