Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Scientists measure soot particles in flight

This is the diffraction pattern of a mixed salt/soot aerosol particle.

Credit: Duane Loh et al.
This is the diffraction pattern of a mixed salt/soot aerosol particle.

Credit: Duane Loh et al.

Abstract:
"For the first time we can actually see the structure of individual aerosol particles floating in air, their 'native habitat'," said DESY scientist Henry Chapman from the Center for Free-Electron Laser Science (CFEL) in Hamburg. "This will have important implications for various fields from climate modelling to human health." CFEL is a joint venture of Deutsches Elektronen-Synchrotron DESY, the German Max Planck Society and the University of Hamburg.

Scientists measure soot particles in flight

Germany | Posted on June 27th, 2012

Aerosol particles like soot play important roles in a wide range of fields from toxicology to climate science. Despite their importance, their properties are surprisingly difficult to measure: Visible light doesn't provide the necessary resolution, X-ray sources are usually not bright enough to image single particles, and for electron microscopy particles have to be collected onto a substrate, which potentially alters their structure and encourages agglomeration.

Using the world's most powerful X-ray laser LCLS at the U.S. SLAC National Accelerator Laboratory in Stanford (California), the team captured images of single soot particles floating through the laser beam. "We now have a richer imaging tool to explore the connections between their toxicity and internal structure," said SLAC's Duane Loh, lead author of the study appearing in this week's scientific journal Nature. Free-electron lasers like LCLS or the European XFEL currently being built in Hamburg consist of particle accelerators that send unbound (free) electrons on a tight slalom course where they emit X-ray light.

The study focused on particles less than 2.5 micrometres in diameter. This is the size range of particles that efficiently transport into the human lungs and constitute the second most important contribution to global warming. Microscopic soot particles were generated with electric sparks from a graphite block and fed with a carrier gas of argon and nitrogen into a device called an aerodynamic lens, that produces a thin beam of air with entrained soot particles. This aerosol beam intercepted the pulsed laser beam. Whenever an X-ray laser pulse hit a soot particle, it produced a characteristic diffraction pattern that was recorded by a detector. From this pattern, the scientists were able to reconstruct the soot particle's structure.

"The structure of soot determines how it scatters light, which is an important part of understanding how the energy of the sun is absorbed by the earth's atmosphere. This is a key factor in models of the earth's climate," explained co-author Andrew Martin from DESY. "There also are many links between airborne particles around two micrometres in size and adverse health effects. Using the free-electron laser we are now able to measure the shape and composition of individual airborne particles. This may lead to a better understanding of how these particles interfere with the function of cells in the lungs."

The team recorded patterns from 174 individual soot particles and measured their compactness, using a property called fractal dimension. "We've seen that the fractal dimension is higher than what was thought," said Chapman. "This means that soot in the air is compact, which has implications for the modelling of climate effects." Also, the structure of the airborne soot seems to be surprisingly variable. "There is quite some variation in the fractal dimension, which implies that a lot of rearrangement is going on in the air," explains Chapman.

A primary long-term goal of the research is to take snapshots of airborne particles as they change their size, shape and chemical make-up in response to their environment, explained Michael Bogan from SLAC, who led the research. "Scientists can now imagine being able to watch the evolution of soot formation in combustion engines from their molecular building blocks, or maybe even view the first steps of ice crystal formation in clouds."

In real-world settings soot is seldom pure. To see the effects of mixing with other aerosols, the researchers added salt spray to the soot particles, resulting in larger particles with soot attached to the tiny salt crystals. Such composite particles might form in coastal cities and are expected to have a much larger climate effect than soot alone. Composite aerosols are more difficult to analyse, but the new technique could clearly discern between soot, salt and mixtures of both. As the aerosol particles are vaporized by the intense X-ray laser pulse, the researchers could use mass spectroscopy to examine the composition of each individual particle imaged.

Even though the aerosol particles are destroyed by the X-ray laser pulse, the pulse is so short that it out-runs this destruction. Therefore the diffraction patterns are of high quality and represent the undamaged object. The novel X-ray technique can find wide application to study all sorts of aerosols and can also be extended to resolve the static and dynamic morphology of general ensembles of disordered particles, the researchers state.

"We are now able to study the structure of soot by measuring individual particles in a large ensemble," explains Martin. "Biological samples, like cells and large proteins, have a similar size to the soot particles we studied and also lack a fixed, reproducible structure. In the future it may be possible to extend these techniques beyond aerosols, to study the structural variations in biological systems."

The research team included contributors from SLAC, DESY, Lawrence Berkeley National Laboratory, the Max Planck Institutes, the National Energy Research Scientific Computing Center, Lawrence Livermore National Laboratory, Cornell University, the University of Hamburg, Synchrotron Trieste and Uppsala University. LCLS is supported by DOE's Office of Science.

####

For more information, please click here

Contacts:
Dr. Thomas Zoufal

49-408-998-1666

Copyright © Helmholtz Association of German Research Centres

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

News and information

Iran to Hold 3rd Int'l Engineering Materials, Metallurgy Conference October 25th, 2014

Haydale Secures Exclusive Development and Supply Agreement with Tantec A/S: New reactors to be built and commissioned by Tantec A/S represent another step forward towards the commercialisation of graphene October 24th, 2014

QuantumWise guides the semiconductor industry towards the atomic scale October 24th, 2014

SUNY Polytechnic Institute Invites the Public to Attend its Popular Statewide 'NANOvember' Series of Outreach and Educational Events October 23rd, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Imaging

National Synchrotron Light Source II Achieves 'First Light' October 23rd, 2014

Laboratories

National Synchrotron Light Source II Achieves 'First Light' October 23rd, 2014

Novel Rocket Design Flight Tested: New Rocket Propellant and Motor Design Offers High Performance and Safety October 23rd, 2014

Govt.-Legislation/Regulation/Funding/Policy

Novel Rocket Design Flight Tested: New Rocket Propellant and Motor Design Offers High Performance and Safety October 23rd, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Brookhaven Lab Launches Computational Science Initiative:Leveraging computational science expertise and investments across the Laboratory to tackle "big data" challenges October 22nd, 2014

Bipolar Disorder Discovery at the Nano Level: Tiny structures found in brain synapses help scientists better understand disorder October 22nd, 2014

Discoveries

QuantumWise guides the semiconductor industry towards the atomic scale October 24th, 2014

Iranian, Malaysian Scientists Study Nanophotocatalysts for Water Purification October 23rd, 2014

Nanoparticle technology triples the production of biogas October 23rd, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Announcements

Iran to Hold 3rd Int'l Engineering Materials, Metallurgy Conference October 25th, 2014

Haydale Secures Exclusive Development and Supply Agreement with Tantec A/S: New reactors to be built and commissioned by Tantec A/S represent another step forward towards the commercialisation of graphene October 24th, 2014

QuantumWise guides the semiconductor industry towards the atomic scale October 24th, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Tools

Haydale Secures Exclusive Development and Supply Agreement with Tantec A/S: New reactors to be built and commissioned by Tantec A/S represent another step forward towards the commercialisation of graphene October 24th, 2014

National Synchrotron Light Source II Achieves 'First Light' October 23rd, 2014

Advancing thin film research with nanostructured AZO: Innovnano’s unique and cost-effective AZO sputtering targets for the production of transparent conducting oxides October 23rd, 2014

NIST offers electronics industry 2 ways to snoop on self-organizing molecules October 22nd, 2014

Photonics/Optics/Lasers

Physicists build reversible laser tractor beam October 20th, 2014

Magnetic mirrors enable new technologies by reflecting light in uncanny ways October 16th, 2014

New VDMA Association "Electronics, Micro and Nano Technologies" founded: Inaugural Meeting in Frankfurt/Main, Germany October 15th, 2014

Nanodevices for clinical diagnostic with potential for the international market: The development is based on optical principles and provides precision and allows saving vital time for the patient October 15th, 2014

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







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE