Knowledge Bank

The infrared spectrum of gaseous aluminum chloride has been examined from 1200 to $325cm-1$. At temperatures near the boiling point, $180\circ C$, three bands have been observed. These frequencies 625, 484, and $420cm-1$ are attributed to vibrations of the molecule $Al2Cl6$. At $900\circ C$ only one band located at $610cm-1$, was observed. This frequency is attributed to the monomeric species $AlCl3$. The techniques used appear suitable for the study of the infrared spectrum of substances which are volatile at high temperatures.