The centrifugal distortion constants for 0-CH₂ -CH₂ -C = 0 were calculated using Dowling and Watson’s formalisms. From the fitting analysis and the deviation of predicted transitions it is concluded that the second formalism must be adopted. For the different parameters we have:
A'=12406.012 ±0.005 MHz; B'=5244.456 ± 0.002 MHz; C'=3869.191 ± 0.002 MHz; dj= -2.08± 0 .05 kHz; djk= -23.6 3± 0.95 kHz; dk= - 33.43 ± 1.69 kHz; dWJ= (0.56± 0.01)X l0-6; dwK = (5.08 ± 0.22)X 10 -6.