Two-photon excitation spectroscopy of a substituted all-trans hexatriene (iso-tachysterol). Spectroscopic assignments of the low-lying 1‘‘1B u*+’’ and 2‘‘1A g*−’’ ππ* states

Abstract
The two‐photon excitation spectrum of the substituted all‐trans hexatriene, iso‐tachysterol, is taken in EPA (77 K). Comparison of this spectrum with the one‐photon absorption and fluorescence spectra indicate that the system origin of the 2’’ 1A*’’g state lies slightly below the 1’’ 1B*+’’u system origin in EPA (77 K). (AIP)