Vibrational overtone spectra references

The KBr spectrum is employed in the internal-reference technique. In this case, a weak absorption band of the adsorbent (e.g., the overtones of the silica or zeolite lattice vibrations, 2100-1600 cm [119]) acts as the internal reference, and the ratio of adsorbate absorption to the reference absorption is proportional to the quantity of molecules adsorbed. The advantage of this is that it does not require to control precisely the sample weights [120]. 

Polytetrafluoroethylene, — (CF2—CF2) —, is also known commercially as Teflon—see Reference Spectrum 23 for the IR and Raman spectra. The CF2 stretching vibration occurs as the most intense IR absorption band, near 1200 cm This band is a multiplet, and consists of three peaks at 1240, 1215, and 1150 cm Other major bands are located at 641, 554, and 515 cm and are assigned to the CF bending modes. The IR absorption band at 2366 cm is the overtone of the CF2 stretching vibration. 

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