Conclusions The experimental results indicate that there is no rotation around the double bonds in the ionization of 2, bhexadiene isomers. Each ion structure has a unique photodissociation spectrum, and spectral differences are in accord with the molecular orbital calculations. The spectral differences of the 2, 4 isomers are greater in the visible region than those seen for the 1-chloropropene isomers, I0 and there are also differences, ...