The Air Force Research Laboratory in Dayton, Ohio, has experimentally confirmed a theory by Rice University Professor Boris Yakobson that foretold a pair of interesting properties about nanotube growth: That the chirality of a nanotube controls the speed of its growth, and that armchair nanotubes should grow the fastest.
The work is a sure step toward defining all the mysteries inherent in what Yakobson calls the "DNA code of nanotubes," the parameters that determine their chirality -- or angle of growth -- and thus their electrical, optical and mechanical properties. Developing the ability to grow batches of nanotubes with specific characteristics is a critical goal of nanoscale research.
The new paper by Air Force senior researcher Benji Maruyama; former Air Force colleague Rahul Rao, now at the Honda Research Institute in Ohio; Yakobson and their co-authors appeared this week in the online version of the journal Nature Materials.
It's an interesting denouement in a saga that began with a 2009 paper by Yakobson and his collaborators. That paper, which presented the theoretical physicist's dislocation theory of chirality-controlled growth, described how nanotubes emerge as if single threads of atoms weave themselves into the now-familiar chicken-wire-like tubes. It also garnered a bit of controversy over what precisely the results meant.
"Boris caught some heat over it," Maruyama said. "The experimental work out there indicated his theory might be true, but they couldn't confirm it. The good part about our work is that it's fairly unambiguous."
Yakobson, Rice's Karl F. Hasselmann Professor of Mechanical Engineering and Materials Science and professor of chemistry, took it all in stride. "The criticism didn't affect anything; it was actually the best advertisement and motivation for further work," he said. "In fact, (nanotube pioneer Sumio) Iijima noted early that 'helicity may aid the growth.' We have trans
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