▎ 摘　　要

We present results from experiments and molecular dynamics (MD) simulations obtained with C-60 and Au-400 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 C-60 and Au-LMIS sources with acceleration potentials generating 50 keV C-60(2+) and 440-540 keV Au-400(4+). 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 C-60 impacts on single layer graphene, the secondary ion (SI) yields for C-2 and C-4 emitted in transmission are similar to 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 similar to 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 similar to 50% neutrals and similar to 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. Published under license by AIP Publishing.