Smallest 'Guitar String' to Weigh Atoms (No Who)



Scott Schrade schrade at akrobiz.com
Fri Sep 24 19:49:50 CDT 2004


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http://news.bbc.co.uk/2/hi/science/nature/3677410.stm
 
Scientists hope that "playing" a tiny guitar string, the smallest ever created, 
will help unravel some of the secrets of the molecular world. 

The string, developed at Cornell University, US, is only 10 atoms across, 
a million times smaller than a normal guitar string. 

It is made from a carbon nanotube, formed from a sheet of carbon one 
atom thick and rolled into a cylinder. 

"As a scientist, the possibility that intrigues me the most is to be able to 
use it to, in essence, weigh things," explained Professor Paul McEwen, 
who helped pioneer the string. 

"If you imagine that you had a guitar string and you glued a little weight 
on to it. It would lower the frequency at which the guitar string vibrated, 
because the extra mass slows it down," he told the BBC's Science In 
Action programme. 

"The same thing happens here, but our string only has a few tens of 
thousands of atoms in it. So, just a few extra atoms, maybe even one, 
might shift the tone of the vibration enough for us to detect it." 

The string of the tiny guitar is anchored at both ends, as in a full-scale 
single-stringed instrument. 

"Even the geometry scales down by a factor of a million," Dr McEwen 
said. 

 This, of course, is not a string you can pluck with your fingers. 

"It isn't actually pulled taut initially. It's got a little bit of slack in it. But 
we can use an electric force to pull down on it, in the same way gravity
might pull down on a string or a chain, and pull it taut that way," he said. 
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- SCHRADE in Akron

"Origins" is coming to PBS Sept. 28.
http://www.pbs.org/wgbh/nova/origins/about.html




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