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Experiments with multi-walled carbon nanotubes (MWCNTs) and graphite as targets in a source of negative ions with cesium sputtering (SNICS) have shown that MWCNTs with nm radii and μm length can be compared with μm-size graphite grains to understand the irradiation effects that include the formation, sputtering of carbon clusters and the resulting structural changes. The simultaneous adsorption of Cs˚ on the surface and bombardment by energetic Cs + is shown to play its role in the cluster formation and sputtering of carbon atoms and clusters (C x ; x ≥1) and the cesium-substituted carbon clusters (CsC x ) as anions. Sputtered species' qualitative and quantitative outputs are related to their respective structures. Structural changes are shown to occur in MWCNTs and seen in SEM 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.

Three C 60 fragmentation regimes in fullerite bombarded by Cs + are identified as a function of its energy. C 2 is the major species sputtered at all energies. For E(Cs + ) < 1keV C 2 emissions dominate. C 2 and C 1 have highest intensities between 1-3 keV with increasing contributions from C 3 and C 4 . Intensities of all fragments maximize around 2 keV. Above 3 keV, fragments' densities stabilize. The roles of and the contributions from direct recoils and collision cascades are determined. Maximum direct recoil energy delivered to the fullerite's C 60 cage ~210 eV at which only C 2 emissions occur is identified and an explanation provided. The three fragmentation regimes under continued Cs + bombardment eventually lead to complete destruction of the C 60 's cages transforming fullerite into amorphous carbon.

The results from mass spectrometry of clusters sputtered from Cs + irradiated single-walled carbon nano-tubes (SWCNTs) as a function of energy and dose identify the nature of the resulting damage in the form of multiple vacancy generation. For pristine SWCNTs at all Cs + energies, C 2 is the most dominant species, followed by C 3 , C 4 and C 1 . The experiments were performed in three stages: in the first stage, Cs + energy E(Cs + ) was varied. During the second stage, the nanotubes were irradiated continuously at E(Cs + ) = 5 keV for 1,800 s. Afterwards, the entire sequence of irradiation energies was repeated to differentiate between the fragmentation patterns of the pristine and of heavily irradiated SWCNTs. The sputtering and normalized yields identify the quantitative and relative extent of the ion-induced damage by creating double, triple and quadruple vacancies; the single vacancies are least favored. Sputtering from the heavily irradiated SWCNTs occurs not only from the damaged and fragmented nanotubes, but also from the inter-nanotube structures that are grown due to the accumulation of the sputtered clusters. Similar irradiation experiments were performed with the multi-walled carbon nanotubes; the results confirmed the dominant C 2 followed by C 3 , C 4 and C 1 .