FT-Raman spectrometry

M. Lopez-Sanchez, M.J. Ruedas-Rama, A. Ruiz-Medina, A. Molina-Diaz and M.J. Ayora-Canada, Pharmaceutical powders analysis using FT-Raman spectrometry Simultaneous determination of sulfathiazole and sulfanilamide, Talanta, 74, 1603-1607 (2008). 

On-line FT-Raman Spectrometry Measurement Results for the Continuous Hydrosilylation Process... 

FT Raman spectrometry, which was needed because the Raman spectrumgenerated 1064 nm radiation was at too long a wavelength for silicon-based CCD detectors. 

The end product of the hydrosilylation reaction is mixed with an exact amount of the Si-H-containing educt (6 samples). These samples are analyzed in parallel by H NMR and an FT-Raman spectrometry probe head which is connected to the spectrometer via a fiber optical cable. For the FT-Raman measurement, the same parameters are used which will be used later for the real measurement, e.g., measuring time 60 s and background measming before every measurement. 

Armenta, S., S. Garrigues, and M. de la Guardia. 2004. Sweeteners determination in table top formulations using FT-Raman spectrometry and chemometric analysis. Anal. Chim. Acta 521 149-155. 

In Chapters 2 to 8 we describe the theory and instrumentation needed for an appreciation of the way that Fourier transform infrared and Raman spectra are measured today. The sampling techniques for and applications of FT-Raman spectrometry are described in Chapter 18. The remaining chapters cover the techniques and applications of absorption, reflection, emission, and photoacoustic spectrometry in the mid- and near-infrared spectral regions. 

No single technique will compensate completely for the effects of fluctuation noise. The best way to minimize this effect is to use a scan speed that causes the infrared wavelengths to be modulated at frequencies outside the frequency range of the perturbations. Atmospheric scintillation is rarely observed at frequencies much above 500 Hz, so these effects are rarely seen in the mid-infrared spectrum when the mirror velocity is greater than about 1 cm s On the other hand, fluctuation noise can be a major problem when the scan speed is very low, as it is with FT-Raman spectrometry (see Chapter 18) and step-scanning interferometers (see Section 5.5). The possible causes of fluctuation noise in step-scan FT-IR spectrometry have been discussed in some detail by Manning and Griffiths [6]. 

Figure 18.2. FT-Raman spectrum of pentaerythritol tetranitrate shown by Hirschfeld and Chase in the first report of FT-Raman spectrometry [2]. (Reproduced from [2], by permission of the Society for Applied Spectroscopy copyright 1986.)...

Any interferometer that is capable of at least 2-cm resolution at the excitation wavelength (1064 nm) can be used for FT-Raman measurements. Thus just about every interferometer that is sold today could be used for this pmpose. Because the throughput should be optimized, however, it is better to use an interferometer with a 4- or 5-cm-diameter beamsplitter than a smaller size. Since NIR Raman measurements with a Nd YAG laser are made between about 9300 and 6000 cm , the optimal beamsplitter should be one with a quartz substrate. While Cap2 and extended-range KBr beamsplitters have been used for FT-Raman spectrometry, it is usually advisable to purchase a beamsplitter that has been optimized for these measurements, as the higher the beamsplitter efficiency, the higher will be the signal-to-noise ratio of the spectrum. 

APPLICATIONS OF FT-RAMAN SPECTROMETRY 18.4.1. Standard Raman Spectroscopy... 

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