Peculiarities of glass forming of the fullerite C60 saturated by the carbon monooxide molecules: photoluminescence studies
P.V. Zinoviev, V.N. Zoryansky, Yu.E. Stetsenko, and V.V. Danchuk
B. Verkin Institute for Low Temperature Physics and Engineering National Academy of Sciences of Ukraine 47 Nauki Ave., Kharkiv, 61103, Ukraine
Received October 20, 2015
Low temperature (20–230 K) studies were carried out by the spectral-luminescent method of the fullerite C60 saturated by carbon monooxide in the phys-sorption mode. Significant changes of the photoluminescent characteristics of the solutions C60–CO with different concentration of the impurity were found even at small times of intercalation. Strong dependence of CO solubility on the saturation temperature was registered by analyzing the contribution to the luminescence of the “deep X-traps”, and filling of octahedral voids by CO molecules occurs with smaller gradient of the impurity distribution in depth of C60 crystals in comparison with N2. Temperature dependences of the radiation integral intensity of the samples with different concentration of the carbon monooxide were studied. It was found for the first time that CO molecules have significant influence on the process of orientation glass formation and on the rotational dynamics of the C60 molecules in contrast to H2 and N2. In the framework of the model of electron excitations transfer in C60 crystals, there was explained the influence of the polar CO molecule on the processes of the C60 molecules reorientations and changes of their rotations type in the concentrated C60–CO solutions, which leads to observed strong temperature shift of the orientation Tc and glass Tg transitions to the region of low temperatures, which is accompanied by “blurring” of their boundaries.
PACS: 61.48.–c Structure of fullerenes and related hollow molecular clusters; PACS: 71.35.Aa Frenkel excitons and self-trapped excitons; PACS: 78.55.–m Photoluminescence, properties and materials.
Key words: fullerite C60, CO intercalation, photolumi-nescence, Frenkel exciton, glass transition.