Ionization and fragmentation of C{sub 60} by highly charged, high-energy xenon ions
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
- National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States)
C{sub 60} vapor was bombarded by {sup 136}Xe{sup 35+} and {sup 136}Xe{sup 18+} ions in the energy range 420{endash}625 MeV to study the various ionization and fragmentation processes that occur. Since the center-of-mass energies used in this work exceeded those of previous studies by several orders of magnitude, new excitation and dissociation modes were expected and indeed found. Positive ions were extracted from the interaction region and their times of flight were measured both singly and in coincidence with other ionic fragments. A wide range of stable charge states and cluster sizes from monatomic carbon up to C{sub 60} was observed. Even-numbered carbon fragments dominated the heavier mass range but both even and odd carbon numbers occurred at lower masses. Evidence was found for three qualitatively different ionization and fragmentation channels suggesting different ranges of collision impact parameters: ionization of the parent C{sub 60} molecule, loss of even numbers of carbon atoms, and {open_quote}{open_quote}multifragmentation{close_quote}{close_quote} into many small fragments. This latter mode included the production of singly charged C{sub {ital n}}{sup +} fragments with all values of {ital n} being observed from {ital n}=1 up to at least {ital n}=19. We interpret our results in terms of a theoretical model that indicates that the total interaction cross section contains comparable contributions from (a) excitation of the giant dipole plasmon resonance, and (b) large-energy-transfer processes that lead to multiple fragmentation of the molecule. The distribution of fragment cluster masses for {ital n}{approx_lt}20 is reproduced by a {open_quote}{open_quote}percolation theory{close_quote}{close_quote} description analogous to that used to describe multifragmentation of nuclei by high-energy protons. {copyright} {ital 1996 The American Physical Society.}
- DOE Contract Number:
- W-31-109-ENG-38
- OSTI ID:
- 385696
- Journal Information:
- Physical Review A, Vol. 54, Issue 4; Other Information: PBD: Oct 1996
- Country of Publication:
- United States
- Language:
- English
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