Saturday, August 29, 2009

Single molecule, one million times smaller than a grain of sand, pictured for first time

Textbook model: A computer-generated image of how we're used to seeing a molecule represented with balls and sticks

Textbook model: A computer-generated image of how we're used to seeing a molecule represented with balls and sticks

'If you think about how a doctor uses an X-ray to image bones and organs inside the human body, we are using the atomic force microscope to image the atomic structures that are the backbones of individual molecules,' said IBM researcher Gerhard Meyer.

3d

A 3D view showing how a single carbon monoxide molecule was used to create the image using a 'tuning fork' effect

The team from IBM Research Zurich said the results could have a huge impact of the field of nanotechnology, which seeks to understand and control some of the smallest objects known to mankind.

The AFM uses a sharp metal tip that acts like a tuning fork to measure the tiny forces between the tip and the molecule. This requires great precision as the tip moves within a nanometer of the sample.

'Above the skeleton of the molecular backbone (of the pentacene) you get a different detuning than above the surface the molecule is lying on,' Mr Gross said.

This detuning is then measured and converted into an image.

To stop the tip from absorbing the pentacene molecule, the researchers replaced the metal with a single molecule of carbon monoxide. This was found to be more stable and created weaker electrostatic attractions with the pentacene, creating a higher resolution image.

Enlarge IBM researchers

IBM researchers Nikolaj Moll, Reto Schlittler, Gerhard Meyer, Fabian Mohn and Leo Gross (l-r) stand behind an atomic force microscope Photo taken by Michael Lowry Image courtesy of IBM Research - Zurich

The experiment was also performed inside a high vacuum at the extremely cold temperature of -268C to avoid stray gas molecules or atomic vibrations from affecting the measurements.

'Eventually we want to investigate using molecules for molecular electronics,' Mr Gross said.

'We want to use molecules as wires or logic switches or elements.'

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