Three different groups provide new insight into atmospheric reactions.

Three different groups provide new insight into atmospheric reactions.

A transatlantic meeting of minds has led to the updating of key atmospheric chemistry data used by NASA. Three groups of atmospheric chemists, two from the US, and one from the UK, recently discovered that they were all working towards the same goal; the updating of rate coefficients for airborne chemical reactions. In use for the past 20 years, the old data were causing large inaccuracies in measurements of key atmospheric processes, especially the reactions of atomic oxygen, O( 1D), formed from the breakdown of ozone.

All three groups had been independently re-measuring rate coefficients for important reactions of excited O( 1D) with atmospheric gases. The research, led by Dwayne Heard at the University of Leeds, UK, Akkihebbal Ravishankara at the National Oceanic and Atmospheric Administration, Boulder, US, and Paul Wine at the Georgia Institute of Technology, US, used laser flash photolysis to study the reaction kinetics of O( 1D) with a number of gases, including O 2, N 2, H 2 and other greenhouse gases. All three groups found that the new values were up to 20 per cent higher than those currently in use by international bodies such as IUPAC and NASA. Heard was surprised to find out that he was not alone in his discovery: ’We were aware that both [US] groups were measuring rate coefficients of O( 1D) reactions, but did not realise that we [all three] had all measured O( 1D) and atmospheric gases . and more interestingly, that all three of us were in agreement with the new and higher value for O( 1D) reactions with N 2’.

Commenting on the importance of the work, John Crowley from the atmospheric chemistry department of the Max-Planck-Institut für Chemie in Mainz, Germany, says ’the reaction of O( 1D) with N 2 is one of the most important in the atmosphere. Knowledge of the rate coefficient for this reaction is central to our understanding of the chemistry of ozone throughout the atmosphere . The new results from these three papers have shown us that even some of the most important atmospheric gas-phase processes are still associated with uncertainties that are unnecessarily large. Reducing this uncertainty is a challenge that can only be met by the application of modern instrumentation and appropriate laboratory expertise. These studies are prime examples of how this can be achieved when a critical mass of expertise can be focused onto a single theme’.

Katharine Sanderson

References

R S Strekowski, J M Nicovich and P H Wine, Phys. Chem. Chem. Phys., 2004 (DOI: 10.1039/  <MAN>b400243a</MAN>)

E J Dunlea and A R Ravishankara, Phys. Chem. Chem. Phys., 2004 (DOI: 10.1039/ <MAN>b400247d</MAN>)

M A Blitz et al, Phys. Chem. Chem. Phys., 2004 (DOI: 10.1039/ <MAN>b400283k</MAN>)