Femtosecond spectroscopic studies of the one- and two-photon excited-state dynamics of 2,2,17,17-tetramethyloctadeca-5,9,13-trien-3,7,11,15-tetrayne: a trimeric oligodiacetylene.

The excited-state dynamics of an oligomer of polydiacetylene, 2,2,17,17-tetramethyloctadeca-5,9,13-trien-3,7,11,15-tetrayne, dissolved in n-hexane have been studied by femtosecond fluorescence upconversion and polarized transient absorption experiments under one- and two-photon excitation conditions. Spectroscopically monitoring the population relaxation in the excited states in real time results in a distinct time separation of the dynamics. It has been concluded that the observed dynamics can be fully accounted for on the basis of the two lower excited states of the target molecule.