Relative Intensities of Microwave Absorption Lines

Abstract

A method is described for measuring the relative intensities of microwave absorption lines up to 80 mc. apart to within a few percent, using a Stark‐modulated resonant cavity absorption cell of novel design. Barriers to internal rotation in CH₃CHO and CH₃CH₂F have been obtained by measuring the relative intensities of torsional satellites. The resulting barrier heights are: 1103±60 cal for CH₃CHO, 3310±210 cal. for CH₃CH₂F, in good agreement with the values 1162±30 cal for CH₃CHO, and 3306±100 cal for CH₃CH₂F obtained from splitting measurements by Kilb, Lin, and Wilson, and by Herschbach, respectively. Correction factors are given for errors in intensity and splitting measurements due to small doublet splittings.