Nano-sensors based on single-molecules (2006)

We propose a methodology for probing nanostructures transmitting just one electron, a process of great importance both in nature and in artificial devices. By using single fluorescent molecules as tiny sensors for measuring single-electron displacements (quantised currents) we will study ionisation of quantum dots, charge transfer in photosynthesis centres, and conducting polymers. The challenge includes positioning sensing molecules at very short but controllable distances from the electron path without compromising their chemical stability and ability to emit light and probing this extremely dim light with optical instruments. We address these problems by working at low temperatures, designing special samples and optimizing optics.