The singlet π* ← <i>n</i> spectrum of jet-cooled acetaldehyde

Abstract

The supersonic jet fluorescence excitation spectrum of the singlet π* ← n transition of CH3CHO has been recorded between 29 700 and 30 800 cm−1. The lower frequency vibrational peaks have been analyzed in terms of two upper electronic state (S1) vibrations; the out-of-plane bend (ν′14) and the CH3 torsion (ν′15). A threefold potential with a barrier height of V′3=653 cm−1 gave an accurate fit of the observed ν′15 levels of the S1 state. The allowed transition to the electronic origin has been observed. The value of T0=29 771 cm−1 is considerably higher than recent estimates .