CO laser photoacoustic spectroscopy of acetic, deuterated acetic and propionic acid molecules

Abstract Absorption spectra of the CO vibration of the monomers and dimers of acetic acid, deuterated acetic acid and propionic acid in the 1600–1950 cm −1 wavelength range were recorded. As methods, both CO laser photoacoustic spectroscopy (PAS) and simultaneous transmission measurements were applied. The combination of these methods enabled determination of the absorption spectra of fatty acids in the temperature range between 278 and 340 K with high sensitivity and accuracy. On the basis of the recorded spectra, dimerization enthalpies ΔH and entropies ΔS and also integrated band absorbances of the CO vibration of monomers and dimers of all three acids were derived.