Molecule energies are quantised
Substance exposed to radiation
\(10^{13}\rightarrow 10^{14}\)Hz
Vibrational energy changes
Specific IR frequencies absorbed
\[c=\lambda f\]
Wavenumber =\(\frac{1}{\lambda}\)cm-1
Simple diatomic molecules one vibrate one way
Stretching
Only one absorption
More complex molecules vibrate in many different ways
Fingerprint region below 1500cm-1
Identification by comparison
Intensity dependent on change in bond polarity
Hydrogen bonding broadens peaks due to \(OH\) stretching vibration