Paths of bacteriochlorophyll c deexcitation in green photosynthetic bacteria and in a model system

Absorption, photoacoustic, and fluorescence spectra of green bacteria cells , their fragments, and artificial oligomers of bacteriochlorophyll c, with all samples embedded in polivinyl alcohol films, were measured. The topogra phy of polymer films without pigment and containing pigment oligomers or of monomers and small aggregates was established using atomic force microscop y. The images of these three types of films were different. The dimensions of oligomers were evaluated. On the basis of thermal deactivation of variou s pigment forms as well as on the grounds of previously measured lifetimes of their fluorescence, conclusions concerning excitation energy transfer be tween various pigment forms in organisms and in a model system were drawn.