From curdlan powder to the triple helix gel structure: an attenuated total reflection-infrared study of the gelation process

Infrared spectroscopy was used to probe the hydration and gelation of curdlan, a linear polysaccharide built from repeating units of (1-->3)-beta-D-glucose. The spectra have been recorded using a temperature-controlled attenuated total reflection (ATR) device. Thermal gelation of curdlan could therefore be followed in situ and in real time. The transformation of the low-set gel, mainly formed with single helices, into a high-set gel, associated with a triple helix structure, could be directly observed. The relative intensities and positions of characteristic absorption bands in the C-O region (1200-850 cm-1) were found to be representative of the gel structure, as they are believed to be sensitive to the helical conformation of the polymer chains. Infrared (IR) spectroscopy is shown to be a useful tool for rapid and efficient characterization of curdlan gels.     

In situ observation of absorption spectra and adsorbed species of methylene blue on indium-tin-oxide electrode by slab optical waveguide spectroscopy

In situ absorption spectra of methylene blue (MB) adsorbed on an indium-tin-oxide electrode were observed by slab optical waveguide (SOWG) spectroscopy. The absorption spectrum of the MB obtained by the SOWG spectroscopy coincided with that by conventional spectroscopy for the solution phase, and the MB existed as dimer at 0 V vs. Ag/AgCl. Upon the electrode potential of cathodic condition, the absorption spectra gradually changed showing the appearance of the monomeric species as well as the highly aggregated species of MB.     

Role of ZnO-CeO2 Nanostructures as a Photo-catalyst and Chemi-sensor

ZnO-CeO2 nanostructures were synthesized by simple and effcient low temperature method. The structure and morphology of the ZnO-CeO2 nanostructures were characterized by X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FESEM), which revealed elongated shaped CeO2 nanoparticles with diameters of 40-90 nm distributed on the surface of elongated ZnO nanostructures with diameters of 50-200 nm (edge-centre). Further the structure of the synthesized ZnO-CeO2 nanostructure was supported by Raman spectra and Fourier transform infrared spectroscopy (FTIR). UV-vis absorption spectrum was used to confirm the optical properties of the CeO2 doped ZnO nanostructures. Photo-catalytic activity of CeO2 doped ZnO nanostructure was evaluated by degradation of acridine orange and methylene blue which degraded 84.55% and 48.65% in 170 min, respectively. ZnO-CeO2 nanostructures also showed good sensitivity (0.8331 μA·cm-2·(mol/l)-1) in short response time (10 s) by applying to chemical sensing using ethanol as a target compound by I-V technique. These degradation and chemical sensing properties of ZnO-CeO2 nanostructures are of great importance for the application of ZnO-CeO2 system as a photo-catalyst and chemical sensor.     

二甲基硅油 C-Si 伸缩振动模式红外光谱研究

在303~393 K温度范围内,采用变温傅里叶变换衰减全反射红外光谱技术(ATR-FTIR)研究了二甲基硅油的一维红外光谱、二阶导数红外光谱、四阶导数红外光谱和去卷积红外光谱。实验发现,在1800~600 cm~(-1)范围内,二甲基硅油主要存在CH_3伸缩振动模式(νCH_3)、CH_3变形振动模式(δCH_3)、CH_3摇摆振动模式(ρCH_3)、Si-O伸缩振动模式(νSi-O)和Si-C伸缩振动式(νSi-C)等5种红外吸收模式,其中782 cm~(-1)和789 cm~(-1)处的红外吸收峰归属于二甲基硅油νSi-C。以二甲基硅油νSi-C为研究对象,进一步开展相关二维红外光谱的研究。结果发现,随着测定温度的升高,二甲基硅油νSi-C红外吸收强度的变化快慢顺序为:789 cm~(-1)782 cm~(-1)。本项研究拓展了ATR-FTIR技术在二甲基硅油热变性方面的研究范围。     

基于HTEMPO聚己内酯-聚苯乙烯嵌段共聚物的合成

以4-羟基-2,2,6,6-四甲基哌啶氮氧自由基(HTEMPO)为引发剂,采用配位-插入开环聚合(CROP)的方法引发ε-己内酯聚合,然后利用氮氧稳定自由基聚合(NMRP)调控苯乙烯聚合得到聚己内酯-聚苯乙烯嵌段共聚物(PCL-b-PS),并对此过程进行了动力学研究,结果表明,聚苯乙烯链段的分子量可控,符合活性聚合特征。通过GPC测定,共聚物的分子量分布范围是1.26~1.37。在FT-IR图上可以看到属于PCL-b-PS的特征峰,分别为3470 cm-1、1726 cm-1、1192cm-1、1047 cm-1、1600 cm-1、1493 cm-1和1453 cm-1处的羟基、羰基C-O-C的对称和不对称伸缩振动、苯环的骨架振动吸收峰。在1H-NMR谱图上,有δ=1.3~1.68、4.08的己内酯亚甲基氢的化学位移和6.30~7.20苯环上氢的化学位移。     

Applications of attenuated total reflection infrared spectroscopic imaging to pharmaceutical formulations

This paper demonstrates an approach to obtain chemical images of pharmaceutical tablets using attenuated total reflection infrared (ATR-IR) spectroscopy. FT-IR images with different fields of view and spatial resolution have been obtained using a combination of different ATR accessories. FT-IR imaging with the diamond ATR accessory and micro-ATR imaging technique have been compared. With the diamond ATR imaging accessory, compaction to a tablet can be performed and the chemical image measured in situ. It has been found that the diamond ATR imaging accessory gives information on the overall distribution of different components in a tablet while the micro-ATR imaging technique provides a closer look at the tablet with 4-microm spatial resolution. Low-concentration components down to 0.5% have been detected by the micro-ATR method. Both experimental and commercial systems are studied in this paper.     

Two-dimensional attenuated total reflection infrared and near-infrared correlation study of the structure of butyl alcohol/water mixtures

The effect of temperature on attenuated total reflection infrared (ATR-IR) and near-infrared (NIR) transmission spectra of pure butan-1-ol, butan-2-ol, 2-methyl-propan-1-ol, 2-methyl-propan-2-ol, and mixtures with a small water content (X(H2O) 相似文献   

Discrimination of the hard keratins animal horn and chelonian shell using attenuated total reflection-infrared spectroscopy

The ability to discriminate between objects manufactured from animal horn and chelonian (turtle, tortoise, or terrapin) shell is important from a cultural and archeological perspective such that it may allow conservators to determine the appropriate treatment and long-term care solution. It would also aid curators in identifying and cataloging items manufactured from these materials. Discrimination and classification is also a valuable tool for those involved in tracking the illegal trade in restricted materials of this nature. Attenuated total reflection infrared (ATR-IR) spectroscopy, using a single reflection diamond internal reflection element (IRE), coupled with discrimination analysis was used to analyze a total of thirty-nine samples (29 calibration samples, 10 validation samples). A discrimination analysis model was constructed using Mahalanobis distances to classify spectra into one of two classes. The model was then subsequently used to successfully classify all validation samples and correctly identify them as animal horn or chelonian shell based on second-derivative spectra of the amide I and II regions. This technique requires minimal to no sample preparation and may be used to nondestructively identify very small samples successfully without performing detailed secondary structural curve-fitting routines. This model should be a valuable resource to museums, conservators, and wildlife management programs for rapidly and reliably discriminating between animal horn and chelonian shell.     

Alginate ion adsorption on a TiO2 particle film and interactions of adsorbed alginate with calcium ions investigated by attenuated total reflection infrared (ATR-IR) spectroscopy

The adsorption of alginic acid on a TiO(2) particle film from aqueous solution was investigated by attenuated total reflection infrared (ATR-IR) spectroscopy. ATR-IR spectra recorded at different pHs confirmed that alginate adsorption to TiO(2) is favored at pH 3.0 and no significant adsorption occurs above pH 5.0. Upon adsorption the carboxylic acid groups of alginic acid are converted to the carboxylate form and bind to surface Ti(IV) ions via bridging bidentate structures. Spectral analyses of the carboxylic acid and carboxylate stretching vibrations indicated that about three in four -COOH groups are converted to -COO(-) groups as they bind coordinately to TiO(2). Additionally, the spectral data at pH 8.0 showed specific interactions of Ca(2+) ions with the free COO(-) groups of the polysaccharide backbone of adsorbed alginic acid.     

Multivariate curve resolution analysis on the multi-component water sorption process into a poly(2-methoxyethyl acrylate) film

In our previous study, sorption process of water into a biocompatible polymer film, poly(2-methoxyethyl acrylate) (PMEA) was monitored by time-resolved in situ attenuated total reflection infrared (ATR-IR) spectroscopy [S. Morita, et al., Langmuir 23, 3750 (2007)]. In the present study, noisy and heavily overlapped O-H stretching vibrational bands of diffusing water have been analyzed from the series spectra where the spectral shapes change irregularly with time. In spite of these complications, a powerful spectral analysis technique, multivariate curve resolution (MCR) by means of alternating least squares (ALS), yielded smooth and meaningful pure component spectra and detailed kinetic sorption profiles of each component, excluding noise. Ordinary smoothing techniques and Gaussian curve fitting would not achieve these significant results. The quantification of the kinetic parameters such as amplitudes (a) and relaxation time constants (tau) is significant for the systematic development of biocompatible materials and also for revealing the mechanisms of biocompatibility of a material. Moreover, the ratios of coefficients of each component at saturation corresponded well to the values obtained by Tanaka et al. measured by gravimetric analysis. This study is the first to report the detailed concentration profile of each water component whose sorption kinetics is discussed comprehensively.     

Study of adsorption behaviors of meso-tetrakis (4-N-Methylpyridyl) porphine p-Toluenesulfonate at indium-tin-oxide electrode/solution interface by in-situ internal reflection spectroscopy and cyclic voltammetry

In situ electrochemical-absorption spectra of meso-tetrakis (4-N-Methylpyridyl) porphine p-Toluenesulfonate (TMPyP) adsorbed on the surface of an ITO (indium-tin-oxide) electrode was observed by simultaneous measurements using cyclic voltammetry (CV) and internal reflection spectroscopy. The CV experiment was performed using ITO coated on glass as the working electrode, platinum wire as the counter electrode and silver/silver chloride (Ag/AgCl) electrode as the reference electrode. It was found that, in 1 M HCl and pH = 2 Britton-Robinson solutions, TMPyP were adsorbed on ITO as P(0)H₄²⁺ state and P(0)H₂ state, respectively. Moreover, when the potential was applied on the ITO electrode, the redox reactions of TMPyP in 1 M HCl were also different from those in pH = 2 Britton-Robinson solutions. The adsorption rate, desorption rate and equilibrium constants as well as the adsorption free energy of TMPyP were determined by fitting adsorption process between TMPyP and ITO using Langmuirian adsorption model. The effect of pH on the internal reflection spectra was also explored, in which it was shown that the increase of pH lead to the enhancement of the intensity of the internal reflection spectra and the blue shift of the peak position. With the increase of ionic strength of TMPyP solution, the intensity of the internal reflection spectra decreased.     

基于光腔衰荡光谱法的水汽线形强度测量

随着半导体芯片行业的迅速发展,对电子气体的要求也逐渐提高。半导体加工环境中的痕量水分会严重影响芯片的良率和可靠性。光腔衰荡光谱法是近年来发展的一种具有高灵敏度和准确性的痕量气体测量方法,线形强度是光谱法测量的重要参数。为测量痕量水分,建立了一套光腔衰荡光谱系统,测量了中心频率在 7171.10491cm-1和7177.6565cm-1的吸收光谱,通过HTP(Hartmann-Tran profile)线形拟合得到线形强度,测量结果的相对标准不确定度优于1.8%,与HITRAN、HITEMP和GEISA数据库比较,相对偏差小于6%。     

In situ raman spectral mapping study on the microscale fibers in blue coral (Heliopora coerulea) skeletons

The presence and localization of organic matrix associated with the aragonite phase in the fibers of blue coral Heliopora coerulea skeletons were studied by in situ microRaman mapping spectra, with a spatial resolution of ~0.3 μm. Spatial variations in the amounts and chemical compositions of the fibers were imaged. The results showed that the amide I and the α-helix of amide III were perpendicular to the c-axis of fibers' growth, whereas the β-turns/sheet of amide III was in the parallel conformation. Visible S-S and C-S bonds were consistent with the XANES results, which indicated the existence of organic sulfur in coral skeletons. Regular cyclic changes between aragonite and organic matrix refined a stepping growth mode of the fibers' biomineralization. An inorganic PO(4) bond was detected and exhibited the same concentration variation trends as the v(4) aragonite bands. Instead of providing an ocean P proxy on the subseasonal to centennial scale by LA-ICPMS, the possibility was raised of producing high resolution surface ocean phosphorus records on daily environmental variation via P/Ca variation cycles determined from Raman mapping data.     

己内酰胺在碳纤维表面的电聚合改性

采用循环伏安法,以己内酰胺为聚合单体对碳纤维进行电聚合改性。利用循环伏安特性曲线、傅里叶变换红外光谱、电脑伺服控制材料试验机、扫描电镜(SEM)研究了改性前后碳纤维及其复合材料表面结构与性能的变化。结果表明,当己内酰胺浓度为0.1 mol/L,循环次数为10次时,碳纤维的改性效果较佳;改性后的碳纤维在1650 cm~(-1)出现NH_2的变角振动吸收峰,1556 cm~(-1),1540 cm~(-1)出现羧酸COO反对称伸缩吸收峰;能谱测试发现碳纤维表面O含量增加了1.69%;复合材料的层间剪切强度(ILSS)由10.50 MPa增加到26.96 MPa,提高了156.70%;SEM图表明改性后碳纤维表面生成分散均匀的颗粒且具有一定厚度的聚合物涂层,与复合材料结合紧密且无拔出现象。     

硅氧树脂 Si-O 键伸缩振动模式ATR红外光谱研究

在303~393 K 温度范围内,采用变温傅里叶变换衰减全反射红外光谱(ATR-FTIR)技术分别测定硅氧树脂的一维红外光谱、二阶导数红外光谱和四阶导数红外光谱。研究发现,在1800~600 cm-1范围内,聚硅氧树脂主要存在着 CH 3伸缩振动模式(νCH3)、CH 3变形振动模式(δCH3)、CH 3摇摆振动模式(ρCH3)、Si-O 伸缩振动模式(νSi-O )和 Si-C 伸缩振动模式(νSi-C )。在1100~1000 cm-1范围内,以νSi-O 为研究对象,研究了温度对硅氧树脂分子结构的影响。实验发现,随着测定温度的升高,硅氧树脂νSi-O 的主要红外吸收频率出现了明显的红移现象。进一步研究了硅氧树脂νSi-O 的二维红外光谱,考查温度对于νSi-O 红外吸收强度的影响。研究发现,随着测定温度的升高,硅氧树脂νSi-O 红外吸收强度的变化快慢顺序为：1024 cm-1>1096 cm-1>1010 cm-1>1076 cm-1>1083 cm-1>1064 cm-1。本研究拓展了 ATR-FTIR 技术在硅氧树脂材料热变性方面的研究范围。     

Combined in situ atomic force microscopy-infrared-attenuated total reflection spectroscopy

The combination of atomic force microscopy (AFM) with infrared attenuated total reflection (IR-ATR) spectroscopy for simultaneous spectroscopic evanescent field absorption and scanning probe measurements is presented. The capabilities of the combined setup are demonstrated by in situ AFM imaging of the dissolution process of urea in a cyclohexane/butanol solution with nanometer topographical resolution, while simultaneously recording the correlated bulk spectral changes by mid-infrared evanescent field absorption spectroscopy. Hence, surface modification processes such as dissolution or deposition can be simultaneously monitored by AFM imaging and IR spectroscopy in liquid environments, which has not been demonstrated to date. This combined technique will in the future enable kinetic studies on physical, chemical, and biological processes at a wide variety of surfaces providing chemical specificity via IR spectroscopy in addition to high-resolution imaging via AFM.     

Determination of the weight percentage gain and of the acetyl group content of acetylated wood by means of different infrared spectroscopic methods

The weight percentage gain (WPG) and the acetyl group content of wood due to acetylation with acetic anhydride have been analyzed by means of Fourier transform infrared spectroscopy (FTIR) and near-infrared spectroscopy (NIR). Band height ratios (BHR) (1240/1030 (1230/1030) and 1745/1030 (1740/1030)) of the bands at 1745 (1740), 1240 (1230), and 1030 cm-1 were calculated from FTIR-KBr and FTIR-ATR (attenuated total reflection) spectra. The good linear correlation with a coefficient of determination of about 0.94 over a range from 0 to 27% WPG existing between BHRs and WPG and acetyl group content, respectively, requires only a few samples to calibrate FTIR. Partial least-squares regression models based on second derivatives of the NIR spectra in the wavenumber range from 6080 to 5760 cm-1 resulted in a R2 value of 0.99, number of PLS components (rank) between 3 and 5, root-mean-square error of cross-validation between 0.6 and 0.79%, and a residual prediction deviation up to 10. Although a wide range of input parameters (i.e., various wood species and different procedures of acetylation) was used, highly satisfactory results were obtained. Both FTIR and NIR spectroscopic means fulfill the need for determining the WPG and the acetyl content of acetylated wood. By reason of its additional potential for on-line process control, the NIR method may even outperform the FTIR method.     

利用粘度法和二维红外相关光谱法研究胶原/羟丙甲基纤维素共混物的相互作用

采用粘度法和二维红外相关光谱法对胶原/羟丙甲基纤维素共混体系的相容性及相互作用进行了研究。粘度法测定结果表明,羟丙甲基纤维素含量<30%时共混体系相容,超过50%则不相容。二维红外相关光谱法的分析结果表明,当羟丙甲基纤维素含量<30%时,归属于羟丙甲基纤维素的C—O(H)伸缩振动峰1061cm-1与归属于胶原酰胺带的CO对称伸缩振动峰1660cm-1、N—H摇摆振动峰1553cm-1和N—H面内变形振动峰1238cm-1之间存在同步负交叉峰,表明胶原和羟丙甲基纤维素之间存在氢键作用;而当羟丙甲基纤维素含量>30%时,同步图中负交叉峰强度减小的同时同步峰1061cm-1的强度明显变大,表明此时羟丙甲基纤维素与胶原之间的氢键作用变弱,羟丙甲基纤维素更倾向于在自身分子之间形成氢键。     

Room temperature plasma oxidation in DCSBD: A new method for preparation of silicon dioxide films at atmospheric pressure

In this paper a new process for the preparation of thin silicon dioxide (SiO₂) film is presented: the oxidation of c-Si (1 1 1) surface in atmospheric pressure plasma at room temperature. Diffuse coplanar surface barrier discharge (DCSBD) at atmospheric pressure in air and oxygen atmosphere has been used. The oxidation rate and the thickness of oxidized layers were estimated by ellipsometry. The structure and the chemical composition of oxidized layers were investigated by infrared reflection absorption spectroscopy (IRRAS), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray (EDX) analysis. Scanning electron microscopy (SEM) was used to observe the morphology of the layer surface. It was found that stoichiometric SiO₂ layers were obtained with oxidation rates comparable to thermal oxidation.     

采用二维红外技术研究交联对碱溶胶原结构的影响

以N-羟基琥珀酰亚胺己二酸酯(NHS-AA)为交联剂,交联改性碱溶胶原,采用二维红外相关光谱法研究了交联对胶原二级结构的影响。研究发现,交联未影响胶原红外特征吸收峰的位置,但1672、1554和1241cm-1归属于胶原酰胺I带的CO伸缩振动、酰胺Ⅱ带的C—N伸缩与N—H弯曲振动和Ⅲ带的N—H面内变形振动峰之间存在同步正交叉峰,表明随交联共价键的增加,胶原的链段构象发生了变化。在NHS-AA用量增加的过程中,胶原二级结构变化的顺序为:酰胺Ⅲ带>酰胺Ⅰ带>酰胺Ⅱ带>—CH3>—CH—。由此可见,二维红外相关分析法能提供由交联引起的胶原构象动态变化的微观信息,为进一步研究改性胶原结构与功能之间的关系提供实验依据。