Chemical tip fingerprinting in scanning probe microscopy of an oxidized Cu(110) surface

Abstract

We present a joint experimental/theoretical study of the oxygen-terminated Cu(110) surface. Noncontact atomic force microscopy (NC-AFM) identifies patches of $p(2\ifmmode\times\else\texttimes\fi{}1)$ and $c(6\ifmmode\times\else\texttimes\fi{}2)$ structures. For the latter reconstruction, we observe distinctly different NC-AFM images depending on the chemical tip identity, which were identified as either Cu, O, or Si terminated. Since knowledge of the chemical structure of the tip asperity in NC-AFM is crucial for controlled imaging and manipulation of atoms and/or molecules on surfaces, this surface is proposed to be used for the tip termination ``fingerprinting,'' i.e., identifying the chemical species at its apex. Practical ways of enforcing the chemical structure of the tip asperity both before as well as at any stage of the imaging or manipulation experiment when numerous tip changes may take place, are also discussed.