Posted: July 10, 2007 |
Chemists close in on molecular switch |
(Nanowerk News) The electronics industry believes that when it comes to circuits, smaller is better -- and many foresee a future where electrical switches and circuits will be as tiny as single molecules.
|
Turning this dream into reality may be a step closer, thanks to a collaboration between chemists at the University of Illinois at Chicago and Japan's RIKEN research institute. The international team successfully formed a single chemical bond on a single molecule, then broke that bond to restore the original molecule -- without disturbing any bonds to adjacent atoms within the molecule.
|
In essence, they created a molecular-sized electronic switch.
|
"The key thing we were after was reversibility," said Michael Trenary, UIC professor of chemistry and one of the lead researchers.
|
Trenary's lab specializes in understanding the workings of surface chemistry -- notably how molecules interact with metals. RIKEN operates a nanoscience center that offers a vibration-free platform for the tool called a scanning tunneling microscope used to perform this molecular-level task. With the ability to cool to temperatures approaching absolute zero to stabilize molecules, the microscope is equipped with a probe that can then manipulate single molecules.
|
"Others have done work at the single-molecule level, but nobody has been able to get the control we have," said Trenary.
|
Working at RIKEN, Trenary and his Japanese colleagues converted methylisocyanide to methylaminocarbyne on a platinum surface -- a chemical mix that holds particular promise in the field of molecular electronics.
|
Methylisocyanide was introduced as a gas into the microscope's vacuum chamber, and the molecules attached to the super-cooled platinum. Next, hydrogen gas was injected, which breaks up into atoms when it contacts the platinum. The hydrogen atoms bonded to the methylisocyanide to form methylaminocarbyne.
|
The microscope can image single molecules and atoms. Using its tiny probe, the researchers manipulated the tip to just above a single molecule and gave it a small electrical pulse. The hydrogen atom popped off -- reversibility was achieved.
|
"It's a way to alter the metal-molecular contact, which is why it's of interest to those in molecular electronics," Trenary said. "There's been a fair amount of research on using isocyanides for molecular electronics, but without understanding the details of the bonding interaction."
|
"You've got to first understand the surface chemistry in detail," he said. "When you understand that, then you can use these probes to manipulate, fine-tune and control the way you want to.
|