Abstract

Photo induced spectral changes of some molecules containing electronic π systems are investigated and the effect of electrocyclic reactions (ring closure etc) on their electronic structure is considered. Two types of molecules are studied

1) Molecules which exhibit two stable states characterized by different π electron configurations¹⁾ such as

2) electron transfer systems containing a "π electron bridge" linking donor and acceptor which can be modified by a photo induced reaction for example

Static electronic π systems are described by a nearest neighbor Huckel Theory, i.e. by a Hamiltonian of the type

where a_i⁺, a_i are the usual Fermion creation and destruction operators, ε the p electron energy and Γ_ij the coupling between nearest neighbor p orbitals. Due to rotation of molecular fragments Γ_ij depends on the orientation of the relevant p orbitals.

© 1994 Optical Society of America