Dr K H Hughes

School of Natural Sciences, Bangor University, Bangor, Gwynedd, Wales, LL57 2UW, UK

Professor M Fromhold

School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK

Dr A Emmanouilidou

Department of Physics and Astronomy, University College London, London WC1E 6BT, UK

Dr D Dundas

School of Mathematics and Physics, The Queen’s University of Belfast, Belfast, BT7 1NN, UK

Professor A J Daley

Department of Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow East, Glasgow, G4 0NG, UK