Pyramidal pits created by single highly charged ions inBaF2single crystals

Abstract

In various insulators, the impact of individual slow highly charged ions (eV-keV) creates surface nanostructures, whose size depends on the deposited potential energy. Here we report on the damage created on a cleaved ${\text{BaF}}_{2}$ (111) surface by irradiation with $4.5\ifmmode\times\else\texttimes\fi{}q\text{ }\text{keV}$ highly charged xenon ions from a room-temperature electron-beam ion trap. Up to charge states $q=36$, no surface topographic changes on the ${\text{BaF}}_{2}$ surface are observed by scanning force microscopy. The hidden stored damage, however, can be made visible using the technique of selective chemical etching. Each individual ion impact develops into a pyramidal etch pits, as can be concluded from a comparison of the areal density of observed etch pits with the applied ion fluence (typically ${10}^{8}\text{ }\text{ions}/{\text{cm}}^{2}$). The dimensional analysis of the measured pits reveals the significance of the deposited potential energy in the creation of lattice distortions/defects in ${\text{BaF}}_{2}$.