RECOVERY OF THE DISTRIBUTION OF INTERCHROMOPHORIC DISTANCES IN A DONOR-ACCEPTOR COUMARIN SUPERMOLECULE BY TIME-RESOLVED ENERGY-TRANSFER MEASUREMENTS

By excitation and probe spectroscopy, we have measured the intramolecular electronic energy transfer in a bichromophoric coumarin. Here, the linkage between the two constituent chromophores consists of a highly flexible chain containing C-C and C-O bonds. The energy transfer proceeds on a time scale of several picoseconds. The experimental results of the kinetic measurements can be well described by a dipole-dipole interaction model which takes into account a Gaussian distribution of intramolecular distances between the two chromophores. Average intramolecular chromophore separations, as well as estimates for the width of the distribution, can be derived from the experiment.