Fourier Transform Raman Instrumentation

FT-Raman also benefits from advantages inherent to interferometry high collection efficiency, excellent 

Ultraviolet Raman resonance (UVRR) spectroscopy provides for chemical species identification from both the characteristic vibrational structure and electronic spectra. The resonance enhancement also increases the absolute sensitivity of detection, making it easier to detect the structures. The advantages of UVRR spectroscopy are high sensitivity, lack of fluorescence and suitability for use in aqueous solutions. 

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Solubility of elemental sulphur in NR, EPDM, synthetic polyisoprene and deproteinisedNR was determined over a period of 5 days. By varying the amount of sulphur added to the elastomers, heating the mixtures and analysing them on cooling in a Fourier Transform Raman instrument, both the immediate and long-term solubility could be assayed. Some of the non-elastomeric components could influence the rate and level of crystallisation. 11 refs. 

D Cutler. Fourier transform Raman instrumentation. Spectrochim Acta 46A 131-151, 1990,... 

Fig. 5.10. Optical diagram of a Fourier transform Raman instrument.

Hendra P J, Jones C and Warnes G 1991 Fourier Transform Raman Spectroscopy Instrumentation and Chemical Applications (New York Ellis HonA/ood)... 

P. Hendra, C. Jones, and G. Wames, in Fourier Transform Raman Spectroscopy Instrumental and Chemical Applications, Ellis Horwood, New York, 1991. 

Experimental fluorescence- and Fourier-transform-Raman spectroscopy instrumentation... 

Figure 9.6 Elastic and inelastic scattering of incident light by molecules. Rayleigh, elastic scattering Stokes and anti-Stokes, inelastic scattering. (Reproduced from P. Hendra, P.C. Jones, and G. Warnes, Fourier Transform Raman Spectroscopy Instrumentation and Chemical Applications, Ellis Horwood, Chichester, 1991.)...

P Hendra, C Jones, G Warnes. Fourier Transformation Raman Spectroscopy Instrumental and Chemical Applications. New York Ellis Horwood, 1991. 

The Fourier transform Raman (FT-Raniiin) instrument uses a Michelson interferometer, similar to that used in FTIR spectrometers, and a eontinuoits-wave (CW) Nd-YA(i laser as shown in Figure 18-12. fhe use of a 1064-nm (1.064-pm) source virtually eliminates fluorescence and photodecomposition of samples. Hence, dyes and other fluorescing compounds can be investigated with I T-RarniUi instruments. T he Ff-Raman instrument also provides superior Irequency precision relative to conventional instruments, which enable spectral subtractions and high resolution measurements. 

Hendra PJ, Jones C, Warner G (1991), Fourier Transform Raman Spectroscopy, Instrumentation and Chemical Applications, Ellis Norwood, New York (cf. especially p 246) Knops-Gerrits P-P, de Vos DE, Feijen EJP, Jacobs PA (1997) Microporous Mater 8 3 Burch R, Passingham C, Warnes GM, Rawlence DJ (1990) Spectrochim Acta 46A 243... 

Nowadays, many analytical laboratories are equipped with an infrared (IR) and a Raman spectrometer, be it a dispersive device or a Fourier transform (FT) instrument. Raman and IR spectra provide images of molecular vibrations that complement each other and thus both spectroscopic techniques together are also called vibrational spectroscopy. The concerted evaluation of both spectra gives more information about the molecular structure than when they are evaluated separately. 

Hendra, P.J. Jones, C. Wames, G. Fourier Transform Raman Spectroscopy—Instrumentation and Chemical Applications, Ellis Norwood U.K., 1991. 

Hendra, P., Jones, C. and Warnes, G. Fourier Transform Raman Spectroscopy— Instrumentation and Chemical Applicationsy Ellis Horwood, New York, 1991. 

FT-Raman instrument, 488,491, 492. See also Fourier transform, Raman spectrometers... 

As the reader will see, the evolution in Raman instrumentation did not follow a linear path. The instrument evolution demonstrates significant interactions among the roles played by the sample properties, the excitation wavelength, evolution of the detectors, monochromator design driven to match the detectors, implementation of FT-Raman (Fourier transform Raman), and the surprising impact of the Raman microprobe. As each development is described, there will be small diversions included in square brackets, almost like a point-counterpoint musical exposition, that explain the interplay of these developments. The selection of topics to be included was motivated to expose the evolution of commercial instrumentation for applications in materials science and analytical spectroscopy. Traditionally, there have been numerous other Raman topics that have been quite interesting but not included here because of our selected focus. 

V. FOURIER TRANSFORM-RAMAN (FT-RAMAN) INSTRUMENTS A. Background... 

Skoog et al. [2] emphasized the instmmentation advances of the 1980s and early 1990s. Both Fourier-transform Raman (FT-Raman) spectrometers and single-stage spectrographs are discussed. There is some discussion of optical fiber probes, but none of the Raman microprobe. The authors sketch the theory of Raman scattering and present a classical (polarizability derivative) treatment of selection rules and intensity. Resonance enhancement and surface enhancement are treated briefly. In a textbook noted for its emphasis on instrumentation, there is little discussion of current applications. 

Fourier transform-Raman spectroscopy has been less popular—or at least described less frequently in the literature—than dispersive Raman spectroscopy. Generally, students have been introduced to the practice of FT-Raman spectroscopy on conunercial instruments [8,9]. 

The above describes the commonly utilized instrumentation required for dispersive Raman spectroscopic microscopy. In the past, Fourier transform Raman spectroscopy provided an alternative for coloured and fluorescent samples but the use of near-IR lasers at 1.064 pm together with In Ga As detectors reduced the sensitivity. Recent developments in laser rejection Alters and CCD technologies have rendered dispersive techniques the preferred option. 

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