Now, a smart way to control molecules for new breed of electronics

Monday, February 21, 2011

LONDON - An Arizona State University researcher has demonstrated a smart way of controlling electrical conductance of a single molecule, by exploiting its mechanical properties.

This may prove useful in designing of ultra-tiny electrical gadgets, created to perform myriad useful tasks, from biological and chemical sensing to improving telecommunications and computer memory.

Nongjian ‘NJ’ Tao, of the Biodesign Institute at Arizona State University, lead a research team used to dealing with the challenges entailed in creating electrical devices of this size, where quirky effects of the quantum world often dominate device behavior.

“Some molecules have unusual electromechanical properties, which are unlike silicon-based materials. A molecule can also recognize other molecules via specific interactions,” he said.

In the current research, Tao examined the electromechanical properties of single molecules sandwiched between conducting electrodes. When a voltage is applied, a resulting flow of current can be measured.

Tao’s group was able to vary the conductance by as much as an order of magnitude, simply by changing the orientation of the molecule with respect to the electrode surfaces.

Specifically, the molecule’s tilt angle was altered, with conductance rising as the distance separating the electrodes decreased, and reaching a maximum when the molecule was poised between the electrodes at 90 degrees.

The reason for the dramatic fluctuation in conductance has to do with the so-called pi orbitals of the electrons making up the molecules, and their interaction with electron orbitals in the attached electrodes.

When the tilt angle of a molecule trapped between two electrodes is altered, these pi orbitals can come in contact and blend with electron orbitals contained in the gold electrode-a process known as lateral coupling. This lateral coupling of orbitals has the effect of increasing conductance.

The findings have been published in the journal Nature Nanotechnology. (ANI)

Filed under: Science and Technology

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