Atom tracking for reproducible force spectroscopy at room temperature with non-contactatomic force microscopy

Abstract

A method for reproducible site-specific force spectroscopic measurements at roomtemperature by combining frequency modulation atomic force microscopy and the atomtracking technique is proposed. The atom tracking enables us to compensate the change inthe tip–sample relative position induced by the thermal drift as well as to precisely positionthe tip over the same spot of the surface within sub-Ångström stability. Here, we describe ouratom-tracking implementation and the protocol we have followed for the reproducibleroom-temperature acquisition of series of frequency shift versus tip–sample distance(Δf–Z) curves using this technique. With this acquisition protocol, a large number of equivalentΔf–Z curves can be averaged, resulting in a considerable noise reduction, and therefore avoidingits propagation to the corresponding calculated force curve.