Released By: Australian Synchrotron
Release Date: Sun 30 November 2008

Australian researchers are developing better ways to gather accurate information about greenhouse gases in the upper atmosphere with the help of synchrotron infrared light.

In a recent paper in Chemical Physics Letters, they reported on a study that will allow more accurate measurement of an important refrigerant, R152a, which is commonly used in car air-conditioning and industry.

"R152a is a commonly used replacement for the ozone-depleting chlorofluorocarbons used in refrigeration," says the lead author, Monash University chemist Don McNaughton.

"Its levels in the atmosphere have gone up five-fold since it was introduced more than a decade ago, which is a concern as this gas, which absorbs infrared light, is believed to contribute to greenhouse warming," he says.

The study, published this month in the journal Chemical Physics Letters, gave the researchers an accurate picture of the gas using an infrared spectrometer attached to the synchrotron. The system measures the absorbance by the gas of different wavelengths of infrared light and produces a highly detailed spectrum that is characteristic of the gas and its chemical structure.

"The information will help climate scientists improve their models and hence the measurements obtained from high altitude balloons and ground based instruments," says Don.

"The infrared beamline provides new opportunities to do these kinds of experiments," says the Synchrotron's principal infrared beamline scientist Mark Tobin.

"And new equipment being developed for the infrared beamline will extend its capabilities even further, allowing the researchers to reproduce the wide range of temperatures found in the Earth's upper atmosphere - ranging from 20 to minus 90."

The Monash researchers are also planning to study the far infrared spectra of interstellar molecules such as methanimine.

"These molecules only exist for very short times on Earth so we will have some challenges generating them in order to analyse them," Don says. "To enable us to start these experiments the Synchrotron is installing special exhaust systems to safely carry the resultant gas stream away."

The resulting data, he says, will be of great assistance to radio-astronomers studying the composition of interstellar gases.

The study is the second paper to come out of research performed on the infrared beamline since it opened last year.

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