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RFT-6000 FT-Raman Attachment


The JASCO Model RFT-6000 FT-Raman attachment is designed for quick. non-destructive FT-Raman analysis of virtually any sample when used in conjuction with the JASCO Model FT/IR-6300 FT/IR Spectrometer.

Unlike dispersive Raman spectroscopy where spectra are normally measured using an excitation wavelength in the visible range, FT-Raman spectroscopy is not plagued by fluorescence form the sample itself or sample impurities. FT-Raman spectroscopy eliminates the interference of strong fluorescence background on weak Raman signals and also eliminates the tedious sample preparation sometimes required by dispersive Raman techniques. Elliminating these barriers drastically expands the potential for FT-Raman analysis to a wide variety of appliations.

The Near-infrared excitation of the RFT-6000 offers other advantages. it is less expensive and allows higher powered lasers tp be ised without photo degradation of the sample. Moving the excitation toward the IR compensates for the loss of sensitivity inherent to weak Raman signals. The gold coated optical surfaces of the FT/IR-6300 enhance the sensitivity of the RFT-6000 allowing analysis of a wide variety of sample types and meeting the needs of a grater number of scientists.

FT Raman performance

One of the major benefits of the FT-Raman unit is its applicability for samples that exhibit fluorescence. In conparison with spectra exited by a visible wavelength laser, the FT-Raman unit makes it relatively easy to measure at a much higher S/N ratio. For instance, Fig.1 shows an example of spectra measured with visible excitation and near-infrared excitation of sodium triphosphate. The interferometric approach brings several advantages including high resolution experiments, quick measurement times and built-in outstanding wavenumber accuracy. Fig.2 shows examples of Raman spectral measurement for carbon tetrachloride.
 

Figure 1
Visible and near-infrared excitation of Sodium triphosphate

Figure 2
Raman spectra of carbon tetrachloride

 

Comparison with Infrared Spectra

Sampling is much more convenient in Raman spectroscopy than in Infrared spectroscopy. In Infrared spectroscopy, polymeric materials must be measured in film form, but in Raman spectroscopy, they can be measured as is. In addition, due to selection rules, Raman spectroscopy makes it easy to measure highly symmetrical vibration modes in which the infrared spectrum cannot be observed. Raman spectroscopy allows measurement in the Far-infrared range making it possible to obtain data concerning the lattice vibration of crystals. Another advantage of Raman spectroscopy is that it allows use of inexpensive and easy-to handle glass as a cell material (transparent in the infrared) even when measuring liquids.
The RFT-6000/FT/IR-6300 combination system is capable of both conventional FTIR Absorption and Transmission as well as FT-Raman measurements, depending on the sample form and purpose. Fig. 3 shows the infrared and Raman spectra of the same L-cystine sample. A highly symmetrical vibration mode as -SS-is readily apparent in the Raman scattering.

Figure 3
Infrared and Raman spectra of L-cystine

 

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