Fingerprint region of the

A further aid to identification comes from the fact that a molecule commonly has complex series of absorptions spanning a range of wavelengths. This fingerprint region of the spectrum may be too difficult to analyze in detail, but its presence enables us to recognize the substance by comparing the spectrum to an atlas of spectra. 

Figure 3. Fingerprint region of the COSY spectrum of RpII in H O showing the amide to a proton connectivities. Cross peaks are labeled with the identity of the amino acid in the sequence from which they arise.

The C—O stretching band is strong and appears in the fingerprint region of the spectrum. The position is somewhat dependent on the physical state of the sample but it is usually possible to ascertain the type of hydroxyl compound under investigation thus m-cresol shows absorption in the phenolic C—O stretching region at 1330 cm " whereas the band at 1060 cm 1 in the spectrum of heptan-l-ol is characteristic for primary alcohols. 

The fingerprint region of the R spectrum is unique to nearly all compounds, but it is very difficult to read iL You should know about the fingerprint region, but you should use IR to identify functional groups based upon the region from t600 to 3500 cm... 

Changes in the fingerprint region of the spectra can also be related to surfactant penetration. The frequency and shape of the 8, CH2 band are very sensitive to intrachain interactions The CH2 wagging defect modes and the C-0 bands of the surfactant appear in this region as well. 

The fingerprint region of the time - resolved spectra (Figure 27) also indicate the huge increase in C ECL at the C2g - water interface due to phase separation. Complete displacement of C26 by the phase of C12E03 does not occur. Thus, although penetration of this more hydrophobic surfactant can occur, a lack of involvement of water in the process results in poorer performance than can be accomplished at lower temperatures by the more hydrophilic C12E04. 

Figure 8. Fingerprint region of the attenuated total reflectance infrared spectrum of etodolac.

Nowadays, many other infrared vibrations are being studied, using the fingerprint region of the mid-infrared, as well as the far and near infrared regions. We will restrict ourselves in this work to the assignments, presented in table 3.2. 

It is highly unlikely that the IR spectra of two different compounds (except enantiomers) will show the same frequencies for all their various complex vibrations. For this reason, the infrared spectrum provides a fingerprint of a molecule. In fact, the region of the IR spectrum containing most of these complex vibrations (600 to 1400 cm-1) is commonly called the fingerprint region of the spectrum. 

Infrared spectroscopy can be applied to V. the characterization of polymeric materials at various levels of sophistication. As most commonly used, it is a rapid and easy method for the qualitative identification of major components through the use of group frequencies and distinctive patterns in the fingerprint region of the spectrum. Let s look at a couple of examples. 

Figure 12.7. Schematic representations of 2D-NMR spectra of the conotoxin MVIIA, (a) The fingerprint region of the TOCSY spectrum with selected spin systems marked, (b) Fingerprint region of the NOESY spectrum showing two (K2-A6 and L11-Y13) sequential walks, (c) NH-NH region of the NOESY spectrum showing correlations between the NH protons of D14 and G15 C16 and T17 and S22 and G23.

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