MOLECULAR DUMBELLS: MEASUREMENT AND MANIPULATION OF A CONDUCTING MOLECULE

Jason Jennette

Recently it has become possible to measure the conductance of single molecules [1].  More recently experimenters have been able to manipulate the current of conducting carbon nano-tubes while recording their I-V characteristics producing a single electron transistor [2]. We will demonstrate a new method for constructing devices that allow the measurement of the conductance of single molecules.  We achieve this by using gold nano-particles of diameter 2nm to 15nm as the electrodes to the molecules.  Utilising molecules with thiol end groups we allow the molecules and nano-particles to self-organise in solution to form dimers consisting of one molecule bonded with two nano-particles.  By using an AFM manipulation technique to build nano-wires to interface with these constructions we are able to construct these devices on a silicon surface.  In our configuration the molecules lie parallel to the surface while held suspended approximately 5nm away from the silicon.  This formation permits us access to the conducting molecule allowing us to image and manipulate the molecule using STM techniques.  We will also discuss methods for modelling and predicting the conductance of pi-conjugated molecules in our system

[1] M. A. Reed, C. Zhou, C. J. Muller, T. P. Burgin and J. M. Tour, Science 278, 252 (1997).
[2] M. Ahlskog, R. Tarkiainen, L. Roschier, and P. Hakonen, Appl. Phys. Lett. 77, 4037 (2000)