Time-resolved study of photoluminescence polarization in a-C:H films

The decays of intensity and polarization anisotropy of the photoluminescence (PL) of polymer-like amorphous carbon films have been measured at 300 and 80 K using 4.13 and 2.15 eV excitation. For emission energies, Eem, between 1.8 and 3.5 eV, PL polarization anisotropy decreases within 100 ps and reaches a plateau within 1 ns. The anisotropy plateau increases from 0.02 to 0.12 and the intensity decay time decreases from 1 ns to 40 ps as Eem increases. Anisotropy and intensity decays are interpreted within a dipole–dipole energy transfer (Förster) model.