Test tube chemistry inside a carbon nanotube
Thursday 5 February 2009
At the University of Surrey, test tube chemistry just took a leap down in size to the nano-scale, with new test-tubes measuring only about one billionth of a metre across. The scaling factor is like scaling up from a normal test tube to one a hundred kilometres across. When chemistry is performed in a conventional manner in laboratory test tubes, the reactions that occur are a result of billions and billions of molecules reacting with each other and with anything else we put into the tube. Being able to watch or control chemical reactions between individual molecules at this scale is like understanding and then controlling the interaction between two people on a tube train while you are sitting in the International Space Station!
An international team of researchers led by Dr. Hidetsugu Shiozawa of the Advanced Technology Institute at Surrey have been able to see individual events at atomic scale, as molecules react inside the confines of a nano-test tube. In the study the researchers show how a cerium organometallic compound reacts with individual atoms in the walls of the nano-test-tube made from a one-atom-thick sheet of carbon atom ‘chicken-wire’, called a carbon nanotube. They followed the reaction by measuring changes in the electrical properties of the tube when the molecule reacts with it.
Dr. Shiozawa says: “The excitement of this nano-test-tube chemistry experiment is the strong electronic interaction observed at the elemental level when compounds are confined within carbon nanotubes. The quantized electronic states of the tube allow specific molecules and compounds to interact, so we can tell the difference between molecules. We see a change in the properties of the tube from insulating to conducting when electrons hop from the molecule to the tube. This is a fundamental breakthrough, seen experimentally using the Synchrotron facilities in Berlin.”
Professor Ravi Silva, Director of the Advanced Technology Institute, stated: “Our results are world leading and will tell researchers and technologists working on the next generation of nanoelectronic devices some of the fundamental issues that must be taken into account in their design. We have shown that single atoms stuck on the surface of a carbon nanotube can have a tremendous effect on its electrical characteristics. The implications are widespread because these tubes are proposed to be used as wires in nano-scale integrated circuit chips within the next decade.”
The research is published in Physical Review Letters, and the research was sponsored by a Portfolio Partnership award by the Engineering and Physical Sciences Research Council (EPSRC), UK.
H. Shiozawa, T. Pichler, C. Kramberger, M. Rümmeli, D. Batchelor, Z. Liu, K. Suenaga, H. Kataura, and S. R. P. Silva. Screening the missing electron: Nano chemistry in action, Physical Review Letters 102, 046804 (2009)
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