Fluorescence quantum yield and lifetime of `redʹ polydiacetylene chains isolated in their crystalline monomer matrix

The fluorescence yield, η≈0.30, and lifetime, τ≈52 ps, of recently discovered `redʹ polydiacetylene isolated chains [R. Lécuiller, J. Berréhar, C. Lapersonne-Meyer, M. Schott, Phys. Rev. Lett. 80 (1998) 4068] have been measured at 15 K. These values show that the relaxation scheme of the `red-chainʹ exciton is very different from that of the usual `blue chainsʹ, and that excited states of Ag symmetry are not present in the optical gap of red chains. Moreover, the radiative lifetime is very short at τrad≈170 ps.