Final answer:
The 'fingerprint' region of an IR spectrum contains unique absorbance patterns specific to individual molecules, which are used for identifying compounds when compared to known spectra.
Step-by-step explanation:
The "fingerprint" region of an IR spectrum can be found in the wavelength range of 400 - 1400 cm¹. This region contains unique patterns of absorbance peaks that are characteristic of individual molecules. This intricate and unique set of peaks facilitates the identification of compounds by comparing the IR spectra of an unknown sample to the spectra of known substances.
Although more challenging to discern, functional groups such as amines and ethers may have subtle signatures in the fingerprint region. Carbon-carbon single bonds show absorption in this region, and their characteristic absorption frequencies can differ based on the nature of the bond (single, double, or triple).
Importance of the Fingerprint Region
The fingerprint region is crucial for identifying compounds when a known reference spectrum is available to compare against the unknown sample. Any variance in the pattern can inform on the structural differences between compounds, making the fingerprint region an important tool in organic and analytical chemistry.