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Scattering of hydroxyl radicals measured with velocity-map imaging
30 October 2012
Research on inelastic scattering of hydroxyl radicals, examined with velocity-map imaging at Radboud University Nijmegen, has made the cover of Nature Chemistry. The article by David Parker and coworkers of the Institute for Molecules and Materials (IMM) can already be read online.
Hydroxyl radicals (OH) are important in many chemical systems, including combustion and atmospheric reactions. Measuring experimentally the speed and direction of travel of OH with specific forms of internal energy (e.g. rotational, vibrational and electronic energy) has proved difficult. However, measuring these aspects is a key diagnostic of the mechanism of the process that formed OH.
Now, these distributions (the state-to-state differential cross sections) for inelastic scattering of fully state-specified OH with He and Ar have been measured for the first time. This has been made possible by exploiting the velocity-map imaging technique in a crossed molecular-beam arrangement. The velocity-map imaging technique was invented at the Radboud University Nijmegen in 1997 by David Parker and coworkers.
The measured speed and angular distributions are shown to compare favorably with theoretical predictions. This confirms the quality of calculated potential energy surfaces that are used to describe the astrochemically relevant collisions of OH with He.
More information on the technique of velocity-map imaging: http://www.ru.nl/ccc/@836188/pagina/