Infrared and Raman spectrometry

The IR and Raman spectroscopic methodologies are considered in the present section simultaneously, because of the fact that these are complementary experimental techniques. That is, the best possible analysis of the lattice vibrations of materials and the vibrations of molecules is by applying both methods concurrently [54-58], 

Generally, for a vibration to be active in the IR spectra, the IR process must produce a change in the molecular dipole associated with the IR transition. On the other hand, to produce Raman activity, the variation has to be in the polarizability of the molecule during the transition. 

These are analytical tools since the character of the interaction is related to the structure and composition of the materials under test. When IR radiation goes across a sample, some photons are absorbed or suffer an inelastic scattering process caused by the active vibrations of the atoms, molecules, and ions, which compose the test material. The frequencies of the absorbed, or scattered, radiation are exclusively related to a particular vibration mode. Consequently, the process reveals attributes of the test material. Subsequently, IR (absorption) and Raman (scattering) are vibration-based spectroscopic methods widely used for characterizing materials, because they allow qualitative structural information to be obtained. 

An IR spectrum is generally reported as band intensities versus wavenumber. The band intensities are expressed as transmittance, T, or as absorbance A, where the transmittance is 

I0 is the intensity of the incident radiation I is the intensity of the transmitted radiation 

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Adama Mickiewicza Poznaniu, Wydz. Mat., Fiz. Chem., Ser. Chem., 1975,18, 29-48. Study by Infrared and Raman Spectrometry of Molecular and Crystalline Structures of Some Nitrogen Heterocycles , A. Lautie, M. H. Limage and A. Novak, in Proceedings of the 18th Colloquium Spectroscopicum Internationale , 1975, vol. 2, pp. 430-434. 

Jones, R. N., and C. Sandorfy The application of infrared and Raman spectrometry to the elucidation of molecular structure, in Technique of organic chemistry, Vol. IX, ed. W. West. New York Interscience Publishers, 1956. 

Jones RN, Sandorfy C (1956) The Application of Infrared and Raman Spectrometry to the Elucidation of Molecular Structure. In Weissberger A (ed) Technique of Organic Chemistry, vol IX Chemical Applications of Spectroscopy, p 247 Jones RW, McClelland JF (1989) Anal Chem 61 650, 1810 Jones WJ, Stoicheff BP (1964) Phys Rev Lett 13 657 Jonuscheit J, Lehner U, Schrotter HW (1994) (unpublished)... 

Section I covers the more conventional equipment available for analytical scientists. I have used a unified means of illustrating the composition of instruments over the five chapters in this section. This system describes each piece of equipment in terms of five modules - source, sample, discriminator, detector and output device. I believe this system allows for easily comparing and contrasting of instruments across the various categories, as opposed to other texts where different instrument types are represented by different schematic styles. Chapter 2 in this section describes the spectroscopic techniques of visible and ultraviolet spectrophotometry, near infrared, mid-infrared and Raman spectrometry, fluorescence and phosphorescence, nuclear magnetic resonance, mass spectrometry and, finally, a section on atomic spectrometric techniques. I have used the aspirin molecule as an example all the way through this section so that the spectral data obtained from each... 

Jones, R. N. and Sandorfy, C. Infrared and Raman Spectrometry Applications, Technique of Organic Chemistry, Vol. 9 (W. West, ed.) Intersdence, New York, 1956, p. 509. 

Infrared and Raman spectrometry has proven to be a particularly powerful tool for the characterization of a phosphazene with optical properties. A series of of three materials constructed using a phosphazene, a phthalocya-nine, and a thiophosphoryl core with identical pendant substitutions have been compared spectroscopically. " The phosphazene variant (61) is shown. Experiments for the three model compounds yielded very similar data, raising the possibility that the bands associated with the core can be determined by difference. A simpler phosphazene dendron (62), was studied using IR and... 

R. N. Jones, C. Sandorfy. The application of Infrared and Raman spectrometry on the elucidation of molecular structure. In Weissberger s Technique of Organic Chemistry, vol. 9, W. West, eds. Interscience, New York, 247-580, 1956. 

Direct identification methods for vibrational spectra of high-performance thin-layer chromatography (HPTLC) spots such as infrared and Raman spectrometries are limited by the required high quantities of substances. However, recent findings of an enhanced Raman scattering for various compounds adsorbed at metal surfaces give new potential for analytical applications of Raman spectroscopy. ... 

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