The quasi-line fluorescence excitation spectrum of 1,2-bis (2,3,7,8,12,13,17,18-octaethyl-21H,23 H-porphino) ethane at 4.8 K consists of two subbands with the splitting mean value of 51cm⁻¹, that are ascribed to the donor and the acceptor half of the homodimer. The donor's fluorescence is quenched by an efficient energy transfer to the acceptor. The energy transfer rate of 10¹¹ ...