Laser-Raman spectroscopy applications

Laser Raman Spectroscopy and Its Application to the Study of Adsorbed Species... 

There are, at present, two overriding reasons an experimentalist would choose to employ laser Raman spectroscopy as a means of studying adsorbed molecules on oxide surfaces. Firstly, the weakness of the typical oxide spectrum permits the adsorbate spectrum to be obtained over the complete fundamental vibrational region (200 to 4000 cm-1). Secondly, the technique of laser Raman spectroscopy is an inherently sensitive method for studying the vibrations of symmetrical molecules. In the following sections, we will discuss spectra of pyridine on silica and other surfaces to illustrate an application of the first type and spectra of various symmetrical adsorbate molecules to illustrate the second. 

Though as yet in its infancy, the application of laser Raman spectroscopy to the study of the nature of adsorbed species appears certain to provide unusually detailed information on the structure of oxide surfaces, the adsorptive properties of natural and synthetic zeolites, the nature of adsorbate-adsorbent interaction, and the mechanism of surface reactions. 

S.K. Freeman, Applications of Laser Raman Spectroscopy, Wiley, New York, 1974. 

Gilson, T. R., Hendra, P. J. Laser Raman spectroscopy. London Wiley 1970. Bhagavantam, S., Venkatarayudu, T. Theory of groups and its application to physical problems. Bangalore Bangalore Press 1951 New York Academic Press 1969 Proc. Roy. Soc. 130A, 259 (1931) Proc. Indian Acad. Sci. 9A, 224 (1939). 

Laser Raman Spectroscopy and Its Application to the Study of Adsorbed Species R. P. Cooney, G. Curthoys, and Nguyen The Tam... 

It may be concluded, from the analysis of the Raman results, that the information provided by Raman spectroscopy is, in essence, similar to that of infrared spectroscopy. The exploitation of the data, namely, the frequencies and intensities due to the molecular vibrations, is of a certain benefit in giving some insight as to the conformations of carbohydrates, and their interactions with the environment. As laser-Raman spectroscopy is applicable to solids, as well as to aqueous solutions, the linear relationship between Raman intensities and mass concentrations, and the specificity and high quality of the spectra experimentally obtained, make this technique particularly promising in investigations of the chemistry and biochemistry of carbohydrates. 

The first review of laser Raman spectroscopy of explosives appeared in the late 1960s [30], A patent application for laser Raman applied to the remote identification of hazardous gases from explosives decomposition was filed a few years later [31],... 

Recent technical developments in laser Raman spectroscopy have made it possible to measure the Raman spectra of short-lived transient species, such as electronically excited molecules, radicals and exciplexes, which have lifetimes on the order of nano- (10-9) and pico- (10-12) seconds. These shortlived species may be generated by electron pulse radiolysis, photo-excitation and rapid mixing. However, the application of electron pulse radiolysis is limited in its adaptability and selectivity, while rapid mixing is limited by mixing rates, normally to a resolution on the order of milliseconds. Thus, photoexcitation is most widely used. 

C. A. Melendres, Laser Raman spectroscopy Principles and applications to corrosion studies, in Electrochemical and Optical Techniques for the Study and Monitoring of Metallic Corrosion (M. G. S. Ferreira and C. A. Melendres, eds.), pp. 355-388, and references therein. Kluwer Academic Publishers, The Netherlands, 1991. 

Future studies should emphasize the further application of spectroscopic techniques, AES, LEED, electron energy loss spectroscopy (EELS), and laser Raman spectroscopy to provide a more quantitative understanding of the interaction of sulfur compounds with metal surfaces. 

Freeman RD, Hammaker RM, Meloan CE, Fateley WG (1988) Appl Spectrosc 42 456 Freeman SK (1974) Applications of Laser Raman Spectroscopy, Wiley-Intersc, John Wiley Sons, New York London Sydney Toronto Frei K, Giinlhard HH (1963) J Opt Soc Am 51 83 French MJ, Long DA (1975) J Raman Spectrosc 3 391 Freund SM, Maier II WB, Holland RF, Beattie WH (1978) Anal Chem 50 1260 Friedel G (1922) Ann Phys (Paris) 18 273 Friedl B, Thomson C, Cardona M (1990) Phys Rev Lett 65 915 Friedrich HB, Jung-Pin Yu (1987) Appl Spectrosc 41 227... 

The simultaneous application of EPR/ultraviolet-visible diffuse reflectance spectroscopy (UV-vis-DRS)/online gas chromatography (GC) to characterize working catalysts was realized a few years ago 14), and laser-Raman spectroscopy has recently been coupled with these to provide the first such simultaneous application of three techniques 15). 

This paper reports the application of laser Raman spectroscopy to the characterisations of a series of ZSM-5 materials containing occluded organic cations. 

There is a tendency in discussing a new technique to point out its advantages and that is the approach taken here for laser Raman spectroscopy. It is worth emphasizing that fluorescence still presents a major sampling problem for most commercial materials in the Raman and that at this time infrared is much more widely applicable to applied polymer science. Infrared is generally the more effective tool for trace analyses and for quantitative data. 

Painter, P. C. Coleman, M. M. Koenig, J. L. The Theory of Vibrational Spectroscopy and Its Application to Polymeric Materials Wiley New York, 1982. Gilson, T. R. Hendra, P. J. Laser Raman Spectroscopy Wiley New York, 1970. Koningstein, J. A. Introduction to the Theory of the Raman Effect Reidel Dordrecht, 1972. 

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