Hypervelocity cluster ion impacts on free standing graphene: Experiment, theory, and applications

Abstract

We present results from experiments and molecular dynamics (MD) simulations obtained with C60 and Au400 impacting on free-standing graphene, graphene oxide (GO), and graphene-supported molecular layers. The experiments were run on custom-built ToF reflectron mass spectrometers with C60 and Au-LMIS sources with acceleration potentials generating 50 keV C602+ and 440–540 keV Au4004+. Bombardment-detection was in the same mode as MD simulation, i.e., a sequence of individual projectile impacts with separate collection/identification of the ejecta from each impact in either the forward (transmission) or backward (reflection) direction. For C60 impacts on single layer graphene, the secondary ion (SI) yields for C2 and C4 emitted in transmission are ∼0.1 (10%). Similar yields were observed for analyte-specific ions from submonolayer deposits of phenylalanine. MD simulations show that graphene acts as a trampoline, i.e., they can be ejected without destruction. Another topic investigated dealt with the chemical composition of free-standing GO. The elemental composition was found to be approximately COH2. We have also studied the impact of Au400 clusters on graphene. Again SI yields were high (e.g., 1.25 C−/impact). 90–100 Au atoms evaporate off the exiting projectile which experiences an energy loss of ∼72 keV. The latter is a summation of energy spent on rupturing the graphene, ejecting carbon atoms and clusters and a dipole projectile/hole interaction. The charge distribution of the exiting projectiles is ∼50% neutrals and ∼25% either negatively or positively charged. We infer that free-standing graphene enables detection of attomole to zeptomole deposits of analyte via cluster-SI mass spectrometry.

Facile Fabrication of Subnanopores in Graphene under Ion Irradiation: Molecular Dynamics Simulations

“…Using the bombardment of carbon and gold clusters, nanopores could also be created in monolayer graphene . However, it is difficult to precisely control the energy and radius of the clusters in experiments. , Bai et al simulated graphene under the bombardment of continuous silicon ions in a confined mask area, and the minimum diameter of the formed pores was about 2 nm. Nanopores fabricated in this approach are inevitably larger than angstrom size due to the accumulated effects of a large number of incident ions, , and it is difficult to efficiently introduce plenty of pores.…”

Crosslinking Multilayer Graphene by Gas Cluster Ion Bombardment

“…M. Gołu ński et al [44] proposed C60 and Ar projectiles for the controlled perforation of graphene. Others proposed the use of freestanding graphene as a substrate for chemical analysis by secondary ion mass spectrometry (SIMS) [46,47].…”

Effect of the Impact Angle on the Kinetic Energy and Angular Distributions of β-Carotene Sputtered by 15 keV Ar2000 Projectiles

“…Therefore, knowledge about these quantities is an important parameter for the successful design of an SNMS experiment. There is a significant database of the angular and the kinetic energy spectra for the atomic projectile bombardment of inorganic samples , Much less is known about directionality and energetics of emission for cluster projectiles, particularly for large gas cluster projectiles bombarding organic solids. − …”