Effect of molecular nitrogen impurity on the photoluminescence of fullerite C60.

Polycrystalline samples of fullerite C60 with different concentrations of molecular nitrogen impurity are studied by luminescence spectroscopy at temperatures of 20-230 K. The photoluminescence characteristics of the C60-N2 solutions vary significantly. At T = 20 K there is a significant contribution to the luminescence from emission centers ("deep X-traps") determined by the concentration of N2 molecules in octahedral voids of the fcc C60 lattice. The experimentally observed differences in the effect of nitrogen impurities on the structural and luminescence characteristics of C60-N2 solutions show that the filling of the lattice voids into the depth (from the surface) of the samples is substantially inhomogeneous. The temperature dependences of the integrated emission intensity from samples with different nitrogen concentrations are studied. N2 molecules are found to have little effect on the formation of fullerite orientational glass. A tendency for the vitrification temperature of these C60-N2 solutions to fall with increasing impurity concentration is observed experimentally. [ABSTRACT FROM AUTHOR]