ESR, XPS, UV-VIS AND FT-IR INVESTIGATIONS ON THE INTERACTION OF NO AND O-2 WITH HIGHLY DISPERSED C-60 SUPPORTED ON SILICA, TITANIA AND ALKALI CATION-EXCHANGED

The characteristics of the radical sources in highly dispersed C-60 samples supported on silica, titania and alkali cation-exchanged Y-zeolite were investigated in the presence and absence of NO and O-2 by means of ESR, FT-IR and UV-diffuse reflectance spectroscopies, the results of which were compared with those of the bulk C-60 sample. In the presence of O-2, C-60 dispersed onto supports was found to easily generate ESR signals in ambient conditions or under UV-irradiation. The intensity of the ESR signal of the C-60 samples were found to strongly depend on the dispersibility of C-60, the kind of support and the degassing temperature. Based on these results, the nature of these ESR active species in C-60 was discussed in detail for the first time. The addition of NO led to a dramatic decrease in the intensity of the ESR signal, its extent also strongly depending on the kind of support, i.e., silica or Y-zeolite and the exchanged-alkali cations on zeolite, i.e., H+, Na+, Cs+, while such a decrease was not observed for the bulk C-60.