Infrared Spectra of Crystalline Acetic Acid, a Hydrogen-Bonded Polymer

The polarized infrared spectra of crystalline acetic acid and two of its deuterated derivatives, CH 3 COOD and CD 3 COOD, have been recorded from 400 to 4000 cm −1 at cryogenic temperatures. The spectroscopic results have been interpreted on the basis of a factor group analysis based on two structural models: a crystallographic cell composed of four interacting monomer units some of whose vibrational modes are highly perturbed by hydrogen bonding and a unit cell composed of two noninteracting acetic acid chains. The results are discussed in terms of possible interactions between the hydrogen-bonded acetic acid polymeric chains.