FRICTION FORCE MICROSCOPY OF HEAVY-ION IRRADIATED MICA

The effects of energetic heavy ions passing through a solid are reflec ted in the size, shape, and structure of individual latent tracks. The ir detailed study thus provides information on the primary processes o f energy deposition, which results in bond breaking, lattice disruptio n, and increased chemical reactivity. Furthermore, ion track cross sec tions, being objects very limited in size, are well suited for studies of material properties such as friction on a nanometer scale. The pre sent work displays results of scanning force microscopy of mica, irrad iated with 11.4 MeV/u Pb28+ and Xe21+ ions at the UNILAC heavy-ion acc elerator of the Gesellschaft fur Schwerionenforschung. Their track dia meters were determined to be 10.6 and 7.5 nm, respectively. Recording topographical and lateral force data simultaneously allows one to quan tify the contribution of friction to topographic images. In this way t he kinetic friction coefficient of the sensor (Si3N4) on the sample (m ica) was measured. It was found that the value obtained from the laten t track area and from the intact mica lattice differ by a factor of 2.