Abstract
The fluorescence excitation spectrum of acetaldehyde in its transition à 1 A′′-X~ 1 A′ was discussed for torsional states above the barrier. It was found that the K energy-level structure of 14 0+ 15 5 deviated significantly from the expected parabolic shape. The analysis showed that the K structure and the K state at the lowest energy differed appreciably for the two inversion doublets 14 0+ and 14 0- .