Fullerene-fullerene collisions

Abstract

Summary. -The results of experimental studies of fullerene-fullerene collisions are presented and compared with molecular dynamics simulations and statistical models. The similarities with and differences to nuclear heavy ion collisions are discussed.PACS 36.40 -Atomic and molecular clusters. PACS 01.30.Cc -Conference proceedings. -IntroductionFullerenes are ideal model systems for investigating the dynamics of molecular, or cluster, systems with a large but finite number of degrees of freedom. They are attractive for a number of reasons: the beauty of C 60 makes it an aesthetically pleasing system to work with; the relative simplicity due to the high symmetry and presence of only one atomic element makes it attractive to theoreticians and the experimental accessibility and ease of production and handling means that fullerenes are beloved by experimentalists and are very suitable systems for developing new experimental methods.Fullerenes show a range of properties which are similar to those of atomic metal clusters (or indeed also to phenomena which occur in nuclear systems on very different energy and time scales) such as thermal emission of electrons [1] (beta decay), black-body type radiation [2] (gamma-ray emission) and particle evaporation [3] (alpha decay). The binding energies and ionisation potentials of the fullerenes and certain metal clusters are such that the three different decay or cooling mechanisms can compete on the microsecond timescale of a typical experiment. Recent experiments have been concerned with investigating the competition between these different mechanisms and in determining which are dominant in which excitation regime. This has relevance, e.g., for extracting the dissociation energies for particle evaporation and for determining the underlying physics of the thermal electron emission [4,5].

Molecular fusion of fullerenes

“…0.02Å 2 but with rather large error bars due to the low signals and complexity of the data analysis). Our recent measurements were able to show that the abrupt drop at just below 200 eV seen in the early measurements was due mainly to a change in fragmentation behaviour (from C 2 evaporation to the break-up of the cage into larger chain and ring fragments), leading to increased scattering, [4], as had been suggested to explain the original measurements [7]. The data have been compared to two simple phenomenological models in Fig.…”

“…1. These models have been discussed in detail previously [3,7]. A simple absorbing sphere model (ASM) predicts a linear dependence of the cross section as (1 − E th /E) close to the energetic threshold E th .…”

“…In our laboratory we have been studying fullerene-fullerene collisions in the intermediate collision energy regime (50-5000 eV) where a number of competing reaction channels occur: scattering [2], fusion [3][4][5], evaporation, (multi-)fragmentation [4] and charge transfer [2,6]. The fusion reaction channel is particularly interesting since there are many similarities but also some important differences compared to the dynamics of nuclear collisions [7]. Our early experiments considered only the reaction products within a small scattering angle range about 0 • [7,6].…”

“…The fusion reaction channel is particularly interesting since there are many similarities but also some important differences compared to the dynamics of nuclear collisions [7]. Our early experiments considered only the reaction products within a small scattering angle range about 0 • [7,6]. The more recent work has concentrated on the scattering angle dependence of the fragmentation [4] and charge transfer [2] products and is able to provide considerable insight into the collision dynamics as well as to confirm the earlier interpretations in terms of simple models.…”

Nanopropulsion from High-Energy Particle Beams via Dispersion Forces in Nanotubes

“…40,41 Increasingly, collisions involving nanotubes and other massive neutral particles are being considered. Examples include, among others, fullerene-fullerene [42][43][44][45] and fullerene-surface collisions, 46 other nanoparticlesurface collisions, [47][48][49] damage to nanotubes in "cold spraying" processes, 50 and nanotube array surface deposition via collision. 51 At the same time, the rapid development of synthesis processes has led to considering nanotubes not just as constituents of the accelerated beam but as the enabling technology of advanced high-energy beam applications.…”