New switch could improve electronics

Researchers at the University of Pittsburgh have invented a new type of electronic switch that performs electronic logic functions within a single molecule. The incorporation of such single-molecule elements could enable smaller, faster, and more energy-efficient electronics.

The research findings, supported by a $1 million grant from the W.M. Keck Foundation, were published online in the Nov. 14 issue of Nano Letters.

"This new switch is superior to existing single-molecule concepts," said Hrvoje Petek, principal investigator and professor of physics and chemistry in the Kenneth P. Dietrich School of Arts and Sciences and codirector of the Petersen Institute for NanoScience and Engineering (PINSE) at Pitt. "We are learning how to reduce electronic circuit elements to single molecules for a new generation of enhanced and more sustainable technologies."

The switch was discovered by experimenting with the rotation of a triangular cluster of three metal atoms held together by a nitrogen atom, which is enclosed entirely within a cage made up entirely of carbon atoms. Petek and his team found that the metal clusters encapsulated within a hollow carbon cage could rotate between several structures under the stimulation of electrons. This rotation changes the molecule's ability to conduct an electric current, thereby switching among multiple logic states without changing the spherical shape of the carbon cage. Petek says this concept also protects the molecule so it can function without influence from outside chemicals.

Because of their constant spherical shape, the prototype molecular switches can be integrated as atom-like building blocks the size of one nanometer (100,000 times smaller than the diameter of a human hair) into massively parallel computing architectures.

The prototype was demonstrated using an Sc3N@C80 molecule sandwiched between two electrodes consisting of an atomically flat copper oxide substrate and an atomically sharp tungsten tip. By applying a voltage pulse, the equilateral triangle-shaped Sc3N could be rotated predictably among six logic states.

The research was led by Petek in collaboration with chemists at the Leibnitz Institute for Solid State Research in Dresden, Germany, and theoreticians at the University of Science and Technology of China in Hefei, People's Republic of China. The experiments were performed by postdoctoral researcher Tian Huang and research assistant professor Min Feng, both in Pitt's Department of Physics and Astronomy.

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The above story is reprinted from materials provided by University of Pittsburgh.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Tian Huang, Jin Zhao, Min Feng, Alexey A. Popov, Shangfeng Yang, Lothar Dunsch, Hrvoje Petek. A Molecular Switch Based on Current-Driven Rotation of an Encapsulated Cluster within a Fullerene Cage. Nano Letters, 2011; 111123145903006 DOI: 10.1021/nl2028409

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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Digital switch won't kill old habits

Over-the-air broadcasters in Canada will make the switch midnight Wednesday by scrapping an analog signal for digital, but many viewers are doing whatever they can to avoid cable or satellite companies.

Though the change will not affect those who have satellite or cable packages, those who swear by using an antenna to watch TV will not ease their grip on the so-called rabbit ears.

"Too much TV," declared Helen and Walter Last of Poltimore, Que., "There's lots to do in the country."

A west Ottawa storeowner said he is struggling to keep up with the demand on digital antennas.

The trend, he believes, is an anti-corporation, anti-big business attitude amongst consumers.

"Every single antenna was sold within a day and a half," said Jeff Bayly, who runs the Moto-Photo store in Carlingwood Mall, "My supplier can't keep up either."

The obsession with antennas seems to be sweeping those who have ventured to digital cable, too.

Patrick Charette said he is constantly complaining about the high cost of his basic cable package.

"I actually have cable. I'm in the transition of getting rid of it," said Charette.

For those who refuse satellite or cable, the combination of a digital tuner, which most modern televisions have built inside and a decent antenna will serve their purpose quite well.

If viewers do not have that combo, they can buy a separate converter for about $60 that allows them to have 15 to 22 channels for free.

That seems to be a perfect number for many people, as the switch to digital will mean a better signal.

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5 ways the switch to digital TV will affect you

Over-the-air TV signals switch to digital from analog transmission as of Thursday morning in most major cities across Canada. The federal government and the CRTC mandated the change in order to free up broadcast spectrum. Here's how it will affect you.

If you watch television via satellite or cable, you won't be affected. Satellite signals are already digital, while cable providers will continue to transmit the analog channels in their lineups the old way — though it's expected analog cable channels will eventually be phased out.If you watch TV via an antenna or set-top rabbit ears and you live in one of 30 markets (including provincial capitals or cities with more than 300,000 residents), you will need a newer television with a built-in digital tuner, or a converter box that turns the digital broadcast signal into an analog one that older TVs can use.In smaller markets, broadcasters are allowed to continue transmitting analog signals over the air. For the most part, residents won't be affected, though there will be some shifting of channels. Some people are choosing to cancel their subscription to cable or satellite TV, since over-the-air digital broadcasts often have better, or at least equivalent, picture and sound qualityGlobalTV and CTV are converting all their required transmitters to digital by the Wednesday night deadline, but the CBC is not. Unless it receives a further exemption from the CRTC, cities like Saint John, Quebec City, Saskatoon and London, Ont., will lose their free, over-the-air English CBC broadcasts next August, while places such as Calgary and Windsor, Ont., won't get transmissions of French-language Radio-Canada.

Map of Canadian markets required to convert to digital over-the-air TV transmission:

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