Cs + sputtered clusters from multi-walled carbon nanotubes, graphite and the structural transformations

► Cs + irradiated MWCNTs investigated with sputtered carbon clusters. ► The fragments include from monomers to large clusters. ► Successive spectra identify the fragmentation to conversion into amorphous carbon. Experiments with multi-walled carbon nanotubes (MWCNTs) and graphite as targets in a source of negative ions with cesium sputtering show that MWCNTs with nanometer radii and micrometer length can be compared with micrometer-size graphite grains. The comparative study helps to better understand the irradiation effects, including the formation, sputtering of carbon clusters and the resulting structural changes. The simultaneous adsorption of Cs 0 on the surface and bombardment by energetic Cs + ions is shown to play a role in cluster formation and sputtering of carbon atoms and clusters (C x ; x ⩾ 1) and the cesium-substituted carbon clusters (CsC x ) as anions. Qualitative and quantitative outputs of sputtered species are related to their respective structures. Structural changes are shown to occur in MWCNTs and seen in scanning electron micrographs. The individual identity of the heavily bombarded MWCNTs may have given way to the merged structures while effects on the structure of heavily irradiated graphite grains size needs to be further investigated.