TIME RESOLVED AND FREQUENCY SELECTIVE FLUORESCENCE OF THE CHL a DIMER

$^{*}Department of Chemistry, Carleton University,Ottawa K1S 586, Canad 1) A. de Wilton and J.A. Koningstein, J. Phys. Chem. to be published (Jan. 1983)Author Institution: Department of Chemistry, Carleton University OttawaThe pulsed laser induced fluorescence of solutions of Chlorophyll a is reported. The $assignment^{1}$) of the fluorescence in terms of contribution of that of monomers, dimers and higher aggregates is discussed. The assignment is based on time resolved fluorescence spectral results in combination with the wavelength selective excitation of fluorescence of primarily the dimeric species. Quenching of this fluorescence, observed at high laser power, is observed and a discussion of this effect is given in terms of our present knowledge of the energy level scheme of the dimer on relation to that of the monomer. Energy gaps of the lowest lying exciton states of dimeric Chl a in $CCl_{4}$, hexane and benzene is reported