Ne++C60 collisions: The dynamics of charge and energy transfer, fragmentation, and endohedral complex formation

Abstract

Interaction of Ne+ with C60 has been studied for collision energies ranging up to 100 eV. The dominant process is charge transfer, with C60+ accounting for 85% to 100% of the total product signal in this energy range. At 25 eV collision energy, C60-2n+ dissociative charge transfer products appear, accounting for ∼13% of the total product signal at high energies. At ∼25 eV, NeC60+, NeC58+, and NeC56+ all appear together, followed by a series of NeC60-2n+ products where n increases with increasing collision energy. These products are believed to be endohedral complexes, Ne@C60-2n+, where neon is physically trapped inside the fullerene cage. The production efficiency of the endocomplexes reaches a maximum of ∼1.2% at 60 eV, and decreases to 0.5% at 100 eV. Modeling the results leads to the following picture of Ne++C60 collision dynamics: Charge transfer occurs in nearly all collisions, and is the only significant process for high impact parameters. At collision energies below ∼25 eV, translational-to-internal energy transfer is inefficient, even for low impact parameter collisions. At higher energies, the inelasticity jumps to near 100%, leading to fragmentation of the nascent products. Both endohedral penetration and efficient energy transfer appear to require bond rupture in the C60.

Ionization and Fragmentation ofC60via Multiphoton-Multiplasmon Excitation

“…We believe that this result might also provide a clue to understand the apparent fragmentation and double ionization threshold energies found in earlier studies on synchroton radiation [8,9], electron-impact [6,11] and ion-impact excitation [10] of fullerenes.…”

“…Several experiments indicate that fragmentation of C 60 , which generally occurs via the loss of one or more C 2 segments, happens only after excitation above a certain threshold energy. Quite surprisingly, this threshold appears to be much higher than the activation energy for "evaporation" of individual C 2 [6,[8][9][10][11]. Most of these findings have been successfully ascribed to the very large number of internal degrees of freedom of the C 60 molecule that leads to a fast diffusion of the excitation energy followed by statistical, i.e., inefficient, redistribution into ionizing or fragmenting modes.…”

Collisions of rare gas ions with C60: Endohedral formation, energy transfer, and scattering dynamics

“…In addition, we can easily prepare projectile ions such as metal atomic ions, small cluster ions, etc., where it would be very difficult to prepare the corresponding neutral species for C 60 ϩ ϩM scattering. We have studied scattering of atomic ions of neon, 22 lithium, sodium, and potassium, 23,24 boron, 25 carbon, 26 nitrogen, 27 oxygen, 28 fluorine, 25 a variety of transition metals 25,29 as well as Mn 2 ϩ , CO ϩ , and C 2 ϩ . 25 We are able to extract energetics for en-dohedral penetration, substitution reactions, and fragmentation reactions.…”

Collision dynamics of He@C60+He@C60 at low energies

“…All these open a door to applications of fullerene. In addition, it was also found that the rare gases such as He and Ne can form endohedral fullerenes in the forms of Ne@C 56 and He@C 60 by thermal excitation or high energy collisions with fullerene cages [8] .…”