Quantum rate electrodynamics and resonant junction electronics of heterocyclic molecules

Abstract

Quantum rate theory encompasses the electron-transfer rate constant concept of electrochemical reactions as a particular setting, besides demonstrating that the electrodynamics of these reactions obey relativistic quantum mechanical rules. The theory predicts a frequency ν = E/h for electron- transfer reactions, in which E = e2/Cq is the energy associated with the density-of-states Cq/e2 and Cq is the quantum capacitance of the electrochemical junctions. This work demonstrates that the ν = E/h frequency of the intermolecular charge transfer of push-pull heterocyclic compounds, assembled over conducting electrodes, follows the above-stated quantum rate electrodynamic prin- ciples. Astonishingly, the differences between the molecular junction electronics formed by push-pull molecules and the electrodynamics of electrochemical reactions observed in redox-active modified electrodes are solely owing to an adiabatic setting (strictly following Landauer’s ballistic presump- tion) of the quantum conductance in the push-pull molecular junctions. An appropriate electrolyte field-effect screening environment accounts for the resonant quantum conductance dynamics of the molecule-bridge-electrode structure, in which the intermolecular charge transfer dynamics within the frontier molecular orbital of push-pull heterocyclic molecules follow relativistic quantum mechanics in agreement with the quantum rate theory.