Fingerprint bands

Other fingerprint bands characteristic to methimazole are at 1466, 1570 and 1271 Cm 1 as shown in Figure 4. 

Other characteristic fingerprint bands are 1500, 1U50, 1U30, 1360, 1310, 1250 cm"1. 

Table 2 Infrared fingerprint bands associated with the various adsorbates ammonia, pyridine, acetone, and water when separately exposed to 24 Co/UC and 24 Cu/UC (designations w and s refer to weak and strong bands respectively).

OH defonnation vibration can be found in the region 1410 - 1260 cm . Strong C-0 valence vibrations between 1150 and 1040 cm" overlap with aromatic fingerprint bands at 1225 - 950 cm". CH3 symmetric deformation vibrations occur in the region 1370 - 1190 cm". Ofter authors ascribe the 1049 cm-1 region to C-OH and C-C stretching mode (27, 28). However, it is not excluded that the FTIR spectra may contain useful information located in too weak peaks not visible by direct visual inspection. More specific chemical and spectroscopic application knowledge is required to fully interpret this plot. 

The carbonyl stretching and other fingerprint bands of keto H BT show only minor changes of their spectral envelope and the spectrally integrated absorption as a function of time. In particular, contributions from the v = 1 2 transition of... 

Do not try to assign all the bands in the spectrum. Fingerprint bands are unique to a particular system. Occasionally, intense bands will be fingerprint-type absorptions these bands, generally, will be ignored in the interpretation. Fingerprint bands do, however, play an important role when infrared data are employed for identification purposes. 

FIGURE 12.17 Low resolution infrared spectrum of benzene vapor showing characteristic fingerprint bands of an aromatic ring. (From NIST Chemistry WebBook, http //webbook.nist.gov/chemistry)... 

D. Do not try to account for all the bands. Many of them—sometimes most of them—are fingerprint bands. 

G. Note that most of the bands have not been explained. They are fingerprint bands, not group frequencies. 

Polyvinyl chloride is quite a simple polymer. What should we expect to see in the spectrum There should be CH2 bands near 3000 and 1450 cm and C—Cl-related vibrations near 700 cm In addition, fingerprint bands would... 

The band at 1100 cm lies in the fingerprint region and even though it is quite strong it must be assigned to a fingerprint band. It must be taken into account when comparing with reference spectra to confirm the identification. 

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