苯硫酚吸附在新型Ag-Au合金纳米粒子上的表面增强拉曼光谱研究

以柠檬酸钠同时还原制备的Ag-Au合金纳米粒子为种子,用盐酸羟胺进一步使其生长得到粒径为40～60 nm的新型Ag-Au合金纳米粒子,采用UV-Vis光谱和TEM对纳米种子和再生长后的纳米粒子分别进行表征。两种粒子的UV-Vis光谱均只观察到一个等离子体共振峰,其频率随金的摩尔分数(x_Au)增加而红移,且TEM图像表明这两种粒子的颜色均一,因此判断这两种粒子均为合金结构。以苯硫酚为探针分子,研究了该新型合金纳米粒子的表面增强拉曼光谱(SERS),结果表明吸附了苯硫酚的合金纳米粒子的紫外最大吸收峰红移,并在近红外区出现聚集体的吸收峰。在632.8 nm波长激发下,由于表面等离子体共振效应Au上的SERS信号最强,而合金纳米粒子上的SERS信号随x_Au增大而增强。     

光谱分析法应用于咖啡成分的测定和咖啡种类的鉴别

应用光谱分析法测定现磨咖啡、速溶咖啡和菊苣咖啡的成分。通过电感耦合等离子体发射光谱(ICP-ES)测定咖啡样品的矿物质元素。分别采用紫外(UV)和傅里叶红外(FTIR)光谱法测定咖啡因和有机物的含量,草酸的测定需要采用氧化还原滴定法来完成。基于咖啡因、草酸和矿物质的测定,分析现磨咖啡、速溶咖啡和菊苣咖啡的差异。实验表明,咖啡因在速溶咖啡中的含量比现磨咖啡的要高出2～3倍;草酸在速溶咖啡中的含量明显高于现磨咖啡;矿物质元素Mg,P,Zn在现磨咖啡中的含量比速溶咖啡的要低,而Cu的含量则比速溶咖啡高出好几倍;菊苣咖啡中的矿物质含量总体上比速溶咖啡的要低。此外,我们在不同种类的咖啡中测定Ti的含量,在菊苣咖啡中检测到Cu,Ti,Zn元素。作为一种快速检测技术,FTIR光谱可以用于鉴别现磨、速溶和菊苣咖啡,并能够检验咖啡因和草酸的存在。     

憎水性金属纳米粒子及其LB膜的制备与光谱表征

用油酸钠和十四烷基硫醇作为稳定剂,制备了高度单分散的疏水性银和金纳米溶胶。考察了单粒子层的π－Ａ曲线并建造了纳米粒子的ＬＢ膜。通过紫外可见光谱讨论了纳米粒子的分散状态,由红外光谱结果讨论了纳米粒子表面有机吸附层的状态。     

Steady-State Spectroscopic and Fluorescence Lifetime Measurements of New Two-Photon Absorbing Fluorene Derivatives

Steady-state excitation anisotropy, lifetimes, and time-resolved emission spectra of new 2-photon absorbing fluorene derivatives were measured in aprotic solvents at room temperature. Excitation anisotropy spectra in viscous silicon oil allowed the determination of the spectral position of three electronic transitions S₀ S₁, S₀ S₂, S₀ S₃ (S_i, i = 1, 2, 3 are the singlet electronic states) and the angles ( 30°) between absorption S₀ S₁ and emission S₁ S₀ dipole moments for the first electronic transition. Solvate relaxation processes in the first excited state of the investigated fluorene molecules affect the lifetimes of these states, ₁, so that experimental values of ₁ do not correspond to those calculated by Strickler and Berg theory. The influence of the molecular concentration on the fluorescence quantum yields and ₁ have been investigated.     

Investigation of the influence of silver and tin on the luminescence of trivalent europium ions in glass

Europium-doped aluminophosphate glasses prepared by the melt-quenching technique have been studied by photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). The effects of silver and tin doping, and of further thermal processing on Eu³⁺ ions luminescence have been assessed. For the glass system containing only europium, Eu³⁺ PL observed under UV excitation is suggested to occur through energy transfer from the excited glass host. After silver and tin doping, an enhanced UV excited Eu³⁺ PL has been indicated to occur essentially due to radiative energy transfer from isolated Ag⁺ ions and/or two fold-coordinated Sn centers. Since thermal processing of the material leads to a quenching effect on Eu³⁺ PL and Ag nanoparticles (NPs) formation due to reduction of silver ions by tin, XPS was employed in order to investigate the possibility for Eu³⁺→Eu²⁺ reduction during HT as a potential source of the PL decrease. The data points towards Ag NPs as main responsible for the observed weakening of Eu³⁺ PL.     

基于差分反射光谱的真空环境有机薄膜生长在线监测方法

有机薄膜器件是微电子和光电子领域的重点研究方向。薄膜制备过程的在线监测作为研究成膜机理和优化工艺参数最直接的测量手段,对薄膜器件的高质量制备具有重要意义。为实现真空环境有机薄膜制备过程的实时在线监测,提出了一种基于差分反射光谱术的高精度测量方法。采用离轴抛物面反射镜、光学平板和光纤等基本光学元器件构建紧凑型光路系统,运用差分算法分析光谱信号,具有较高的测量性能。测试了不同实验环境下光谱信号的波动,得出在控温条件下,系统的长时间测量重复性优于2‰。还研究了并五苯分子通过分子束外延制膜法在Au基底成膜初始阶段的生长过程。通过与膜厚仪和原子力显微镜测试结果比对,光谱信号精确反映出超薄膜在生长中引起的细微光学演变,其测量精度优于亚单分子层。实验结果表明,该差分反射光谱测量系统具有宽光谱(300～820 nm)、高稳定性(重复性优于2×10-3)、高测量精度(亚单分子层)等特点,并有效地抑制了光路装配误差、光学器件缺陷和环境干扰等对光信号的影响,作为一种高精度表面表征方法,适合于薄膜制备过程的实时在线监测。     

X射线光谱技术在生物与生态环境中的应用进展

环境样品中元素的浓度、空间分布和赋存形态等是认识元素的生物功能和环境行为的关键。本文对近年来X射线光谱技术在生物与生态环境中的应用研究进展进行了评述,发现X射线荧光光谱技术可以提供活体植物中元素迁移与分布的定量数据,且微区X射线荧光光谱和X射线吸收谱技术的联用可深入认识生物与元素的相互作用,尤其是生物对元素的吸收、转运、贮存和细胞解毒机制,同时也能够揭示典型环境样品中元素的来源、演化和归趋等环境行为。然而,由于生物和环境样品基质的复杂性和多样性,仍存在一些技术难点与挑战,如X射线荧光自吸收效应的克服、低丰度(5%～10%)的元素形态的准确鉴定,以及对活体细胞中短暂的元素氧化还原反应的捕捉等。     

Spectroscopic analyses of an ancient silver fragment of the reliquary bust of St. Leo

A fragment of the silver reliquary bust of St. Leo, made in Messina, Italy, in the last of 1739 and now preserved in the church of SS. Savior of Africo Nuovo, Reggio Calabria, Italy, was investigated with spectroscopic techniques (scanning electron microscopy (SEM)+energy-dispersive X-ray (EDX), X-ray diffraction (XRD)) in order to analyze the composition of the sample in terms of elements and compounds. EDX analysis employs an electron beam that interacts with the sample, leading to the emission of characteristic X-rays as secondary radiation. In the XRD analysis, a Cu Kα X-ray radiation is detected by a Si(Li) solid-state detector after the interaction with the sample. The chemical composition of the bulk allowed to identify the constituting metal alloy, while the detection of surface elements and compounds, closely related to the sample preservation, was useful in order to suggest to restorators the best interventions to minimize the conservation problems that could affect the durability of the precious artefact.     

Edge Plasma Biasing Experiments on the CASTOR Tokamak: Spectroscopic Investigation and Microwave Measurements

The effects of edge plasma biasing have been recently investigated by different spectroscopic diagnostics on the CASTOR tokamak. Measurements in visible, VUV and XUV ranges complement the knowledge of processes during a biasing phase, and confirm the occurrence of several types of plasma biasing regimes — so called radiating regime, non-radiating regime, and reduced H regime. The use of edge plasma biasing to study the possibility of Electron Bernstein Wave conversion has been demonstrated.     

太阳光谱法差分光学吸收光谱(DOAS)技术测量新疆二氧化氮柱体密度(英文)

用太阳光谱法测量得到了中国新疆(38.4°-48.7°N,75.0°-89.5°E)地区以及其它一些大城市如北京(39.99°N,116.30°E)、成都(30.63°N,104.09°E)、厦门(24.44°N,118.10°E)和香港(22.34°N,114.17°E)的NO2柱体密度。新疆NO2的垂直柱体密度介于7.5×1015(卡拉库勒湖,38.44°N,75.05°E)和1.41×1017molecules/cm2(乌鲁木齐,43.81°E,87.60°E)之间。北京、成都、香港和厦门的NO2垂直柱体密度分别为8.50×1016、7.42×1016、5.62×1016和4.92×1016molecules/cm2。将新疆NO2污染程度与中国其它几个主要城市进行对比,可为反映中国西部地区工业快速发展提供参照。     

XPS characterization of the surface immobilization of antibacterial furanones

Brominated furanones have attracted recent interest as antibacterial compounds. To utilize them as protective coatings in biomedical device applications, they must be covalently immobilized onto solid surfaces; however, interfacial coupling protocols developed for other biomolecules are not applicable to furanones. An azide reaction scheme has enabled covalent immobilization onto fluorinated ethylene propylene copolymer but its chemistry is less predictable, requiring detailed characterization by XPS and tapping mode AFM after each step of the immobilization sequence. XPS curve fitting resolved components in the C 1s, N 1s and Br 3d regions. Angle dependent XPS was used to assess the depth distributions and layer thicknesses. The results indicated successful covalent immobilization of furanones; however, side reactions occurred. In addition to the expected CBr, a contribution from bromine ion (Br⁻) was detected, indicating that photo-degradation of furanones took place during UV illumination, and this reaction was found to increase with illumination time. The Br⁻ was removed by washing with water, whereas the CBr signal from immobilized furanone remained. Spectroscopic characterization will assist in elucidating the structure of furanone coatings, understanding their mode of action when covalently immobilized on surfaces, and rationally designing and optimizing an effective antibacterial coating for biomedical applications.     

Spectroscopic characterization of Ni films on sub-10-nm silica layers: Thermal metamorphosis and chemical bonding

The thermal evolution in the chemical and physical characteristics of the Ni film of thickness 1-50 nm deposited on silica of thickness less than 10 nm was studied. The chemical composition of silica affected the thermal behavior of the Ni overlayer substantially. Nickel deposited on native oxide may diffuse downward into native oxide during annealing and was oxidized. It mainly produced Ni₃O₂ and silicides below 150 °C. Increasing the temperature to 300 °C caused further oxidation of Ni to yield NiO. The sub-10-nm silicon dioxide layer, on the other hand, can inhibit the diffusion of Ni atoms downward when the Ni-deposited sample was annealed. Instead, these atoms aggregated into small particles on the surface at elevated temperatures, causing the substrate to be exposed. The size of the particles produced can be controlled, as it increased almost linearly with the thickness of the Ni film deposited in the low thickness regime. The thinner Ni films yielded smaller, round nanoparticles with better dispersity. The particles formed were strongly adhered to the silicon dioxide surface. The bulk of the particles formed was mainly metallic. Exposing to the air of the Ni particles formed on silicon dioxide mainly produces Ni₂O₃ on the particles.     

X-ray diffraction studies on crystallite size evolution of CoFe2O4 nanoparticles prepared using mechanical alloying and sintering

Nanosized cobalt ferrite spinel particles have been prepared by using mechanically alloyed nanoparticles. The effects of various preparation parameters on the crystallite size of cobalt ferrite which includes milling time; ball-to powder weight ratio (BPR) and sintering temperature, were studied using X-ray diffractometer (XRD). Scherrer's equation was used to study the crystallite size evolution of the as-prepared materials. The results of the as-milled sample revealed that both milling time and BPR plays a role in determining the crystallite size of the milled powder. However, where sintering is involved, the sintering temperature results in grain growth, and thus plays a dominant role in determining the final crystallite size of the samples sintered at higher temperature (above 900 °C). From the vibrating-sample magnetometer (VSM) measurement it was observed that the coercivity of the as-milled samples without sintering is almost negligible, which is a type characteristic of superparamagnetic material. However, for the sintered samples, the saturation increases while coercivity decreases with increases sintering temperature.     

介质阻挡放电氢等离子体中氢原子浓度的光谱诊断

在化学气相沉积功能材料等离子体刻蚀及表面处理等过程中, 氢原子起着非常重要的作用。文章详细论述了利用发射光谱技术诊断氢原子的基本原理,以氩气作为内标对介质阻挡放电氢等离子体中的氢原子浓度进行了定量的诊断,研究了氢原子浓度、氢分子解离率随气压的变化规律。发现在0.32到5.1 kPa气压范围内,氢分子的解离率由5.2%下降到0.089%,相应的氢原子浓度由4.9×1015·cm-3下降到1.3×1015·cm-3。文章还研究了氢Balmer系以及氩(750.4 nm)谱线的发射强度随气压、放电电压、频率等放电参数的变化规律。     

Soft X-ray microscopy and spectroscopy at the molecular environmental science beamline at the Advanced Light Source

We present examples of the application of synchrotron-based spectroscopies and microscopies to environmentally relevant samples. The experiments were performed at the molecular environmental science beamline (11.0.2) at the Advanced Light Source, Lawrence Berkeley National Laboratory. Examples range from the study of water monolayers on Pt(1 1 1) single crystal surfaces using X-ray emission spectroscopy and the examination of alkali halide solution/water vapor interfaces using ambient pressure photoemission spectroscopy, to the investigation of actinides, river water biofilms, Al-containing colloids and mineral–bacteria suspensions using scanning transmission X-ray spectromicroscopy. The results of our experiments show that spectroscopy and microscopy in the soft X-ray energy range are excellent tools for the investigation of environmentally relevant samples under realistic conditions, i.e., with water or water vapor present at ambient temperature.     

Vis-NIR光谱模式识别结合SG平滑用于转基因甘蔗育种筛查

以Savitzky-Golay (SG)平滑筛选,主成分分析(PCA)分别结合有监督的线性判别分析(LDA)、无监督的系统聚类分析(HCA),应用于转基因甘蔗育种筛查的可见-近红外(Vis-NIR)无损检测。提出兼顾随机性、稳定性的定标、预测、检验框架;取田间种植处于伸长期甘蔗叶样品456个,具有Bt基因和Bar基因的转基因样品(阳)306个,非转基因样品(阴)150个;随机选取156个为检验集(阴性50、阳性106),余下为建模集(阴性100、阳性200,共300),建模集再随机划分为定标集(阴性50、阳性100,共150)、预测集(阴性50、阳性100,共150)共50次;扩充SG平滑点数,同时删除绝对值偏小的高阶导数模式,共264个平滑模式用于模型筛选;采用前3个主成分两两组合,再根据模型效果选出最优主成分组合;基于所有定标、预测集划分和SG平滑模式,建立SG-PCA-LDA和SG-PCA-HCA模型,根据平均预测效果优选参数,使模型具有稳定性;最后用检验集进行模型检验。经SG平滑后,PCA-LDA和PCA-HCA的建模精度、稳定性均显著改善;最优SG-PCA-LDA模型阳性、阴性样品检验识别率分别达到94.3%和96.0%;最优SG-PCA-HCA模型阳性、阴性样品检验识别率分别达到92.5%和98.0%。结果表明：Vis-NIR光谱模式识别结合SG平滑可用于转基因甘蔗叶的准确识别,提供了一种简便的转基因甘蔗育种筛查方法。     

Molecular recognition of chromophore molecules to amine terminated surfaces

We report the design and characterization of quartz surfaces that can bind to three retinal based chromophores. The amine terminated surfaces were engineered in order to mimic the environment of the opsin protein that accommodates binding of chromophore molecules in the human eye. Each surface coupling step was characterized by water contact angle measurements, ellipsometry, atomic force microscopy, X-ray photoelectron spectroscopy, and transmission infrared spectroscopy. The spectroscopic techniques confirmed that the three chromophore molecules can bind to the surface using a Schiff base mode. Our data suggests that the availability of the amine groups on the surface is critical in the accommodation of the binding of different chromophores.     

Spectroscopic investigation of arsenate and selenate incorporation into hydroxylapatite

The mechanism(s) of arsenate and selenate incorporation into hydroxylapatite (HAP) using extended X-ray absorption fine structure (EXAFS) spectroscopy was investigated for As- and Se-doped HAP samples with concentrations between 200 and 2500 ppm. EXAFS data on As and Se K-edges have shown similar local coordination environments and are similar to that of P in HAP, suggesting the substitution of arsenate or selenate tetrahedra on the phosphate sites. EXAFS best-fitting for As-doped samples shows that the first shell is fitted with approximately 4 O atoms at 1.68 Å, showing As(V) in tetrahedral coordination, and Se K-edge EXAFS data are characterized by the backscattering contributions an oxygen shell at 1.2 Å in the Fourier transform, which can be fit with 4 O atoms at 1.65 ± 0.01 Å. This is characteristic of Se–O distances in SeO₄ tetrahedron. These findings suggest that arsenate and selenate substitute for phosphate groups with local distortions during the incorporation of these metals into the structure of HAP.