Inelastic scattering of hydroxyl radicals with helium and argon by velocity-map imaging

ABSTRACT The hydroxyl radical (OH) is one of the most interesting molecules in molecular dynamics. In particular, inelastic collisions of free radicals such as OH are profoundly important in

environments ranging from combustion to astrochemistry. However, measuring the velocities of OH molecules in specific internal quantum states has proven to be very difficult. A method that

can provide this important information is velocity-map imaging. Although this technique is very widely applicable in principle, it does require a sensitive and selective laser-ionization

scheme. Here we show that, under the right conditions, velocity-map imaging can be applied to the study of the inelastic scattering of OH using crossed-molecular-beam methods. We measure

fully quantum-state-specified product angular distributions for OH collisions with helium and argon. The agreement between exact close-coupling quantum scattering calculations on _ab initio_

potential energy surfaces and experimental data is generally very satisfactory, except for scattering in the most forward directions. Access through your institution Buy or subscribe This

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supported by the Netherlands NWO-CW project 700.58.029, the Dutch Astrochemistry Network, and the EU-ITN Network ‘ICONIC’ 238671. S. Marinakis was supported by EPSRC (UK) and the British

Council–Platform Bèta Techniek Programme in Science. K.G.M. was supported by EPSRC (UK). S. Marinakis thanks S. Cybulski and J. Kłos for providing the HeOH/ArOH PES, J. Kłos for many useful

discussions and suggestions, B.J. Howard (Oxford) and F.J. Aoiz (Madrid) for encouraging discussions, and the use of the Oxford Supercomputing Centre in carrying out this work. AUTHOR

INFORMATION AUTHORS AND AFFILIATIONS * Institute for Molecules and Materials, Radboud University Nijmegen, Heijendaalseweg 135, Nijmegen, 6525 ED, The Netherlands Gautam Sarma, Sarantos

Marinakis, J. J. ter Meulen & David H. Parker * Department of Chemistry, The Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK

Sarantos Marinakis * Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK Kenneth G. McKendrick Authors * Gautam Sarma

View author publications You can also search for this author inPubMed Google Scholar * Sarantos Marinakis View author publications You can also search for this author inPubMed Google

Scholar * J. J. ter Meulen View author publications You can also search for this author inPubMed Google Scholar * David H. Parker View author publications You can also search for this author

inPubMed Google Scholar * Kenneth G. McKendrick View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS D.H.P., J.J.tM. and K.G.M. supervised the

project and designed the experiments. G.S. performed the VMI experiments and collected and analysed the data with assistance from S.M., who performed the quantum calculations with assistance

in interpretation from K.G.M. G.S. and D.H.P. wrote the manuscript with significant input from J.J.tM., S.M. and K.G.M. CORRESPONDING AUTHOR Correspondence to David H. Parker. ETHICS

DECLARATIONS COMPETING INTERESTS The authors declare no competing financial interests. SUPPLEMENTARY INFORMATION SUPPLEMENTARY INFORMATION Supplementary information (PDF 819 kb) RIGHTS AND

PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Sarma, G., Marinakis, S., ter Meulen, J. _et al._ Inelastic scattering of hydroxyl radicals with helium and argon by

velocity-map imaging. _Nature Chem_ 4, 985–989 (2012). https://doi.org/10.1038/nchem.1480 Download citation * Received: 14 June 2012 * Accepted: 20 September 2012 * Published: 28 October

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