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 'Y' a protein unicorn might matter in glaucoma
23.10.2017 | Georgia Institute of Technology

nachricht Microfluidics probe 'cholesterol' of the oil industry
23.10.2017 | Rice University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>