Surface charge mapping of solid surfaces in water by pulsed-force-mode atomic force microscopy * T. Miyatani, S.Okamoto Department of Biomolecular Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226, Japan A. Rosa, O.Marti University of Ulm, Experimental Physics, Albert-Einstein-Allee 11, D-89069 Ulm, Germany M. Fujihira † (E-mail: mfujihir@bio.titech.ac.jp) Department of Biomolecular Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226, Japan Accepted: 01.10.1997 We have studied the lateral distribution of charges on various surfaces in water by measuring the electrical double layer forces between a Si 3 N 4 atomic force microscope (AFM) tip and the surfaces. By increasing the pH of the solution around the isoelectric point (IEP) of Si 3 N 4 of approximately 6, the charge on the Si 3 N 4 AFM tip was changed from positive to negative. The surface charges of the samples were also controlled by the pH of the solution in which the sample oxides were dipped.When the samples were electronically conductive, the surface charge was controlled by the electrode potentials. When the sample surface was heterogeneous in terms of the isoelectric point or point of zero charge (pzc), the surface charge was changed from one place to the other. As a heterogeneous oxide sample, a quartz plate patterned with alumina was used. The lateral charge distributions on such surfaces were mapped by pulsed-force-mode AFM. The lateral resolution of the present method was found to be approximately 20 nm. * Published as: Miyatani, T., Okamoto, S., Rosa, A., Marti, O. and Fujihira, M. Surface charge map- ping of solid surfaces in water by pulsed-force-mode atomic force microscopy. Applied Physics A (Materials Science Processing), 1998, 66, S349-352 † Author to whom correspondence should be addressed 1