IBM Scientists Image Charge Distribution within a Molecule for First Time

New technique makes it possible to see how charge is distributed in a molecule

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IBM Scientists Image Charge Distribution within a Molecule for First Time

IBM Zurich has achieved another breakthrough at the nanoscale by demonstrating for the first time the ability to "see" the charge distribution within a single molecule.

To measure the charge distribution, the IBM scientists, who published their work in the jorunal Nature Nanotechnology, used an offspring of Atomic Force Microscopy (AFM) called Kelvin probe force microscopy (KPFM). 

Observers say they expect this development to have a significant impact on a range of applications.

"This work demonstrates an important new capability," says Michael Crommie, Professor in the Department of Physics at the University of California, Berkeley. "Understanding this kind of charge distribution is critical for understanding how molecules work in different environments. I expect this technique to have an especially important future impact on the many areas where physics, chemistry, and biology intersect."

“This technique provides another channel of information that will further our understanding of nanoscale physics," explains Fabian Mohn, a member of the research team that made the breakthrough. "It will now be possible to investigate at the single-molecule level how charge is redistributed when individual chemical bonds are formed between atoms and molecules on surfaces. This is essential as we seek to build atomic and molecular scale devices.”

Among the hoped-for results from this work is a new method for understanding charge separation and charge transport in charge-transfer, or CT, complexes. These CT complexes, which exist at the places where two or more molecules meet and at junctures connecting parts of one large molecule, are where a fraction of the electronic charge is transferred between the molecules, or parts. Gaining a better understanding of how these CT complexes work could aid in the design of molecular-sized transistors that are more energy efficient.

IBM Zurich has been on a bit of a run lately with AFM-related breakthroughs, announcing earlier this month a new ultrasharp silicon carbide tip for an atomic force microscope that is thousands of times more wear-resistant at the nanoscale than previous designs.

In addition to these developments, it was IBM Zurich researchers who in 2009 developed a method for measuring the amount of electric charge in an atom without it being on the surface of a conducting material.  And in the same year, researchers there were the first to make an image of a molecule.

In a sense, this most recent work, which was conducted by the same team of researchers—Mohn, Leo Gross, Nikolaj Moll and Gerhard Meyer—is a combination of both of those earlier developments.



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