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Title: Single impacts of keV fullerene ions on free standing graphene: Emission of ions and electrons from confined volume

We present the first data from individual C{sub 60} impacting one to four layer graphene at 25 and 50 keV. Negative secondary ions and electrons emitted in transmission were recorded separately from each impact. The yields for C{sub n}{sup −} clusters are above 10% for n ≤ 4, they oscillate with electron affinities and decrease exponentially with n. The result can be explained with the aid of MD simulation as a post-collision process where sufficient vibrational energy is accumulated around the rim of the impact hole for sputtering of carbon clusters. The ionization probability can be estimated by comparing experimental yields of C{sub n}{sup −} with those of C{sub n}{sup 0} from MD simulation, where it increases exponentially with n. The ionization probability can be approximated with ejecta from a thermally excited (3700 K) rim damped by cluster fragmentation and electron detachment. The experimental electron probability distributions are Poisson-like. On average, three electrons of thermal energies are emitted per impact. The thermal excitation model invoked for C{sub n}{sup −} emission can also explain the emission of electrons. The interaction of C{sub 60} with graphene is fundamentally different from impacts on 3D targets. A key characteristic is the high degree ofmore » ionization of the ejecta.« less
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4] ;  [2]
  1. Department of Chemistry, Texas A&M University, College Station, Texas 77843-3144 (United States)
  2. Institute of Condensed Matter and Nanosciences–Bio and Soft Matter (IMCN/BSMA), Université Catholique de Louvain, 1 Croix du Sud, B-1348 Louvain-la-Neuve (Belgium)
  3. (Sweden)
  4. Materials Characterization Facility, Texas A&M University, College Station, Texas 77843-3122 (United States)
Publication Date:
OSTI Identifier:
22493151
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 16; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; APPROXIMATIONS; COLLISIONS; COMPARATIVE EVALUATIONS; ELECTRON DETACHMENT; ELECTRONS; EMISSION; EXCITATION; FULLERENES; GRAPHENE; INTERACTIONS; IONS; KEV RANGE; PROBABILITY; RESONANCE IONIZATION MASS SPECTROSCOPY; SIMULATION; SPUTTERING