Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > 'We're down to the atom size'

Abstract:
Cornell researchers discover how to focus on tiniest of the very small

'We're down to the atom size'

Posted on June 14, 2006

By Lauren Gold
lg34@cornell.edu

If you need a good picture of a molecule, your first job is getting its atoms to pose for you, says John Silcox, Cornell's David E. Burr Professor of Engineering and an expert in the realm of the very tiny.

But atoms are not willing subjects. They jiggle furiously, defying any microscopist who tries to catch them at a standstill. Nor are they polite: The larger atoms in a molecule typically overshadow the smaller ones, making it impossible to view the little ones.

Now, though, researchers at Cornell have developed a technique to get a closer-than-ever look at individual atoms within crystal molecules -- allowing them, for the first time, to see the polarity, or physical alignment, of those constituent atoms and to get a view of the smaller atoms.

The research -- by Cornell postdoctoral associate K. Andre Mkhoyan, Silcox and colleagues at Cornell, and Philip Batson of IBM -- is described in the June 2 issue of Science.

With the new technique, researchers can better predict the physical properties of a crystal at every point -- an advance that offers potential improvements in lasers and other devices, particularly at the nanoscale, where the structure of an individual molecule can determine a device's behavior.

To get their new and improved view, Mkhoyan's team used a scanning transmission electron microscope (STEM) at IBM on samples of aluminum nitride, gallium nitride and other crystals with particular significance in nanotechnology research, in a chamber padded and shielded to reduce potentially atom-jiggling acoustic noise and electromagnetic radiation. Fitting the STEM with an aberration corrector (a focusing device) developed at Nion Co., they directed a 0.9 angstroms-wide electron beam at tiny crystal samples, collecting the scattered electrons on a ring-shaped detector and forming an image based on the resulting scatter pattern. (An angstrom is one hundred-millionth of a centimeter). Because larger atoms deflect electrons at a larger angle than small ones, the resulting data is relatively simple to interpret.

Used on a sample of aluminum nitride, the technique, called annular dark imaging, shows pear-shaped molecule columns with the larger aluminum atoms at the thicker end and the smaller nitrogen atoms at the narrower end. It is the first time the smaller atoms in such a structure have been caught in an image.

The key, said Silcox, is the narrowness of the scanning electron beam.

"We're down to the atom size, as opposed to the atom spacing," said Silcox. "We can start to see the light atom columns; we can characterize the crystal very nicely and precisely, at every place on the structure."

Mkhoyan said the inability to capture such images in the past has been a huge hurdle for nanotechnology researchers.

"The study and application of these lattice crystals are at the core of nanotechnology. Many papers are dedicated to synthesis and application of the nanoparticles -- quantum dots, rods, wires, you name it -- based on these materials," he said. "However, the performance of the devices is highly dependent on the structural quality of these nanoparticles.

"With our STEM annular dark field imaging, we come to the rescue," Mkhoyan added. "We can zoom in, pick up any region of the structure, and see how it behaves."

####

Contact:
Cornell University News Service/Chronicle Online
312 College Ave.
Ithaca, NY 14850
607.255.4206
cunews@cornell.edu

Copyright Cornell University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Materials/Metamaterials

Assembly of nanoparticles proceeds like a zipper: Viruses and nanoparticles can be assembled into processable superlattice wires according to scientists from Aalto University Finland September 25th, 2017

Copper catalyst yields high efficiency CO2-to-fuels conversion: Berkeley Lab scientists discover critical role of nanoparticle transformation September 20th, 2017

New quantum phenomena in graphene superlattices September 18th, 2017

New insights into nanocrystal growth in liquid: Understanding process that creates complex crystals important for energy applications September 14th, 2017

Announcements

Assembly of nanoparticles proceeds like a zipper: Viruses and nanoparticles can be assembled into processable superlattice wires according to scientists from Aalto University Finland September 25th, 2017

Enhancing the sensing capabilities of diamonds with quantum properties: A simple method can give diamonds the special properties needed for quantum applications such as sensing magnetic fields September 24th, 2017

Quantum twisted Loong confirms the physical reality of wavefunctions September 23rd, 2017

Application of air-sensitive semiconductors in nanoelectronics: 2-D semiconductor gallium selenide in encapsulated nanoelectronic devices September 22nd, 2017

Tools

Graphene based terahertz absorbers: Printable graphene inks enable ultrafast lasers in the terahertz range September 13th, 2017

Chemical hot spots: Scanning tunneling microscopy measurements identify active sites on catalyst surfaces September 7th, 2017

Phenom-World selects Deben to supply a tensile stage as an accessory to their range of desktop SEMs August 29th, 2017

New results reveal high tunability of 2-D material: Berkeley Lab-led team also provides most precise band gap measurement yet for hotly studied monolayer moly sulfide August 26th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project