Knowledge Bank

cis,cis octatetraene undergoes photoisomerization to cis,trans octatetraene at low temperatures in an n-octane matrix. We have shown that this takes place in the $11Bu$ state and determined the energy barrier for isomerization in this excited state from measurements of the low temperature fluorescence and the temperature dependence of the fluorescence decay rates. The barrier for excited state isomerization will be compared to the much larger barrier that have been implicated for the isomerization on the ground state surface.