Raman spectroscopy sample preparation

Sample preparation is straightforward for a scattering process such as Raman spectroscopy. Sample containers can be of glass or quartz, which are weak Raman scatterers, and aqueous solutions pose no problems. Raman microprobes have a spatial resolution of - 1 //m, much better than the diffraction limit imposed on ir microscopes (213). Eiber-optic probes can be used in process monitoring (214). 

Minimal sample preparation is involved in Raman spectroscopy samples as thin as a monolayer can be examined. 

See also Environmental and Agricultural Applications of Atomic Spectroscopy Environmental Applications of Electronic Spectroscopy Geology and Mineralogy, Applications of Atomic Spectroscopy Inorganic Compounds and Minerals Studied Using X-Ray Diffraction IR and Raman Spectroscopy Studies of Works of Art IR Spectroscopy Sample Preparation Methods MRI of Oil/Water in Rocks X-Ray Fluorescence Spectrometers. 

See also ATR and Reflectance IR Spectroscopy, Applications Biochemical Applications of Raman Spectroscopy Food Science, Applications of Mass Spectrometry Food Science, Appiications of NMR Spectroscopy Fourier Transformation and Sampiing Theory FT-Raman Spectroscopy, Appiications iR Spectrometers, IR Spectroscopy Sample Preparation Methods IR Spectroscopy, Theory IR Spectral Group Frequencies of Organic Compounds Nonlinear Optical Properties Raman Optical Activity, Spectrometers Raman Spectrometers. 

See also Biochemical Applications of Raman Spectroscopy Far-IR Spectroscopy, Applications IR Spectroscopy, Theory IR Spectrometers IR Spectroscopy Sample Preparation Methods Raman Spectrometers Rayleigh Scattering and Raman Spectroscopy, Theory. 

Raman spectroscopy is a very convenient technique for the identification of crystalline or molecular phases, for obtaining structural information on noncrystalline solids, for identifying molecular species in aqueous solutions, and for characterizing solid—liquid interfaces. Backscattering geometries, especially with microfocus instruments, allow films, coatings, and surfaces to be easily measured. Ambient atmospheres can be used and no special sample preparation is needed. 

Recent developments in Raman equipment has led to a considerable increase in sensitivity. This has enabled the monitoring of reactions of organic monolayers on glassy carbon [4.292] and diamond surfaces and analysis of the structure of Lang-muir-Blodgett monolayers without any enhancement effects. Although this unenhanced surface-Raman spectroscopy is expected to be applicable to a variety of technically or scientifically important surfaces and interfaces, it nevertheless requires careful optimization of the apparatus, data treatment, and sample preparation. 

Raman spectroscopy is one of the most powerful techniques for the characterization of nanocarbons. It is also a convenient technique because it involves almost no sample preparation and leaves the material unharmed. There are four characteristic bands for CNTs The band at 200 cm-1 is called radial breathing mode (RBM). It depends on the curvature and can be used to calculate the diameter of SWCNTs [61]. The relatively broad D-band at 1340 cm-1 is assigned to sp2-related defects and disorder in the graphitic structure of the material. The tangential C-C stretching mode is located at -1560 cm 1 (G-band). The second order mode of the D-band can be observed (G -band,... 

Natural products, from plants and foods to rocks and minerals, are complicated systems, but their analysis by Raman spectroscopy is a growing area. Most examples come from quality control laboratories, motivated to replace current time-consuming sample preparation and analysis steps with a less labor-intensive, faster technique but most authors anticipated the eventual application to process control. Often a method will be practiced in a trading house or customs facility to distinguish between items perceived to be of different qualities, and thus prices. 

The Raman spectra of heroin, morphine and codeine (Fig. 7.10) are highly characteristic because of the change in the bands due to the aromatic ring. The FT-IR spectra of these compounds are quite similar. Near-infrared Raman spectroscopy can provide a rapid method for characterising drugs with minimal sample preparation and analysis time. 

In the geosciences Raman spectroscopy has traditionally been a laboratory tool for structural analysis of minerals. Recent developments in instrumentation make possible the use of Raman spectroscopy as a tool for routine identification of minerals in field situations. The following advantages characterize Raman analysis of minerals no sample preparation in situ real time measurement non-destructive and non-intrusive sampling samples may be transparent or opaque spectra are well resolved and with high information content. 

The limit of detection by Raman spectroscopy was 3-5 weight % for the oxime ester and methacrylonitrile for these samples. The shorter time required to reduce background fluorescence in those samples filtered through activated charcoal indicates that more careful sample preparation and purification would lower this limit. 

Raman spectroscopy is a non-destructive technique that is used in cosmochemistry for identification of minerals and to evaluate the bonding and composition of organic molecules. The technique does not require special sample preparation raw rock samples, polished sections, fine-grained powders, and liquids can be analyzed. Raman spectroscopy is the basis for several instruments that are under consideration for upcoming NASA missions. 

Finally, we have not discussed cases where Raman spectroscopy can be used to study catalysts indirectly, as for example, by extracting a sample from a reactor and preparing a KBr disc for IR or Raman investigation. Such techniques may be useful in special circumstances (50) but have limited applicability with regard to the direct examination of surfaces under reaction conditions. 

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