Phonon-progressional V–I characteristics of STM processes mediated by redox molecular adsorbates Original Research Article

STM (scanning tunneling microscopy) currents through large redox molecular adsorbates, such as metalloproteins, are enhanced on a redox state (RS) immersed therein. The enhancement is due to electron-hopping mediation at RS, in general accompanied by simultaneous phonon excitation. It is predicted that the currents have phonon-progressional bias dependence, which enables us to know fundamental physical parameters of RS including its location with respect to both energy and height from the substrate, the energies of both inner-sphere (atomic arrangement) and outer-sphere (molecular arrangement) reorganization, and the energy of phonons participating in the former.