Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Physicist's innovative technique makes atomic-level microscopy at least 100 times faster

University Photography

Cornell Professor Keith Schwab works on a low-temperature apparatus similar to that used in the paper reported in this weeks issue of Nature.
University Photography
Cornell Professor Keith Schwab works on a low-temperature apparatus similar to that used in the paper reported in this weeks issue of Nature.

Abstract:
Using an existing technique in a novel way, Cornell physicist Keith Schwab and colleagues at Cornell and Boston University have made the scanning tunneling microscope (STM) -- which can image individual atoms on a surface -- at least 100 times faster.

Physicist's innovative technique makes atomic-level microscopy at least 100 times faster

ITHACA, NY | Posted on October 31st, 2007

The simple adaptation, based on a method of measurement currently used in nano-electronics, could also give STMs significant new capabilities -- including the ability to sense temperatures in spots as small as a single atom, and to detect changes in position as tiny as 0.00000000000001 meters: a distance 30,000 times smaller than the diameter of an atom.

The finding is described in the Nov. 1 issue of the journal Nature.

The STM uses quantum tunneling, or the ability of electrons to "tunnel" across a barrier, to detect changes in the distance between a needlelike probe and a conducting surface. Researchers apply a tiny voltage to the sample and move the probe -- a simple platinum-iridium wire snipped to end in a point just one atom wide -- just a few angstroms (10ths of a nanometer) over the sample's surface. By measuring changes in current as electrons tunnel between the sample and the probe, they can reconstruct a map of the surface topology down to the atomic level.

Since its invention in the 1980s, the STM has enabled major discoveries in fields from semiconductor technology to nano-electronics.

But while current can change in a nanosecond, measurements with the STM are painfully slow. And the limiting factor is not in the signal itself: It's in the basic electronics involved in analyzing it. A theoretical STM could collect data as fast as electrons can tunnel -- at a rate of one gigahertz, or 1 billion cycles per second of bandwidth. But a typical STM is slowed down by the capacitance, or energy storage, in the cables that make up its readout circuitry -- to about one kilohertz (1,000 cycles per second) or less.

Researchers have tried a variety of complex remedies. But in the end, said Schwab, an associate professor of physics at Cornell, the solution was surprisingly simple. By adding an external source of radio frequency (RF) waves and sending a wave into the STM through a simple network, the researchers showed that it's possible to detect the resistance at the tunneling junction -- and hence the distance between the probe and sample surface -- based on the characteristics of the wave that reflects back to the source.

The technique, called reflectometry, uses the standard cables as paths for high-frequency waves, which aren't slowed down by the cables' capacitance.

"There are six orders of magnitude between the fundamental limit in frequency and where people are operating," said Schwab. With the RF adaptation, speeds increase by a factor of between 100 and 1,000. "Our hope is that we can produce more or less video images, as opposed to a scan that takes forever."

The setup also offers potential for atomic resolution thermometry -- precise measurements of temperature at any particular atom on a surface -- and for motion detection so sensitive it could measure movement of a distance 30,000 times smaller than the size of an atom.

"This STM will be used for a lot of good physics experiments," said Schwab. "Once you open up this new parameter, all this bandwidth, people will figure out ways to use it. I firmly believe 10 years from now there will be a lot of RF-STMs around, and people will do all kinds of great experiments with them."

The research was supported by the National Science Foundation.

####

For more information, please click here

Contacts:
Lauren Gold
(607) 255-9736


Press Relations Office
(607) 255-6074

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

Discoveries

Personal cooling units on the horizon April 29th, 2016

Exploring phosphorene, a promising new material April 29th, 2016

Nanoparticles hold promise as double-edged sword against genital herpes April 28th, 2016

Researchers create a first frequency comb of time-bin entangled qubits: Discovery is a significant step toward multi-channel quantum communication and higher capacity quantum computers April 28th, 2016

Announcements

Personal cooling units on the horizon April 29th, 2016

Exploring phosphorene, a promising new material April 29th, 2016

Arrowhead Pharmaceuticals Files for Regulatory Clearance to Begin Phase 1/2 Study of ARC-521 April 28th, 2016

The Translational Research Center at the University Hospital of Erlangen in Germany uses the ZetaView from Particle Metrix to quantify extracellular vesicles such as exosomes April 28th, 2016

Tools

Exploring phosphorene, a promising new material April 29th, 2016

JPK reports on the use of a NanoWizard AFM system at the University of Kaiserslautern to study the interaction of bacteria with microstructured surfaces April 28th, 2016

Chemists use DNA to build the world's tiniest thermometer April 27th, 2016

Bruker Introduces Dimension FastScan Pro Industrial AFM: Providing Nanometer-Resolution at High Scan Rates for up to 300-mm Samples April 26th, 2016

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







Car Brands
Buy website traffic