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

TL;DR

This study investigates the photoluminescence properties of nitrogen-doped C60 fullerite across 20-230 K, revealing a temperature-dependent transition in adsorption mechanisms and a novel low-temperature quenching effect linked to chemical interactions.

Contribution

It presents the first observation of temperature-dependent photoluminescence intensity and a new low-temperature quenching phenomenon in nitrogen-doped C60 fullerite.

Findings

Identification of a temperature boundary at 420°C for adsorption transition

First recording of temperature dependence of nitrogen-containing substance luminescence

Discovery of low-temperature quenching due to exciton trapping and nonradiative processes

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.