Scanning tunneling potentiometry   I developed a new technique for measuring the electrochemical potential of a surface using a scanning tunneling microscope, and demonstrated a sensitivity approaching the Johnson noise limit. "Scanning tunneling measurements of potential steps at grain boundaries in the presence of current flow", J.R. Kirtley, S. Washburn, and M.J. Brady, IBM Journal of Research and Development, May 1988. "Direct measurement of potential steps at grain boundaries in the presence of current flow", J.R. Kirtley, S. Washburn, and M.J. Brady, Phys. Rev. Lett. 60,1546(1988).