Scanning Tunneling Microscopy Observation of Graphite Surfaces Irradiated with Size-Selected Ar Cluster Ion Beams

Abstract

A cluster ion irradiation system with cluster size selection has been developed to study the effects of the cluster size in surface processing using cluster ions. A permanent magnet with a magnetic field of 1.2 T was installed for size separation of large cluster ions. Traces formed on a graphite surface by the impact with Ar cluster ions under an acceleration energy of 30 keV were investigated by scanning tunneling microscopy. The nature of the traces is strongly affected by the number of constituent atoms of the irradiating cluster ion. When the cluster ion is composed of 100–3000 atoms, crater like traces are observed on the irradiated surfaces. In contrast, such traces are not observed at all with the irradiation of the cluster ions composed of over 5000 atoms. This behavior is discussed on the basis of the kinetic energy per constituent atom of the cluster ion.

Preferential Sputtering of DNA Molecules on a Graphite Surface by Ar Cluster Ion Beam

“…The doughnut-shaped traces in this image proved to be craterlike defects induced on the graphite surface by collision with a single Ar cluster ion. 7,27 The detailed features of the defects, such as cross-sectional height profile, are described elsewhere. 27 Briefly, the bright area indicates a region that is higher than the graphite surface level, and the darker part surrounded by the brighter region indicates a region that is lower than the surface level of the nonirradiated graphite surface.…”

“…7,27 The detailed features of the defects, such as cross-sectional height profile, are described elsewhere. 27 Briefly, the bright area indicates a region that is higher than the graphite surface level, and the darker part surrounded by the brighter region indicates a region that is lower than the surface level of the nonirradiated graphite surface. The carbon atoms and their lattice structure can be observed outside the craterlike defect as shown in Figure 2b.…”

“…27 This result suggests that bond breaking and desorption processes can be controlled without sputtering of the substrate surface by adjusting the energy per constituent atom of the cluster ion. In this study, the formation of craterlike defects by Ar-GCIB has been investigated.…”

Nano-processing with gas cluster ion beams

“…At the impact energy of 1 keV, no damage was formed in the target. The threshold energy is influenced by cluster size [25]. Cluster ion beams with various size distributions were radiated on Si substrates and the number of displacements was measured using Rutherford backscattering spectrometry (RBS) [26].…”

Graphite dislocations induced by collision of neutral mercury droplets

“…Results of high energy ion cluster collisions with graphite, silicon, and other surfaces have been widely studied both experimentally and theoretically [6][7][8][9][10][11][12]. Some of the common results are nano-craters and surface protrusions, known by several names such as hillocks, bumps.…”