Electronic emission spectrum of p-fluorobenzaldehyde vapour

Abstract

The high resolution electronic emission spectrum of p-fluorobenzaldehyde vapour excited in a discharge is reported for the first time. The spectrum consists of both the ã 3A″−X̃ 1A′ phosphorescence and the à 1A″−X̃ 1A′ fluorescence bands. Whereas all the eleven out-of-plane vibrations appear in the fluorescence spectrum, only the φ-CHO torsional vibration and the φ-CHO wagging vibration appear in the phosphorescence. A total of thirty ground state vibrational frequencies out of the thirty-six possible fundamentals have been obtained from the emission bands. Both the fluorescence and the phosphorescence emission spectra of p-fluorobenzaldehyde are very similar to those of benzaldehyde itself. This shows that the electronic transitions are not very sensitive to the substitution of fluorine at the para position of benzaldehyde.