Rice professor’s nanotube theory confirmed

They noted in the paper that the results provide a basis for further research into growing specific types of nanotubes. “Now that we know what the growth rate is for a particular chirality nanotube, one could think about trying to achieve growth of that specific chirality by influencing growth conditions accordingly,” Rao said. “So, basically, we now have another ‘knob’ to turn.”

“This work is at a very early development stage, and it’s all about post-nucleation,” Yakobson said. “Nucleation sets what I think of as the genetic code – very primitive compared to biology – that determines the chirality and the speed of growth of a nanotube.” He said it may be possible someday to dictate the form of a nanotube as it begins to bubble up from a catalyst, “but it will take a lot of ingenuity.”

Yakobson revealed a formula last year that defined the nucleation probability through the edge energies for graphene, which is basically a cut-and-flattened nanotube. But the earlier and related dislocation theory applies to the following growth, and if confirmed further may turn out to be his masterwork.

“The dislocation theory of growth is elegant and simple,” Rao said. “It’s still too early to say that it is the only growth mechanism, but Boris should be given plenty of credit for proposing this bold idea in the first place.”

Co-authors are former Rice graduate student Tonya Leeuw Cherukuri and David Liptak, both researchers at the Air Force lab.

The Air Force Office of Scientific Research and the National Research Council funded the work.

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Read the abstract at http://www.nature.com/nmat/journal/vaop/ncurrent/abs/nmat3231.html

Images for download:

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By learning to grow and measure single nanotubes, scientists at the Air Force Research Laboratory were able to confirm a theory by Rice Professor Boris Yakobson that predicted the chirality of a nanotube – its “DNA code” – controls the speed of its growth. (Credit: Rahul Rao/Air Force Research Laboratory)

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Air Force researchers mounted nanoparticle catalysts on microscopic silicon pillars and heated them with lasers to trigger nanotube growth. They were then able to determine the rate of growth and the tubes’ chiralities. (Credit: Rahul Rao/Air Force Research Laboratory)

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A single nanotube stretches out across a microscopic silicon pillar in the Air Force Research Laboratory experiment. (Credit: Rahul Rao/Air Force Research Laboratory)

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