Fingerprint Region
The complex lower-frequency part of an infrared spectrum, below about 1500 cm⁻¹, unique to each compound.
Formula / equation
400–1500 cm⁻¹
Unit
cm⁻¹
In depth
This region contains many coupled skeletal vibrations that are too complicated to assign individually but that together form a pattern unique to each substance. Matching it against a spectral library confirms identity conclusively, in the way a fingerprint identifies a person.
Examples in the real world
Distinguishing propan-1-ol from propan-2-ol, whose functional group regions look almost identical.