THE LOWEST TRIPLET-STATE OF TETRADECAHEXAENAL

The lowest tripler state, T-0, of all-trans-tetradecahexaenal has been investigated by means of electron-spin-echo spectroscopy in a magneti c field and in zero field. The directions of the principal axes and th e eigenvalues of the fine-structure tensor have been determined. The t ripler state corresponds to a pi pi excitation. In zero field, T-0 is populated predominantly through the upper spin sublevel which is foun d to decay fastest. Comparison of the relative energies and the decay rates of the sublevels of T-0 with those obtained previously for short er polyenals reveals that both the zero-field splitting and the logari thm of the decay rates are inversely proportional to the total number of double bonds.