Atomic and chemical resolution in scanning force microscopy on ionic surfaces

We present the results of theoretical modelling concerning the possibility to obtain atomic and chemical resolution in contact and non-contact mode Sc anning Force Microscopy (SFM) and discuss a related issue of a working mode l for interpretation of SFM images. As a prototype system we consider the i nteractions of hard oxide tips with softer alkali halide surfaces in UHV. W e briefly review the results of the molecular dynamics (MD) modelling of co ntact SFM and test some of the assumptions of intuitive SFM models. Then we illustrate the shortcomings of contact SFM by considering an image of a po int defect. The mechanism of resolution in non-contact SFM and the effect o f avalanche tip-surface adhesion are discussed next. A model image of an im purity defect in non-contact SFM is presented. Finally, the status of SFM w ith atomic resolution is discussed. (C) 1999 Elsevier Science B.V. All righ ts reserved.