Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Special UO microscope captures defects in nanotubes

22.10.2014

University of Oregon chemists provide a detailed view of traps that disrupt energy flow, possibly pointing toward improved charge-carrying devices

University of Oregon chemists have devised a way to see the internal structures of electronic waves trapped in carbon nanotubes by external electrostatic charges.


George Nazin, a professor of physical chemistry at the University of Oregon, has uncovered traps, or defects, that disrupt electronic waves in nanotubes. The work was done with a scanning tunneling microscope fitted with a closed-cycle cryostat.

Credit: University of Oregon

Carbon nanotubes have been touted as exceptional materials with unique properties that allow for extremely efficient charge and energy transport, with the potential to open the way for new, more efficient types of electronic and photovoltaic devices. However, these traps, or defects, in ultra-thin nanotubes can compromise their effectiveness.

Using a specially built microscope capable of imaging matter at the atomic scale, the researchers were able to visualize traps, which can adversely affect the flow of electrons and elementary energy packets called excitons.

The study, said George V. Nazin, a professor of physical chemistry, modeled the behavior often observed in carbon nanotube-based electronic devices, where electronic traps are induced by stochastic external charges in the immediate vicinity of the nanotubes. The external charges attract and trap electrons propagating through nanotubes.

"Our visualization should be useful for the development of a more accurate picture of electron propagation through nanotubes in real-world applications, where nanotubes are always subjected to external perturbations that potentially may lead to the creation of these traps," he said.

The research, detailed in a paper in the Journal of Physical Chemistry Letters, was done with an ultra-high vacuum scanning tunneling microscope coupled to a closed-cycle cryostat -- a novel device built for use in Nazin's lab. The cryostat allowed Nazin and his co-authors Dmitry A. Kislitsyn and Jason D. Hackley, both doctoral students, to lower the temperature to 20 Kelvin to freeze all nanoscale motion, and visualize the internal structures of nanoscale objects.

The device captured the internal structure of electronic waves trapped in short sections, just several nanometers long, of nanotubes partially suspended above an atomically flat gold surface. The properties of the waves, to a large extent, Nazin said, determine electron transmission through such electronic traps. The propagating electrons have to be in resonance with the localized waves for efficient electronic transmission to occur.

"Amazingly, by finely tuning the energies of propagating electrons, we found that, in addition to these resonance transmission channels, other resonances also are possible, with energies matching those of specific vibrations in carbon nanotubes," he said. "These new transmission channels correspond to 'vibronic' resonances, where trapped electronic waves excite vibrations of carbon atoms forming the electronic trap."

The microscope the team used is detailed separately in a freely available paper (High-stability cryogenic scanning tunneling microscope based on a closed-cycle cryostat) placed online Oct. 7 by the journal Review of Scientific Instruments.

###

The National Science Foundation (grant DMR-0960211) and a grant from the Oregon Nanoscience and Microtechnologies Institute (ONAMI) supported the construction of the microscope used in the project.

Nazin's co-authors on the paper detailing the microscope are Hackley, Kislitsyn, former UO doctoral student Daniel K. Beaman, now at Intel Corp. in Hillsboro, Oregon, and Stefan Ulrich of RHK Technologies Inc. in Troy, Michigan.

Source: George Nazin, assistant professor of physical chemistry, 541-346-2017, gnazin@uoregon.edu

Note: The University of Oregon is equipped with an on-campus television studio with a point-of-origin Vyvx connection, which provides broadcast-quality video to networks worldwide via fiber optic network. In addition, there is video access to satellite uplink, and audio access to an ISDN codec for broadcast-quality radio interviews.

Links:

About Nazin: http://chemistry.uoregon.edu/profile/gnazin/

Department of Chemistry and Biochemistry: http://chemistry.uoregon.edu/

JPCL paper: http://pubs.acs.org/doi/abs/10.1021/jz5015967

Paper on microscope: http://scitation.aip.org/content/aip/journal/rsi/85/10/10.1063/1.4897139

Jim Barlow | Eurek Alert!

More articles from Life Sciences:

nachricht Warming ponds could accelerate climate change
21.02.2017 | University of Exeter

nachricht An alternative to opioids? Compound from marine snail is potent pain reliever
21.02.2017 | University of Utah

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>