ESTM study of nanostructure and surface energetic properties of individual chromium and nickel

Abstract

Individual chromium and nickel in air and at interfaces to 0.01 N HCl and 0.1 N H2SO4 solutions are studied with the use of electrochemical scanning tunneling microscopy (ESTM) and electrochemical scanning tunneling spectroscopy (ESTS) at the controlled potentials of the specimen and tip. The potential range of chromium specimens was 0.1 to 0.9 V in 0.01 N HCl and 0.3 to 1.1 V in 0.1 N H2SO4; the potential range of nickel was −0.01 to 0.64 V in 0.01 N HCl and 0.184 to 0.834 V (N.H.E.) in 0.1 N H2SO4. At the controlled potential, the surfaces in the studied acid solutions are smoother than in air. The potential of the specimen affects the electrophysical properties, which determine the electron tunneling transfer, more noticeably than the nanorelief of the metals. The obtained changes in the It,dZ spectra dependence on the distance in air on a field of 1 nm2 at a step of 0.04 nm enabled us to estimate the effective barrier of tunneling Kef between neighbor atoms, which is in good agreement with the known dependence of Kef on the work function.