Surface electronic states of adsorbed nitrogen molecules on oxidized nickel surface

We present a new technique to investigate the electronic surface structures of metal electrodes and experimental data on oxidized surfaces of nickel electrodes. The experimental system consists of a simple triode structure and an electromagnet to control the momentum of incident electrons. The magnetic field dependence of the transmission electron current to the metal electrodes depends on the electron density at the electrode surface. When the electron density at the surface is high, the incident electrons are scattered by quantized surface states in the surface potential barrier. On the other hand, in the case of low electron density, the incident electrons show resonance characteristics due to the presence of discrete electronic states as a result of the generation of a periodic surface potential. Molecular nitrogen adsorption causes a change in the surface potential, and the bonding states intermediate between covalent bonds and van der Waal's-like bonds are detected.