RESONANT-TUNNELING BANDS AND ELECTROCHEMICAL REDUCTION POTENTIALS

The recent observations of resonant tunneling through unoccupied orbit als of molecular species imbedded in metal-insulator-metal tunnel junc tions are discussed in terms of transient reduction of the molecular s pecies. Electrochemical reduction potentials for the solution phase mo lecular systems are compared to the orbital-mediated tunneling spectro scopy (OMTS) data, and a strong correlation is observed. A simple mode l is proposed that accounts for this correlation. This model also expl ains previous observations of spontaneous and permanent reduction of c ertain compounds in the tunnel junction environment. The model should be equally applicable to resonant tunneling and to spontaneous reducti on observed in the scanning tunneling microscope. Based on the view pr esented here, orbital-mediated tunneling spectroscopy is a new method for providing reduction potentials and affinity levels in adlayers and thin solid films.