Visible Raman spectra

The resolution of the Raman spectrum is detemiined by the monoclnomator. Furthennore, since the light bemg measured is in the visible region, usually around 20 000 cnc the resolution of the monoclnomator must be significantly better than that of its IR counterpart because the resolving power is described by Av/v. That is, for... 

Fig. 3 a UV-Vis DRS spectra of dehydrated TS-1 catalyst reporting the typical 208 nm (48000cm i) LMCT hand, see Fig. 2h also reported are the four excitation laser lines used in this Raman study near-lR (dotted), visible (full), near-UV (dashed) and far-UV (dot-dashed), b Raman spectra of dehydrated TS-1 obtained with four different lasers emitting at 7 = 1064,422,325, and 244 nm (dotted, full, dashed, and dot-dashed lines, respectively). Raman spectra have been vertically shifted for clarity. Although the intensity of each spectrum depends upon different factors, the evolution of the 7(1125)//(960) ratio by changing the laser source is remarkable. The inset reports the Raman spectrum collected with the 244 nm laser in its full scale, in order to appreciate the intensity of the 1125 cm enhanced mode. Adapted from [48] with permission. Copyright (2003) by The Owner Societies 2003... 

However, the high frequency of the laser irradiation in the visible region may lead to photochemical reactions in the laser focus. Besides, fluorescence can often cover the whole Raman spectrum. Such problems can be avoided by using an excitation wavelength in the near-infrared (NIR) region, e.g. with an Nd YAG laser operating at 1064 nm. Deficits arising from the v dependence of the Raman intensity and the lower sensitivity of NIR detectors are compensated by the Fourier-Transform (IT) technique, which is widespread in IR spectroscopy . ... 

The Mo02+ group manifests itself in the infrared and/or Raman spectrum in the form of an intense two-band pattern corresponding to the symmetric and asymmetric Mo—O stretching vibrations. Values for representative complexes are shown in Table 2 which also displays the lowest visible absorption bands for those complexes where these are available. The infrared (or Raman) absorptions are by far the most characteristic feature by which to identify the presence of the MoO + unit. 

The iron coordination environment defined by the crystal structure corresponds remarkably well to that proposed earlier on the basis of spectroscopic studies [125]. The presence of two distinct tyrosine ligands was indicated by its resonance Raman spectrum and a visible spectrum with two tyrosinate-to-... 

In situ Raman spectra of 2000 A PPy-GOD film, which was deposited on a GC electrode, were recorded in the 0.05 M PB (pH 7.4) solution. Figure 5 shows Raman spectra of the as-polymerized film and of those recorded at -1.0 V and +0.4 V. In the spectrum for the as-polymerized PPy-GOD film, there are several bands which may be due to the PPy (27, 30, 31) 922, 988, 1044, 1345, and 1552 cm"1. The 1345 cm"1 band could also be due to the GOD (2). However, there has been no clear evidence for the observation of resonance Raman spectrum of GOD itself (2), and the observed Raman spectrum for the as-polymerized PPy-GOD film may be totally due to the PPy. Virdee and Hester (30) have previously observed similar spectrum changes for a PPy-S04 film by applying the redox potentials. At any rate, the above spectroscopic data confirmed that the PPy-GOD film was formed on the GC electrode. Both UV-visible and Raman spectroscopic data were also consistent with the CV data, which indicated the presence of the redox reaction of the PPy in the PPy-GOD film. 

Another example comparing spectra for a pure medicinal measured with a dispersive system and spectra of tablets measured on an FT system is shown in Fig. 7-30. As mentioned earlier, the Raman spectrum of ibuprofen measured in the visible region exhibits a fluorescence background. This interference is eliminated by going to the near-IR region for the measurements. In the... 

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