Single Electron Tunneling in Small Molecules

Abstract

Abstract. We discuss current-and noise-spectroscopy of small molecules weakly coupled to electrodes using master equations. The Coulomb interaction and size quantization effect on the molecule restrict the transport to the tunneling of single electrons. We consider situations where orbital-, spin-or vibrational excitations localized on the molecule play a role or even dominate the transport. For each case, we analyze mechanisms which lead to negative differential conductance (NDC) and even total suppression of the current. The shot noise is shown to provide additional information due to its sensitivity to asymmetries in state-and electrode-specific tunnel couplings. Combined current-noise spectroscopy could be very useful for characterization of experiments.

External field control of charge transmission through single molecules: Switching effects and transient currents

“…The approach is well suited to study the case of direct charge transmission through the molecule. If charge transmission proceeds in a sequential way including intermediate state relaxation subsequent current formation is best described by master equations governing molecular state populations [12][13][14][15][16][17][18][19][20][21][22][23][24]. In particular, all the studies underlined the need to account for non-equilibrium vibrational distributions in the molecule.…”

Charge transmission through single molecules: Effects of nonequilibrium molecular vibrations and photoinduced transitions

“…This is the case if the transferred electrons spent a time-interval in the molecule comparable to the characteristic time of vibrational relaxation. Now, the use of master equations governing molecular state populations is appropriate for the computation of IV-characteristics (see [9,[18][19][20][21][22][23][24][25][26][27][28][29]). …”