Electronic structure of new donor acceptor substituted chromophores

We have carried out ultraviolet photoelectron spectroscopy (UPS) investigat ions at a synchrotron source (BESSY I) and quantum chemical calculations in order to study correlations between chemical constitution and electronic s tructure of a series of conjugated chromophores. Their pi-electron system w as modified by substitution with different donors and accepters at terminal positions, by changing the molecular Length, by introduction of different conjugated moieties into the central pare of the molecules, and by fluorina tion.