Electron transport through single molecules and macromolecular chains: Electronic and optical properties – TransMol

The performance of modern electronics increases on a fast pace thanks to the ongoing miniaturization of the components. However, severe problems arise due to quantum mechanical phenomena when conventional structures are made smaller and reach the nanometer scale. Deeper understanding of electrical current on the nanometer scale is therefore an essential step towards novel nanoelectronics. Measuring the transport of charge through nanoscale molecular structures, especially between interacting molecules is also relevant in biology, where hopping and tunnelling processes have been observed between bases of DNA wires. These effects have been used to detect DNA mutations and localized lesions, and may be involved in in vivo DNA repair. While some progresses have been made to understand the conductance properties of point contacts, single atoms and, to a lesser extend, single molecules, several key aspects of charge transport through nanoscopic molecular junctions remain unclear or completely unexplored.
The goal of this project is to address experimentally and theoretically some of these aspects. Therefore, the conductance of a single molecule junctions as a function of the intimate contact interface between molecules and electrodes will be studied, as well as charge transport from one individual molecule to another. Finally the photons emitted when a current flows through those junctions will be detected; it
should reveal decisive information about inelastic components of the current, and fluorescence mechanisms.
This project leans on the use of scanning tunnelling microscope working under ultra-high vacuum at cryogenic temperatures and adapted to the detection of the photon emitted at the junction. The time correlation of the photons will also by measured. This enables the measure of the electron current, and the intensity, the energy spectrum and statistics of the emitted photons with sub-molecular spatial and sub-nanosecond temporal accuracy. To our knowledge, this experimental apparatus will be the first in the world to operate in these conditions.
Our project is at the interface between organic chemistry, condensed matter physics and optics, and therefore requires experimental and theoretical competences in all of these fields. To this end our team is composed of four young researchers, each specialized in one of these domains.