WEST LAFAYETTE, Ind. - Researchers have demonstrated a new imaging tool for rapidly screening structures called single-wall carbon nanotubes, possibly hastening their use in creating a new class of computers and electronics that are faster and consume less power than today's.
The semiconducting nanostructures might be used to revolutionize electronics by replacing conventional silicon components and circuits. However, one obstacle in their application is that metallic versions form unavoidably during the manufacturing process, contaminating the semiconducting nanotubes.
Now researchers have discovered that an advanced imaging technology could solve this problem, said Ji-Xin Cheng, an associate professor of biomedical engineering and chemistry at Purdue University.
"The imaging system uses a pulsing laser to deposit energy into the nanotubes, pumping the nanotubes from a ground state to an excited state," he said. "Then, another laser called a probe senses the excited nanotubes and reveals the contrast between metallic and semiconductor tubes."
The technique, called transient absorption, measures the "metallicity" of the tubes. The detection method might be combined with another laser to zap the unwanted metallic nanotubes as they roll off of the manufacturing line, leaving only the semiconducting tubes.
Findings are detailed in a research paper appearing online this week in the journal Physical Review Letters.
Single-wall nanotubes are formed by rolling up a one-atom-thick layer of graphite called graphene, which could eventually rival silicon as a basis for computer chips. Researchers in Cheng's group, working with nanomaterials for biomedical studies, were puzzled when they noticed the metallic nanoparticles and semiconducting nanowires transmitted and absorbed light differently after being exposed to the pulsing laser.
Then researcher Chen Yang, a Purdue assistant professor of physical
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