The observability of poorly bound powder-like material on hard surface by atomic force microscopy

Various working modes of atomic force microscopy (AFM) are compared as imaging surfaces with poorly bound, easy-to-displace powder-like material on it. The poorly bound amorphous/turbostratical carbon structures are formed by laser ablation on the top of highly oriented pyrolytic graphite (HOPG) surface. Working in contact mode, these structures can easily be displaced by the AFM tip. Non-contact (low amplitude resonance) mode experiments proved to be adaptable to image the debris-like material, while tapping amplitude and phase detection mode measurements do not yield proper topographic information of it. On the other hand, tapping modes have the advantages of following the topography of a hard surface even when covered with poorly bound materials. Model calculations describing tip motion and the feedback circuit of the piezo driver confirm the observed phenomena.