HOW TO DESCRIBE AFM CONSTANT FORCE SURFACES IN REPULSIVE MODE

Calculational techniques have been developed for obtaining the AFM con stant force surfaces when scanning of the tip above the surface of the closely packed atoms in repulsive mode. The existence of a scanning r egime was demonstrated for which the constant force surfaces have brea ks in the regions between crystal atoms if the tip has effectively onl y one atom on its apex. The parameters of minimal atomic cluster on th e tip apex were determined which assures the continuous scanning above both the perfect crystal and the crystal with the point defects of va cancy type. The interpretation of the experimental atomic force images in repulsive mode is discussed.