Abstract

Fast photoisomerisation reactions have proven to be a powerful probe to investigate various aspects of the influence of the solvent environment on reaction dynamics. Among those, the Si-photoisomerisation of stilbene has become one of the most frequently studied model reactions. Whereas the trans-cis-reaction in solution involves a barrier crossing process and occurs on a 10 to 100 ps timescale at room temperature, the corresponding cis-trans-isomerisation is an order of magnitude faster, and its rate in solvents of different viscosity was measured only recently by femtosecond techniques [1,2]. The extremely short Si-lifetime of about 1 ps at room temperature and ambient pressure is thought to indicate that there is either a very small potential barrier to the twisting motion about the ethylenic double bond or that there is none at all [1,2].

© 1992 The Author(s)