共查询到20条相似文献,搜索用时 0 毫秒
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Bruce Chase 《Mikrochimica acta》1987,93(1-6):81-91
The basic experimental aspects of Fourier transform Raman Spectroscopy are reviewed with an emphasis on detector technology. The sensitivity is comparable to dispersive Raman Spectroscopy using visible lasers. The ease of spectral subtraction is demonstrated and examples are given showing the elimination of fluorescence. 相似文献
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Resonance Raman Spectroscopy,and Its Application to Inorganic Chemistry. New Analytical Methods (27)
Robin J. H. Clark Trevor J. Dines 《Angewandte Chemie (International ed. in English)》1986,25(2):131-158
Resonance Raman spectra are obtained when the wave number of the exciting radiation is close to, or coincident with, that of an electronic transition of the scattering species. Such spectra are usually characterized by a very large enhancement of the intensities of particular Raman bands, sometimes with the appearance of intense overtone and combination tone progressions. The technique provides detailed information about excited electronic states because it is only the vibrational modes associated with the chromophore that are resonance-Raman active. Additionally, the high sensitivity is such that compounds at concentrations as low as 10?6 mol/L may be detected, enabling resonance Raman spectroscopy to be used as an analytical tool and for the study of chromophores in molecules of biological interest. 相似文献
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Dr. Giulia Giubertoni Gijs Rombouts Dr. Federico Caporaletti Dr. Antoine Deblais Rianne van Diest Prof. Dr. Joost N. H. Reek Prof. Dr. Daniel Bonn Prof. Dr. Sander Woutersen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202213424
Inspired by ideas from NMR, we have developed Infrared Diffusion-Ordered Spectroscopy (IR-DOSY), which simultaneously characterizes molecular structure and size. We rely on the fact that the diffusion coefficient of a molecule is determined by its size through the Stokes–Einstein relation, and achieve sensitivity to the diffusion coefficient by creating a concentration gradient and tracking its equilibration in an IR-frequency resolved manner. Analogous to NMR-DOSY, a two-dimensional IR-DOSY spectrum has IR frequency along one axis and diffusion coefficient (or equivalently, size) along the other, so the chemical structure and the size of a compound are characterized simultaneously. In an IR-DOSY spectrum of a mixture, molecules with different sizes are nicely separated into distinct sets of IR peaks. Extending this idea to higher dimensions, we also perform 3D-IR-DOSY, in which we combine the conformation sensitivity of femtosecond multi-dimensional IR spectroscopy with size sensitivity. 相似文献
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傅里叶变换红外光谱和傅里叶变换拉曼光谱法无损鉴别药材的真伪 总被引:19,自引:0,他引:19
利用傅里叶变换红外(FT-IR)和近红外傅里叶变换拉曼(NIR FT-aman)光谱法对大黄(西宁大黄)与伪品大黄(华北大黄、山大黄、水根大黄)进行了无损快速的鉴别。结果表明:尽管正品大黄与伪品大黄差别较小,有大部分的化学成分有很大的相同之处,但在红外、拉曼谱图中各自的特征峰较突出,根据谱峰的强度和位置可容易地将它们区别开来。红外和拉曼光谱法相互印证,相互补充,具有快速、准确、操作简单、重复性好、不需对样品进行分离提取,可直接鉴别等特点。 相似文献
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R B Somoano 《Angewandte Chemie (International ed. in English)》1978,17(4):238-245
Photoacoustic spectroscopy is a new analytical tool that provides a simple nondestructive technique for obtaining information about the electronic absorption sprctrum of samples such as powders, semisolids, gels, and liquids. It can also be applied to samples which cannot be examined by conventional optical methods. Numerous applications of this technique in the field of inorganic and organic semiconductors, biology, and catalysis have been described. Among the advantages of photoacoustic spectroscopy, the signal is almost insensitive to light scattering by the sample and information can be obtained about nonradiative deactivation processes. Signal saturation, which can modify the intensity of individual absorption bands in special cases, is a drawback of the method. 相似文献
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EPR Spectroscopy as an Alternative Analytical Method for Copper Determination in Alcoholic Beverages
《Analytical letters》2012,45(4):761-770
ABSTRACT An alternative, highly selective method for cooper(II) analysis in alcoholic beverages (brandies) is proposed using EPR spectroscopy. The method is simple, non destructive, fast and can be used for concentrations down to 100 ppb, with 1.1% (x = 1.55, s = 0.0179) RSD (relative standard deviation) and 98.7% accuracy. 相似文献
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Bernhard Blümich Hans Wolfgang Spiess 《Angewandte Chemie (International ed. in English)》1988,27(12):1655-1672
NMR spectroscopy is an effective method not only for examining liquid samples but also for characterizing molecular sturcture, order and dynamics in amorphous and ordered solids. Recent developments in the area of solid-state NMR spectroscopy span from model-dependent studies of conventional one-dimensional spectra to the more definitive two-dimensional (2D) spectra which provide more specific information. For example, with 2D-NMR spectroscopy it is possible to determine the orientational distribution functions of molecular segments in drawn polymers and to distinguish different mechanisms of complex molecular motions. Following an introduction to basic NMR spectroscopy, an overview of the current state-of-the-art of 2D methods in solid-state NMR spectroscopy is presented and demonstrated with selected examples. 相似文献
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傅里叶变换红外光谱法应用于水-乙醇溶液中海南霉素的测定 总被引:1,自引:0,他引:1
随着化学计量学方法处理光谱重叠和光谱采样技术的发展,红外光谱应用于多组份同时定量分析和过程分析的研究日益受到人们的关注[1~5].海南霉素(C47H79O15Na,分子量907.122)是国家一类新药,用于防治鸡球虫病,易溶于有机溶剂,不溶于水. 相似文献
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大气中痕量气体污染物的傅里叶变换红外光谱分析 总被引:2,自引:0,他引:2
本文从两种类型的长光程气体红外吸收方法的角度,介绍了傅里叶变换红外光谱在大气痕量气体污染物分析中的应用,并评述了它的现状和发展前景。 相似文献
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Horst Kessler Matthias Gehrke Christian Griesinger 《Angewandte Chemie (International ed. in English)》1988,27(4):490-536
An exact knowledge of the structure, dynamics, and reactions of molecules provides the key to understand their functions and properties. NMR spectroscopy has developed, through the introduction of two-dimensional methods, into the most important method for the investigation of these questions in solution. A great variety of different techniques is available. However, for their successful application not only the appropriate equipment is required, but also the right choice of experiments and optimum measurement parameters, as well as a careful evaluation of the spectra. This contribution describes the necessary background for modern NMR spectroscopy. With the aid of the so-called product operator formalism it is possible to understand pulsed Fourier transform NMR spectroscopy both qualitatively and quantitatively. Very few, readily understandable assumptions are sufficient for confident application of these methods. This article attempts to introduce in a simple manner this formalism as well as phase cycles necessary for the understanding of pulse sequences, and to train the reader through the discussion of several 2D NMR techniques. An overview of the most important techniques is given in the second part of this article. 相似文献
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Optical spectroscopy of a single impurity molecule provides the first truly local probe of host–guest interactions in doped solids. In conventional optical high-resolution experiments with many molecules only ensemble averages of the microscopic parameters can be obtained. In the single-molecule regime, the exquisite sensitivity of an individual dopant molecule to both the local environment and to external perturbations has been exploited in recent experiments to reveal a wealth of fascinating novel phenomena such as spectral diffusion in crystals and polymers, optical modification of a single impurity molecule (spectral hole-burning), local field measurements at the site of a single impurity molecule, and quantum optics in a solid. 相似文献