Energy dependences of the fusion cross section for the collisions C + 60 +C 60 , C + 60 +C 70 and C + 70 + C 70 have been measured. Fusion occurs for energies above a sharp energetic barrier V B. The fusion barrier lies in the region between 60 and 80 eV and increases with increasing number of atoms participating in the collision. For energies beyond the barrier the fusion reaction cross section increases with collision energy to a maximum value and then decreases very rapidly. The highly excited fusion compound decays on the experimental timescale, and the resulting fragmentation pattern has been studied as a function of collision energy. For energies up to 200 eV the fragmentation behaviour can be modelled in terms of successive evaporation of C 2 units from the hot fusion product. At higher energies this model breaks down and another fragmentation mechanism has to be invoked. The overall results are in very good agreement with quantum molecular dynamics simulations and the predictions of simple phenomenological fusion models.

A theoretical study on collisions between fullerenes for the systems C + 60 + C 60 , C + 70 + C 60 and C + 70 + C 70 is presented covering a wide range of collision energies (50 < E < 250 eV in the centre-of-mass frame). Quantum molecular dynamics (QMD) simulations enable a detailed insight into the underlying mechanism of the different reaction channels. The fusion barriers for the investigated systems are determined and compared with experimental data taking into account the finite temperature of the colliding fullerenes. Structural as well as energetic aspects of the reaction mechanism are discussed from a microscopic point of view. As a counterpart to the QMD simulations, a simple phenomenological fusion model is described and compared to the experimental fusion cross section as a function of the collision energy.

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New experimental data is reported for the absolute cross sections for the fusion reaction channel in single gas-phase collisions between fullerenes. The experimental data is compared with the results of quantum mechanical and classical molecular dynamics simulations as well as with simple models. Quantum molecular dynamics simulations are in very good quantitative agreement with the experimental data. The overall dynamical behaviour can be well-described qualitatively in the framework of simple models.