FRICTION FORCE MICROSCOPY OF HEAVY-ION IRRADIATED MICA

The effects of energetic heavy ions passing through a solid are reflected in the size, shape, and structure of individual latent tracks. Their detailed study thus provides information on the primary processes of energy deposition, which results in bond breaking, lattice disruption, and increased chemical reactivity. Furthermore, ion track cross sections, being objects very limited in size, are well suited for studies of material properties such as friction on a nanometer scale. The present work displays results of scanning force microscopy of mica, irradiated with 11.4 MeV/u Pb28+ and Xe21+ ions at the UNILAC heavy-ion accelerator of the Gesellschaft fur Schwerionenforschung. Their track diameters were determined to be 10.6 and 7.5 nm, respectively. Recording topographical and lateral force data simultaneously allows one to quantify the contribution of friction to topographic images. In this way the kinetic friction coefficient of the sensor (Si3N4) on the sample (mica) was measured. It was found that the value obtained from the latent track area and from the intact mica lattice differ by a factor of 2.