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1.
高淑琴  里佐威 《分析化学》1997,25(5):501-504
在液芯光纤内产生预共振和共振喇曼效应,可大度提高喇曼光谱强度,用波长远离样品吸收峰的激光激发观察到了α-甲基吡啶的预共振喇曼光谱。用长1.1m,内径200μm的液芯光纤,波长514.5nm,功率0.80W激光激发获得了β-胡萝卜素在CS2中的共振喇曼光谱,其浓度为2×10^-8mol/L,比普通方法的样品的浓度低2-3个数量级。  相似文献   

2.
前言激光喇曼光谱(Laser Raman Spectroscopy)是在喇曼光谱的基础上引入了激光作为光源而发展起来的。喇曼效应早在1928年已被人们所熟悉了,在三十年代,它曾是研究分子结构的主要手段,这主要是由于当时可见光分光技术和照相感光技术发展的结果。后来,随着实验要求的提高,喇曼光谱的实验困难(主要是喇曼效应较弱,一般仅为入射光强的10~8分之一,因此需要较多的试样和较长时间的曝光,同时又有试样中荧光、迷光等的干扰)给喇曼光谱的进一步发展带来了严重的障碍,因此,发展是缓慢的。六十年代,人们将激光引入了喇曼光谱中,在很大程度上解决了从前喇曼光谱的实验困难,给喇曼光谱的发展开拓了广阔的前景。  相似文献   

3.
宏存茂 《大学化学》1986,1(4):44-47
印度科学家C.V.Raman于1928年首次观测到喇曼散射,因而获得1930年的诺贝尔奖。六十年代激光技术的发展为喇曼光谱提供了理想的光源。强度大,单色性好和偏振性强的激光代替了汞灯。将高质量的双单色仪、光电倍增管和微处理机配于喇曼光谱,使喇曼技术得以飞速的发展和广泛的应用。  相似文献   

4.
采用现场共聚焦显微喇曼光谱研究钴电极在碱性溶液中的氧化还原行为和生成物的喇曼光谱特征。研究结果表明:电位正向扫描时,在-0.64V左右Co氧化生成Co(OH)2和CoO,随着电位正移逐步生成Co3O4,在正电位区电极表面层主要是Co3O4,CoOOH和CoO2等;电位负向扫描时,电极由的高价含氧化合物相继还原为Co3O4和Co(OH)2,并最终还原为Co。由不同电位下的生成物的喇曼光谱可以看出;电  相似文献   

5.
本文报导了不同pH值下荧光素钠吸附于银岛膜的表面增强共振喇曼散射(SERRS)光谱。由于在不同pH值的溶液中荧光素钠具有不同的离子构型, 其SERRS光谱也有所不同, 其差异主要表现在谱线强度的变化而不是频率变化。谱线强度随pH值的变化形式可分为两种类型, 这与其相对应的振动模的性质有关。利用“四级能模型”和共振喇曼理论对实验结果进行了分析。  相似文献   

6.
金纳米粒子组装体系粒子密度与SERS强度的关系   总被引:6,自引:0,他引:6  
利用纳米粒子组装技术制备出金基底/巯基苯胺自组装膜偶联层/金纳米粒子的“三明治”结构。实验结果显示,该结构对偶联层分子的喇曼光谱显示出很好的增强效应,增强因子可达10^5;在表面粒子密度(粒子覆盖度)较低时,表面增强喇曼散射(SERS)强度与表面粒子密度近似呈线性关系;随着表面粒子密度的增加,这种线性关系出现负偏差并在表面粒子密度较高区域出现一个平台;在60 ̄110nm范围内大粒径金粒子对喇曼光谱  相似文献   

7.
DNA中糖苷键碱基侧二共价键的喇曼特性分析   总被引:4,自引:0,他引:4  
分析小牛胸腺DNA的纤维和水溶液两种状态样品的激光喇曼光谱发现,嘌呤碱基糖苷键两侧共价键N9C4与N9C8的喇曼特性表现不同,分析与它们相联的N3与N7原子在原子电荷、一级水合层中水桥的形成,以及核苷酸单位内氢键形成等方面的差异,可认为在DNA水溶液中N9C4明显的减色性是因N3原子的特殊性质所造成。  相似文献   

8.
低浓度样品拉曼光谱的实验研究   总被引:4,自引:0,他引:4  
里佐威  高淑琴  孙成林  Zhang Wei  张玮 《分析化学》2000,28(12):1512-1515
在液芯光纤内产生共振拉曼效应,可以提高拉曼光谱强度10^9倍。测定了10^-10-10^-5mol/L浓度样品的拉曼光谱。实验结果表明,β-胡罗卜素在CS2中1520cm^-1拉曼线的强度(散射系数)、频移、线宽随浓度降低而发生变化。  相似文献   

9.
喇曼光谱学的基础是印度物理学家喇曼(C.V.Ramaa)于1928年在液体中发现的喇曼效应。早期喇曼光谱用高压或低压汞灯作光源。自1960年激光器问世以后,由于应用了 He Ne 或 Ar~ 激光器作为激  相似文献   

10.
用沉积银胶的银镜作活性载体,获得了中位-四-(4-N-乙氧羧甲基吡啶)卟啉络铜(Ⅱ)(Cu(Ⅱ)NEAE)、中位-四-(4-N-氰甲基吡啶)卟啉络酮(Ⅱ)(Cu(Ⅱ)NACN)的近红外富里叶变换-表面增强喇曼光谱(NIRFTSERS),对其谱峰位移作了归属,并与它们的可见激光表面增强共振喇曼光谱(SERRS)作了比较。  相似文献   

11.
The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.  相似文献   

12.

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

  相似文献   

13.
非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。  相似文献   

14.
Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.  相似文献   

15.
针对恶臭测试的环境影响问题,提出了解决的实例方案,并对方案的要点及优缺点进行讨论,此方案在实际操作中具有较好的效果。  相似文献   

16.
In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.  相似文献   

17.
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, Mo, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

18.
袁丽秋 《化学教育》2006,27(5):8-10
面对日益枯竭的能源危机,氢能是一种洁净、最有前景的替代能源。目前在各种制氢的方法中光催化分解水制氢的研究最多,光解水过程中催化剂最关键,本文对利用太阳能光解水的途径、提高光催化反应效率以及光催化剂的开发研究进行了综述。  相似文献   

19.
20.
黄酮化合物的合成研究进展   总被引:2,自引:0,他引:2  
黄酮化合物是一类具有多种生物活性的天然产物,其经典的合成方法主要为查耳酮路线和β-丙二酮路线.近年来出现了许多新技术、新方法.本文介绍了2'-羟基查尔酮的氧化关环法、黄烷酮氧化法、改进的Baker-Venkataraman法及其他合成黄酮化合物的方法.  相似文献   

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