Аннотация:The infra-red spectra of acetaldehyde and acetaldehyde-d4 have been measured between 3μ and 25μ. An analysis of the spectra has been made and values are suggested for the fundamental vibration frequencies of these molecules. These values are compared with the assignment for the propylene molecule, and a strong similarity is shown. The results have been used to calculate the height of the potential barrier restricting internal rotation in acetaldehyde, and a value of about 2000 cal. is deduced.
