EXAMINATION OF THE GEOMETRY OF LONG-RANGE TIP SAMPLE INTERACTION IN ATOMIC-FORCE MICROSCOPY

A simple method for the in situ determination of the effective large-s cale curvature of the atomic force microscope (AFM) imaging tip is pre sented. In the method, the interaction between a spherical particle of known radius and a planar surface, both coated with an adsorbed surfa ctant bilayer, in aqueous solution is measured. This standard interact ion is then compared with the measurements of the force of interaction between AFM tips and planar surfaces possessing the same adsorbed sur factant bilayers in aqueous solution. The probable effects of both geo metrical simplifications and surface roughness are considered in the d iscussion of the method. The range from 100 to 400 nm is found to cove r most of the effective radii (R(eff)) for the commonly used microfabr icated silicon nitride tips.