The spectroscopy of salicylaldehydes Electronic absorption spectra

Measurements of the electronic absorption spectra of vapor- and solution-phase salicylaldehydes are reported for wavelengths ≥1900 Å. Three intense absorption band systems are readily assigned as A' (ππ ^∗) ← 1 ¹A' transitions by comparison with all-valence-electron computations. Moderate vibrational structure in the 3 ¹A' (ππ ^∗) ← 1 ¹A' transitions of isotopic salicylaldehydes is analyzed and tentative assignments are made for the coupled vibrations.