The Photoisomerization of cis-Stilbene Does Not Follow the Minimum Energy Path

Thermal activation is not required for barrier crossing reactions in the photoisomerization of cis-stilbene, as demonstrated by computer simulations. The activation is achieved by using the excess energy from the photoexcitation. Moreover, the reaction proceeds with large energy transfers but small conformational changes. The reaction pathway is influenced by these effects and also by the solvent.