Ultrafast reaction dynamics of polyatomic molecules probed by ionization

In the present work, the ultrafast dynamics of the photoinitiated
electrocyclic ring-opening reactions of 1,3,5-cyclooctatriene and
7-dehydrocholesterol are investigated in a fs pump-probe experiment
using ionization as the probe step. Concerning the
1,3,5-cyclooctatriene photoreaction, there are strong arguments for
the participation of two different reaction channels (involving a
3-center and a 4-center substructure) which lead to three products.
Studying the ring-opening reaction of 7-dehydrocholesterol, which
is a substituted cyclic polyene, answers the crucial question to
what extent an ultrafast reaction can be slowed down by the
influence of a steric factor.