Abstract
The vibration spectra of ethylene oxide and ethylene oxide d4 have been analysed simultaneously, yielding twenty-six valence-type potential constants. The method of steepest descent was used to obtain a least-squares fit of the thirty observed frequencies to those calculated from the secular equations deduced by the Wilson FG matrix method. The estimated error in the potential constants is given. The value 1379 cm-1, reported by Kohlrausch and Reitz, is assigned to v7 for C2H4O in place of the estimated value 1345 cm-1 of Lord and Nolin. The values obtained for the principal potential constants agree well with those obtained for molecules having similar structures.