Atomic scale dynamic scanning force microscopy images and force versus distance measurements at low temperatures on a cleaved KBr (0 0 1) single crystal are reported. Two distinct forms of atomically resolved contrast were observed. In one case, a nanotip was formed through a tip change. In this case, a strong corrugation of 0.07 nm was measured. It was possible to reverse this tip change intentionally. In the second case, the observed contrast was only 0.025 nm. The force-distance measurements are well modelled with a van der Waals force in the distance range of 0.5-15 nm. The residual forces at smaller tip-sample distances show a maximum attraction of 0.3 nN and decay within 0.2 nm. (C) 2002 Elsevier Science B.V. All rights reserved.