Formation and reinforcement of clusters composed of C(60 )molecules

We carry out two experiments: (1) the formation of clusters composed of C(60 )molecules via self-assembly and (2) the reinforcement of the clusters. Firstly, clusters such as fibres and helices composed of C(60 )molecules are produced via self-assembly in supercritical carbon dioxide. However, C(60 )molecules are so weakly bonded to each other in the clusters that the clusters are broken by the irradiation of electron beams during scanning electron microscope observation. Secondly, UV photons are irradiated inside a chamber in which air is filled at 1 atm and the above clusters are placed, and it was found that the clusters are reinforced; that is, they are not broken by electron beams any more. C(60 )molecules located at the surface of the clusters are oxidised, i.e. C(60)O(n )molecules, where n = 1, 2, 3 and 4, are produced according to time-of-flight mass spectroscopy. It is supposed that oxidised C(60 )molecules at the surface of the clusters may have an important role for the reinforcement, but the actual mechanism of the reinforcement of the clusters has not yet been clearly understood and therefore is an open question.