PHOTOREACTIONS ON LATEX SURFACES - EXCIMER FORMATION OF 1-PYRENEMETHANOL ON POLYSTYRENE LATEX-PARTICLES

Excimer formation from 1-pyrenemethanol (PyM) and several other pyrene derivatives is investigated in aqueous dispersions of polystyrene (PS ) latex, as well as in homogeneous solutions. The efficiency of excime r formation is markedly enhanced on going from the homogeneous aqueous solutions to the particle surface in the presence of the PS latex. Th is is attributed to adsorption of the probes onto the latex surfaces. The peak height ratio between the excimer and monomer fluorescence ban ds (I-E/I-M) of PyM is measured as a function of the surface density o f the probe. The ratio takes a maximum when the surface density is abo ut 0.3 molecules nm(-2). Analysis of various spectral and kinetic data suggest that the probes are inhomogeneously distributed on the latex surface and that a significant portion of the probes self-associate in to ground state dimeric forms. (C) 1997 Elsevier Science S.A.