快速消除水汽峰的远红外光谱测量方法

空气中的水汽在远红外区(特别是400 cm-1以下)有强吸收,因此水汽峰的存在严重干扰远红外光谱的质量.该文利用湿度补偿原理除去水汽峰的干扰.在光谱采集过程中,观察水汽吸收带的大小和方向,在采集光谱的同时向光谱仪样品室通入干燥空气或潮湿空气来实时调节光谱仪样品室的相对湿度,使水汽的吸收峰随着扫描次数的增加而变小,最后获得无水汽吸收峰干扰的远红外光谱.实验结果表明,湿度补偿法可以彻底消除水汽吸收峰的干扰,并且具有快速和经济的特点.     

背景吸收强度可调控与扣除干扰组分影响的红外光谱测量方法

多组分混合物的红外光谱由于特征谱带的重叠或部分重叠而给谱峰的归属辨认带来极大的困难。本研究通过扫描两个背景样品(纯KBr压片(1)和KBr+C18TCNQ压片(2))实时合成一系列背景单光束谱。每个背景单光束谱既含有背景样品1的贡献也含有背景样品2的贡献。干扰组分C18TCNQ在系列背景谱中的吸收强度随扫描次数变化而改变。当待测混合物和背景样品中干扰组分的吸收强度相等时,就可以完全扣除干扰组分的影响。本测量方法用于硬脂酸与C18TCNQ混合物中扣除硬脂酸(或者C18TCNQ)的干扰,得到令人满意的结果。合成背景样品中干扰组分的含量在测量时成为与扫描次数有关的变量,为扣除干扰组分的影响提供了直接便利的红外光谱测量方法。     

消除水汽吸收峰干扰的红外光谱测量方法

红外光谱测量时,水汽吸收潜带常掩蔽重要的样品光谱信息.克服水汽干扰的方法有真空技术、干燥气体吹扫技术、样品穿梭技术、光谱差减技术和水汽补偿湿度滴定方法等.该文重点评述了新近发展的用于除去水汽噪音的湿度滴定法.不同于以往方法,该方法允许水汽带在光谱采集前期出现,并根据水汽吸收带的大小和正负方向,适时向光谱仪样品室通入干燥...     

镨乙酰丙酮配合物宽波段光声光谱研究

测量了宽波段范围（紫外可见，近红外及中红外）稀土乙酰丙酮（aa)配合物的光声光谱，检测到了大部分Pr^3 的f-f跃迁谱峰，分析了Pr-O 键性质，解释了谱峰分裂以及谱峰位移的原因。与传统的透射谱和吸收谱相比较，光声光谱具有检测快速，分辨率高以及可进行无损分析等优点，特别是对于稀土离子的f-f跃迁的研究，光声光谱具有一定的独特性。     

苯基二氨三嗪-甲醛树脂高温固化过程的红外光谱研究

本文通过不同平均加成度的A阶苯基二是三嗉甲醛树脂的红外光谱分析,对其红外吸收峰的归属进行了讨论。应用高温红外光谱和差谱技术对两种树脂样品的交联行为进行跟踪观察,由的红外吸收变化和反应体系中甲醛的检测推论了树脂的热固化反应。     

傅里叶变换红外光谱诊断地中海贫血症

为建立简单快速的地中海贫血诊断方法,本研究探讨了以傅里叶变换红外光谱结合水平衰减全反射(FTIR-HATR)技术在地中海贫血诊断中的制样方法及光谱的数据处理方法.在制样预处理中,通过对样品进行稀释并干燥成膜消除水分子对光谱吸收干扰,保持ATR光谱中各波长对样品的穿透深度一致.结果表明,当1652 cm-1吸收度小于1.5时(即透射率T小于4%时),各波峰强度与血红蛋白浓度呈良好的线性关系(r>0.995)及实验重复性(RSD<4%).在数据处理上,改进的相对强度方法用于800～1780 cm-1和2480～3600 cm-1区间的分析.通过与常规的傅里叶去卷积谱及差谱方法相比,本方法可消除样品浓度所带来的影响因素,灵敏地揭示群体数据中组分与结构在不同组间的显著差异,如1638 cm-1处重叠的蛋白二级结构峰,1172 cm-1、1440 cm-1表征脂类物质的吸收峰,1064 cm-1表征磷酸化合物峰位及表征SH的2553 cm-1附近的吸收峰在正常组与地中海贫血组间存在显著差异.从而避免了几个峰位的相对强度所反映的信息不足及选择参比峰的困扰,对揭示整体的差异变化规律有着重要的作用.     

傅里叶变换中红外光谱法检测脑胶质瘤

采用傅里叶变换衰减全反射中红外光谱法检测了19例液氮冻存的脑胶质瘤离体组织样品(星形细胞瘤10例, 少枝-星形细胞瘤9例), 对得到的红外光谱进行分析发现, 恶性程度不同的星形细胞瘤组织的红外光谱存在差异, 并且不同类型的脑胶质瘤组织的红外光谱也表现出较为明显的区别, 因此可以根据各个特征吸收峰的峰位、 峰形及谱峰强度等信息来区分脑胶质瘤, 并初步鉴别脑胶质瘤的性质. 研究结果表明, 通过某些特征吸收峰峰位的变化来鉴别星形细胞瘤和少枝-星形细胞瘤与病理诊断结果的符合率约为80%, 说明傅里叶变换衰减全反射中红外光谱法有望发展成为一种对样品无损伤、 快速的脑肿瘤诊断新方法.     

同步辐射红外光谱成像技术对细胞的研究

同步辐射红外显微光谱技术凭借其超高亮度和高空间分辨率的优势,已经在多学科领域中取得了大量的研究成果。特别是在生物医学领域,同步辐射红外显微光谱可以对无染色、无标记的生物样品进行无损检测并可获得生物分子的大量结构信息,因此得到广泛应用。随着同步辐射红外显微光谱技术的发展,生物化学家和光谱学家已经将研究的重点从组织层次的红外光谱成像（组织红外光谱成像）扩展到细胞层次的红外光谱成像（细胞红外光谱成像）,并在近十年的研究中取得了大量的研究成果,但同时也暴露出一些问题,例如（1）细胞或介质中的水在红外光谱酰胺Ⅰ谱带具有很强的吸收;（2）不平整的细胞表面会导致红外光谱中产生Mie散射;（3）细胞红外光谱的复杂性和不确定性会影响数据分析的有效性和准确性。另一方面,生化学家和光谱学家也为解决这些问题采取了许多有用的策略。因此,本综述首先从样品制备、实验设计以及数据分析等方面对最近十年来细胞同步辐射红外光谱成像技术取得的成果进行了总结,随后介绍了目前细胞红外成像技术面临的问题以及解决策略。我们相信,通过多束同步辐射红外光与焦平面阵列（FPA）探测器的结合,同步辐射红外光谱成像技术在对细胞的结构和功能研究中以及其他领域不同材料的研究中都会逐步显示出独特的作用。     

对苯二酚葡糖苷的几种波谱学定量检测方法

对苯二酚葡糖苷,又名熊果苷,对旱生植物在极其干旱的条件下存活起重要作用.它可以抑制酪氨酸酶的活性,在食品中用作防腐剂.空气中放置的熊果苷稀溶液紫外吸收谱和荧光谱的谱学特性很不稳定,难以用于较长时间内的浓度监测;其分子结构的特点又使得用普通的化学方法进行测定有一定的困难.至今,未见到较好的熊果苷定量检测方法的报道.本文用傅里叶变换红外光谱法监测熊果苷浓度,测量精度和稳定性较好;在用紫外吸收和荧光光谱测定熊果苷时引入氮气对样品溶液进行保护,也可在一定时间内保持测量的较高精度.     

鞋底材料的傅立叶变换红外光谱类型分析

利用傅立叶变换红外光谱技术对收集的29种皮鞋类黑色鞋底样品进行了测定分析,其中24种样品来自不同品牌或型号,5种样品来自同一品牌同一厂家同一批次.从红外光谱图中可以看出,依据红外光谱图中特征峰的峰数、峰位、峰形可将29个鞋底样品分为3大类.同一大类的部分鞋底样品有着相似的红外光谱特征,但在相对峰高比和指纹区中一些弱吸收峰上仍然存在明显差异.同一品牌同一厂家同一批次的鞋底样品红外光谱特征基本一致.这表明傅立叶变换红外光谱法是鉴别鞋底材料的有效方法,可以为案件现场遗留的各种鞋底材料残渣及其擦痕提供种属鉴别及比对分析.     

Effect of Water Vapor Absorption on Measurements of Atmospheric Nitrate Radical by LP-DOAS

During the measurement of atmospheric nitrate radical by long-path differential optical absorption spectroscopy, water vapor strong absorption could affect the measurement of nitrate radical and detection limits of system. Under the tropospheric condition, the optical density of water vapor absorption is non-linearly dependent on column density. An effective method was developed to eliminate the effect of water vapor absorption. Reference spectra of water vapor based on the daytime atmospheric absorption spectra, when fitted together with change of cross section with water vapor column densities, gave a more accurate fitting of water vapor absorptions, thus its effect on the measurements of nitrate radical could be restricted to a minimum and detection limits of system reached 3.6 ppt. The modified method was applied during an intensive field campaign in the Pearl River Delta, China. The NO3 concentration in polluted air masses varied from 3.6 ppt to 82.5 ppt with an average level of 23.6±1.8 ppt.     

Density Functional Theory Study of Infrared and Ultraviolet Spectra of Urea L-Malic Acid

During the measurement of atmospheric nitrate radical by long-path differential optical absorption spectroscopy, water vapor strong absorption could affect the measurement of nitrate radical and detection limits of system. Under the tropospheric condition, the optical density of water vapor absorption is non-linearly dependent on column density. An effective method was developed to eliminate the effect of water vapor absorption. Reference spectra of water vapor based on the daytime atmospheric absorption spectra, when fitted together with change of cross section with water vapor column densities, gave a more accurate fitting of water vapor absorptions, thus its effect on the measurements of nitrate radical could be restricted to a minimum and detection limits of system reached 3.6 ppt. The modified method was applied during an intensive field campaign in the Pearl River Delta, China. The NO3 concentration in polluted air masses varied from 3.6 ppt to 82.5 ppt with an average level of 23.6±1.8 ppt.     

VCSEL based detection of water vapor near 940nm

A vertical-cavity surface-emitting laser (VCSEL) was used to study the absorption spectrum of water vapor in the 940nm region. Measurements were performed in ambient air at room temperature and in a hydrogen-oxygen flame over the temperature range of 1500-1800K. Several rotational absorption lines within the 2v1 + v3 vibrational band were measured. The absorption spectra were well resolved, which demonstrates the feasibility of VCSEL-based spectroscopic measurements of water vapor at room and high-temperature in this spectral region. The results were in good agreement with the values obtained from the HITRAN-96 database.     

Dehumidification and humidification of air by surface-soaked liquid membrane module with triethylene glycol

A novel liquid membrane system, a surface-soaked liquid membrane, with triethylene glycol (TEG) on the hydrophilic-treated surface of the hydrophobic microporous membrane was developed and used for the dehumidification and humidification of air. The selectivity of the TEG liquid membrane for water vapor with respect to air was over 2000, which was derived from the selective absorption of the TEG liquid. A flat-type liquid membrane module with a dual membrane surface was designed, of which the TEG liquid membrane thickness was 18 μm and the permeation area was 0.13 m². The liquid membrane humidifier and dehumidifier consisted of the membrane module and a vacuum pump. As a dehumidifier, the membrane system recovered water vapor at 4.1 g/h from 70%RH room air at 298 K. For use as a humidifier, the air flow was effectively humidified by the permeated water vapor through the membrane module. The effects of the air humidity and sweep air flow rate were studied and discussed. Simple model calculations based on the permeability of the water vapor well predicted the experimental results.     

水蒸气对甲烷在金属铁表面还原NO行为的影响

采用程序控温电加热水平陶瓷管反应器,在N2气氛和模拟烟气气氛中、300~1100℃下,研究了水蒸气对甲烷在金属铁表面还原NO行为的影响,并对反应前、后铁样品进行了X光衍射(XRD)、扫描电子显微镜(SEM)及X光电子能谱(XPS)等表征。结果表明,水蒸气对甲烷在金属铁表面还原NO行为的影响较小。在N2气氛中,水蒸气参与了金属铁的氧化;与无水蒸气时相比,水蒸气存在时NO还原效率有所下降。当水蒸气含量从2.5%增加到7%时,由于水蒸气对金属铁的氧化导致其表面形成疏松的微观孔隙,使得NO的还原效率随水蒸气含量的增加而提高。甲烷则参与了铁氧化物的还原,使铁样品表面形成相对致密的Fe3O4和FeO氧化层,不利于NO与金属铁的接触,使得NO的还原效率低于无甲烷时的结果。在模拟烟气条件下,水蒸气使得甲烷在金属铁表面还原NO的效率增加;在1050℃下,反应段过量空气系数SR1=0.7和燃尽段过量空气系数SR2=1.2时,含7%的H2O和无H2O条件下脱硝效率分别为96.7%和90.6%。而在湿烟气中SO2使NO还原效率略有下降。持久性脱硝实验结果表明,当反应温度为1050℃时,在含7%的H2O、0.02%的SO2的模拟烟气中,1.14%的甲烷在金属铁表面持续50h都能保持90%以上的脱硝效率。     

Pattern Recognition Approach to Vapor Phase Infrared Spectra Interpretation for Gas Chromatography

Abstract

The ability to distinguish functional group and the presence of specific elements in vapor phase infrared spectra is demonstrated using pattern recognition techniques. Kth nearest neighbors analysis was found to be superior to hyperplane separations. Weight-sign feature selection was used to elucidate the significant wavelengths which exhibited agreement with established group frequencies. The use of vapor phase infrared spectra for gas chromatographic peak identification is discussed.     

Fourier-transform infrared study of the reversible interaction of water and a crosslinked epoxy matrix

Fourier-transform infrared spectroscopy is utilized to characterize the interaction of a crosslinked epoxy matrix with sorbed water vapor. The perturbations of the epoxy vibrational spectrum are evidence for weak H bonding between water molecules and polar groups in the resin. The epoxy-water interactions are reversible.     

Solvent vapor annealing induced polymorphic transformation of polybutene-1

Solvent annealing is a facile method for changing the aggregated microstructure and physical properties of polymer materials. In this paper, we addressed the effects of solvent vapor annealing, including chloroform and water vapor, on the polymorphic transformation in both hot-pressed film and electrospun nonwoven of isotactic polybutene-1 (PB-1) by means of in situ Fourier transform infrared spectroscopy (FTIR). The pretty rapid transition rate caused by the increased motion of molecular chains under chloroform vapor is associated with a lowest crystallinity. Also, a decreased crystallinity with the crystal transition occurred in electrospun nonwovens resulting from the relaxation of the stretched molecular chains into amorphous state rather than realignment into crystal form I predominating the crystal transition process.     

High-Temperature Oxidation Resistance of PDC Coatings in Synthetic Air and Water Vapor Atmospheres

This work is aimed at the development and investigation of the oxidation behavior of ferritic stainless-steel grade AISI 441 and polymer-derived ceramic (PDC) protective coatings. Double-layer coatings of a PDC bond coat below a PDC top coat with glass and ceramic passive fillers’ oxidative resistance were studied at temperatures up to 1000 °C in a flow-through atmosphere of synthetic air and in air saturated with water vapor. Investigation of the oxide products formed at the surface of the samples in synthetic air and water vapor atmospheres, at different temperatures (900, 950, 1000 °C) and exposure times (24, 96 h) was carried out on both uncoated steel and steel coated with selected coatings by scanning electron microscopy (SEM) and X-Ray diffraction (XRD). The Fe, Cr₂O₃, TiO₂, and spinel (Mn,Cr)₃O₄ phases were identified by XRD on oxidized steel substrates in both atmospheres. In the cases of the coated samples, m- ZrO₂, c- ZrO₂, YAG, and crystalline phases (Ba(AlSiO₄)₂–hexacelsian, celsian) were identified. Scratch tests performed on both coating compositions revealed strong adhesion after pyrolysis as well as after oxidation tests in both atmospheres. After testing in the water vapor atmosphere, Cr ions diffused through the bond coat, but no delamination of the coatings was observed.