Eur. Phys. J. D 38, 299-306 (2006)
https://doi.org/10.1140/epjd/e2006-00005-7

Fragmentation and ionization of C₇₀ and C₆₀ by slow ions of intermediate charge

¹ Physics Department, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden
² Division of Ion Physics, Ångström Laboratory, Uppsala University, Box 534, 75121 Uppsala, Sweden
³ Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki, 305-0006, Japan
⁴ Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C, Denmark
⁵ CIRIL/GANIL, rue Claude Bloch, B.P. 5133, 14070 Caen Cedex 05, France

Corresponding author: ^a henning@physto.se

Received: 26 August 2005
Revised: 9 November 2005
Published online: 10 January 2006

Abstract

We have measured total and coincident (with outgoing charge-state analyzed projectiles) ionization and fragmentation spectra of C₆₀ and C₇₀ following collisions with Xe⁴⁺ and Kr⁴⁺ at v = 0.06 a.u. Intact positive fullerene ions in charge states up to five (C₆₀⁵⁺ and C₇₀⁵⁺) are produced with both projectiles and for Kr⁴⁺+C₇₀ collisions we even observe a small C₇₀⁶⁺ peak. The C_60/70-2m³⁺ (m=1–7) intensity distributions are predominantly associated with the stabilization of three electrons on the projectile (s=3) and are significantly different for Xe⁴⁺- and Kr⁴⁺-projectiles. On the other hand, we find remarkable similarities in the C₃⁺-C₁₁⁺ multi-fragmentation pattern regardless of projectile species (mass) although they are associated with closer encounters in which the projectile is fully neutralized (s=4). Simple Monte Carlo calculations of nuclear and electronic loss processes show that both these contributions are very similar in glancing Xe⁴⁺+C₆₀ and Kr⁴⁺+C₆₀ collisions, suggesting that frontal (and more violent) collisions are strongly suppressed under the present experimental conditions. Nevertheless it is surprising that the more distant collisions (s=3) are projectile mass dependent, while the closer collisions (s=4) are not. This indicates that this simple approach (although it reproduces more advanced quantum mechanical calculations for slow collisions with singly charged atomic ions rather well) is not valid for a comprehensive description of the energy transfer processes in the present collision systems involving projectiles of higher charge states.