TIP-FORCE INDUCED SURFACE CORRUGATION IN LAYERED TRANSITION-METAL TRICHLORIDES MCL(3) (M=RU,MO,RH,IR)

Layered transition metal trichlorides MCl(3) (M=Ru, Mo, Rh, Ir) were studied with atomic force microscopy (AFM) at different applied forces in the 30-270 nN range to examine the tip-force induced surface corrugations. At low forces the AFM images exhibit the patterns corresponding to the centered hexagon arrangement of the surface Cl atoms. With increasing the force, the AFM pattern changes drastically as a result of the tip-force induced surface relaxation. In this relaxation, the central Cl atoms are more depressed than their neighboring Cl atoms, and the latter undergo a pairing in one direction. These observations reflect the local hardness variation in the surface Cl atoms of the top MCl(3) layer that originates from the interlayer mechanical interactions.