Photoluminescence in the temperature range 20-230 K of C${}_{60}$ fullerite doped with nitrogen molecules

Abstract

The optical properties of C${}_{60}$ single crystals, intercalated with nitrogen molecules, were investigated by the spectral-luminescence method in the temperature range 20 - 230 K. The saturation was carried out under the pressure of 30 atm. of N${}_2$ at various temperatures ranging from 200 to 550${}^{\circ }$C. For the C${}_{60}+$N${}_2$ system, the presence of a temperature boundary of the adsorption crossover of about 420${}^{\circ }$C was established (transition from the diffusion mechanism of intercalation - physisorption, to chemical interaction - chemisorption). The temperature dependence of the integrated radiation intensity of a new nitrogen-containing substance based on the C${}_{60}$ fullerite has been recorded for the first time. Quenching of photoluminescence at low temperatures was found. The observed new effect of low-temperature quenching of photoluminescence is explained by the appearance in the process of chemical interaction between the N${}_2$ impurity molecules and the C${}_{60}$ matrix of effective exciton trapping centers and nonradiative deactivation of electronic excitation.

7 pages, 2 figures