SCIENCE EXPERIMENT: Researchers finally observed in action so-called Criegee biradicals--a molecule that can clean up pollution in the atmosphere.
Image: Sandia National Laboratories
An international research team has tracked down and measured an elusive molecule that rapidly breaks down pollution in the atmosphere, turning it into clouds that actually help cool the Earth.
The compound is part of a class of molecules called "Criegee biradicals," named after the scientist Rudolf Criegee, who predicted their existence in 1949. The biradicals are intermediates in reactions, meaning they are steppingstones in processes where one compound becomes another.
In this case, they form naturally as ozone -- a high-energy oxygen molecule -- reacts with carbon chains that have double bonds, forming a compound that has two reactive pairs of electrons. The intermediates have high energies and are unstable, reacting quickly with other molecules, making them difficult to analyze.
Previously, if you wanted to study Criegee biradicals and how they reduce sulfur dioxide and nitrogen dioxide pollution in the atmosphere or how they make hydrocarbons spontaneously ignite, you had to do it with indirect measurements and observations.
But researchers at Sandia National Laboratories, partnering with scientists at the University of Manchester and the University of Bristol in the United Kingdom, not only have caught a glimpse of the molecule, but have observed it in action. With this knowledge, researchers can develop better climate models and improve fuel combustion efficiency.
"Almost everyone who dealt with them knew they existed. We discovered a way to make much more concentrated samples of Criegee intermediates. Because of that, now we can study measure the rates of the chemical reactions," said David Osborn, a combustion chemist at Sandia. He explained that his team initially detected Criegee intermediates in 2008 but didn't produce enough of them to see how they interacted with other compounds.
Caught in a powerful pulse of light
Using some new tricks, the researchers made enough Criegee molecules to see how fast they react. They created the biradical, carbonyl oxide, by bombarding diiodomethane with ultraviolet photons in a process known as photolysis.
To ensure that they found molecule they were looking for, the scientists measured the product's mass using a mass spectrometer. However, that only tells you that you have the right number and kinds of atoms in the molecule, not how they are arranged. Compounds with the same composition but different arrangements are called isomers.
Resolving the structure required the use of the Advanced Light Source at Lawrence Berkeley National Laboratory. The device is a synchrotron, a circular particle accelerator, and by shooting electrons around its ring near the speed of light, it generates X-rays and ultraviolet rays that are a billion times brighter than the sun. The light can also be precisely tuned to specific wavelengths, and when it strikes a compound, it causes it to develop a charge. This is called photoionization.
In these circumstances, different structures produce different signals, and by a process of elimination, the team concluded they had found a Criegee biradical. "We backed it up by doing calculations for ionization energy. The calculations agreed very well with our experiments and disagreed with all the other isomers," said Osborn.
Turning greenhouse gases into cooling aerosols
The team then mixed the intermediates with various compounds, like sulfur and nitrogen greenhouse gases, to see how fast they reacted. "The most important thing we found is that they react an awful lot faster than we predicted," said Carl Percival at the University of Manchester School of Earth, Atmospheric and Environmental Sciences.
He explained that the intermediates turn certain greenhouse gases into aerosols, which help form clouds that have a net cooling effect on the planet.
The findings will help researchers create better climate models, but Percival thinks Criegee biradicals cannot feasibly be used to lower temperatures.
"I don't think it's a geoengineering candidate, because it's already part of the Earth's system," he said. "When you make it in the lab, it falls apart. You can't exactly make a whole barrel of it and shove it up in the atmosphere."
The scientists said they will now look for Criegee intermediates in other processes. "The Criegee intermediates themselves are not new, but our understanding of them is much greater, and our understanding of autoignition chemistry and atmospheric chemistry is much greater," said Osborn.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500
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9 Comments
Add Comment"The findings will help researchers create better climate models, but Percival thinks Criegee biradicals cannot feasibly be used to lower temperatures."
Reply | Report Abuse | Link to thisSo I don't want to see ANY comments chuckling about how global warming is over or that since climate scientists don't know EVERYTHING, then they can't know ANYTHING. This is an Argument from Ignorance and is a big-time logical fallacy:
http://en.wikipedia.org/wiki/Argument_from_ignorance
You do not want comment. Who the hell do you think you are? Pope of AGW?
Reply | Report Abuse | Link to this@Carlyle - I agree that sault may have been able to state his request a little more politely, but seriously dude. He specifically asked people to withhold comments that contains serious logical fallacies. Not all comments. Do you understand the difference? And what does this have to do with AGW? I heard this same logic used over and over again, about everything from evolution to cosmology.
Reply | Report Abuse | Link to thisWhere have you been? Everything he posts is about AGW.
Reply | Report Abuse | Link to thisHe panics if there is any hint of a flaw in his obsession & there are many. This is not necessarily one of them.
The (UK) Daily Mail has already done exactly what Sault warned us against, and worse. Their headline (13 January) reads:
Reply | Report Abuse | Link to thisNewly discovered molecule 'could reverse global warming'
The very opposite of what the scientists involved actually think, and, worse, framed to look like a quotation.
Maybe they could launch balloons, with double-bond carbon compounds, into the upper atmosphere. These could use solar power to manufacture Criegee biradicals, in situ, from ambient ozone and those carbon compounds. When the carbon supply runs out, the balloons can fall to earth and be retrieved to be reloaded and sent up again.
Reply | Report Abuse | Link to thisJust a thought. Can anyone provide some more details about how this might work? I'm a computer programmer, not a chemist.
It's obvious now that scientists don't understand even some of the basic physics involved in the AGW hypothesis. These findings may also help explain why there is a disconnect between the computer models and what happens in the real world.
Reply | Report Abuse | Link to thisWith more knowledge, scientists may someday be able to make useful, testable, falsifiable,experimentally sound predictions about the climate, but that day is off in the future.
There is already a natural process that removes sulphur dioxide and nitrogen dioxide pollution from the atmosphere. It is called rain.
Reply | Report Abuse | Link to thisWhy comment at all when you know you are prejudicially misinformed and willfully ignorant on the subject?
Reply | Report Abuse | Link to thisOh yeah, because you are a Right Wing Troll..
Go away.