Featured Research

from universities, journals, and other organizations

Nanoswitches Toggled By Light

Date:
March 7, 2008
Source:
Wiley-Blackwell
Summary:
Microscopic fissures in a tiny crystal open and close—on command. Researchers have successfully used an ultrafast electron microscopy to observe switchable nanochannels, which could be useful for future nanoelectronics and nanoscopic "machines."

Microscopic fissures in a tiny crystal open and close—on command. Researchers led by Ahmed H. Zewail successfully used ultrafast electron microscopy (UEM) to observe nanoscopic structures at their “exercises”, as they report in the journal Angewandte Chemie. Such switchable nanochannels could be useful for future nanoelectronics and nanoscopic “machines”.

Zewail and his team at the California Institute of Technology (Pasadena, USA) are renowned for their work in ultrafast science and technology. Zewail received the Nobel Prize in Chemistry in 1999 for the development of ultrafast laser techniques that are capable of revealing the motions of individual atoms within a molecule during a reaction. The most recent development to spring from Zewail’s Laboratory is ultrafast electron microscopy. This technique is a combination of a femtosecond optical system (a femtosecond equals 10-15 seconds) with a high-resolution electron microscope; the result is a new tool with extremely high resolution in time as well as in space.

Zewail and his team have now discovered that needle-shaped microcrystals of copper and the organic compound TCNQ (7,7,8,8-tetracyanoquinodimethane, C12H4N4 ), a crystalline, quasi-one-dimensional semiconductor, exhibit optomechanical phenomena that could be of use in nanoelectronic applications. The investigation showed that these crystals stretch out to become longer (but not wider) when they are irradiated with laser pulses in the microscope.

If the irradiation is switched off, they contract back to their original size. This effect was most obvious when one of these needles was broken by the shock of a short, strong laser pulse: A small crack of some ten to one hundred nanometers forms at the break. When the crystal is stretched out under irradiation, the nanoscale channel closes up; upon contraction, it reappears. The phenomenon is reversible, as confirmed by UEM.

Why do these micromaterials stretch under light? Within the crystal, the negatively charged TCNQ ions are arranged so that their central, flat, six-membered rings are piled up on top of each other in the long direction of the needle. The energy of a laser pulse excites electrons; part of this energy is transferred, resulting in uncharged TCNQ molecules. For the uncharged TCNQ, the stacked arrangement is no longer favorable, they now require more space and cause the crystal to grow longer. The degree of stretching depends on the strength of the energy absorbed.

“Our fundamental in situ UEM observations, which reveal the behavior of nanoscopic matter in space and time, opens up new areas to explore, especially in materials science, nanotechnology, and biology,” says Zewail.

Journal reference: Controlled Nanoscale Mechanical Phenomena Discovered with Ultrafast Electron Microscopy. Angewandte Chemie International Edition 2007, 46, 9206–9210. doi: 10.1002/anie.200704147


Story Source:

The above story is based on materials provided by Wiley-Blackwell. Note: Materials may be edited for content and length.


Cite This Page:

Wiley-Blackwell. "Nanoswitches Toggled By Light." ScienceDaily. ScienceDaily, 7 March 2008. <www.sciencedaily.com/releases/2008/03/080305104850.htm>.
Wiley-Blackwell. (2008, March 7). Nanoswitches Toggled By Light. ScienceDaily. Retrieved September 18, 2014 from www.sciencedaily.com/releases/2008/03/080305104850.htm
Wiley-Blackwell. "Nanoswitches Toggled By Light." ScienceDaily. www.sciencedaily.com/releases/2008/03/080305104850.htm (accessed September 18, 2014).

Share This



More Matter & Energy News

Thursday, September 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Stocks Hit All-Time High as Fed Holds Steady

Stocks Hit All-Time High as Fed Holds Steady

AP (Sep. 17, 2014) The Federal Reserve signaled Wednesday that it plans to keep a key interest rate at a record low because a broad range of U.S. economic measures remain subpar. Stocks hit an all-time high on the news. (Sept. 17) Video provided by AP
Powered by NewsLook.com
Space Race Pits Bezos Vs Musk

Space Race Pits Bezos Vs Musk

Reuters - Business Video Online (Sep. 16, 2014) Amazon CEO Jeff Bezos' startup will team up with Boeing and Lockheed to develop rocket engines as Elon Musk races to have his rockets certified. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
MIT's Robot Cheetah Unleashed — Can Now Run, Jump Freely

MIT's Robot Cheetah Unleashed — Can Now Run, Jump Freely

Newsy (Sep. 16, 2014) MIT developed a robot modeled after a cheetah. It can run up to speeds of 10 mph, though researchers estimate it will eventually reach 30 mph. Video provided by Newsy
Powered by NewsLook.com
Manufacturer Prints 3-D Car In Record Time

Manufacturer Prints 3-D Car In Record Time

Newsy (Sep. 15, 2014) Automobile manufacturer Local Motors created a drivable electric car using a 3-D printer. Printing the body only took 44 hours. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins