ORNL researchers have discovered a carbon nanotube-based system that functions like an atom-scale switch. Their approach is to perform first-principles calculations on positioning a molecule inside a carbon nanotube to affect the electronic current flowing across it. The result is an electrical gate at the molecular level: In one position, the molecular gate is open, allowing current through; in another position, the gate is closed, blocking the current. In a silicon chip, the gate is a silicon oxide barrier within the structure of the chip. In the ORNL model, the gate is a short molecule ? encapsulated inside the carbon nanotube?that is about one nanometer in size, or three orders of magnitude smaller than a silicon chip.
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