OFFICERS AND COUNCIL OF THE FARADAY DIVISION 1994-95 President Prof. J. P. Simons (Oxford) Vice- Presidents who haw held office as President Prof. A. D. Buckingham (Cambridge) Prof. R. Parsons (Southampton) Prof. P. Gray (Cambridge) Prof. N. Sheppard (Norwich) Prof. R. H. Ottewill (Bristol) Vice -Presidents Prof. A. Carrington (Southampton) Prof. M. W. Roberts (Cardiff) Prof. M. A. Chesters (Nottingham) Prof. I. W. M. Smith (Birmingham) Prof. R. N. Dixon (Bristol) Prof. F. S. Stone (Bath) Prof. M. J. Pilling (Leeds) Ordinary Members Dr. 0. C. Clary (Cambridge) Prof. D. A. Parkes (Chester) Prof. P. W. Fowler (Exeter) Dr. S. L. Price (London) Prof. A. Hamnett (Newcastle) Prof. S. K. Scott (Leeds) Prof. J. Lyklema (Wageningen) Prof. A. J. Stace (Sussex) Dr.W. Mackrodt (St. Andrews) Prof. Sir John Meurig Thomas (London) Honorary Secretary Prof. M. J. Pilling (Leeds) Honorary Treasurer Prof. F. S. Stone (Bath) Secretary Mrs. Y. A. Fish Faraday Editorial Board Prof. M. N. R. Ashfold (Bristol) (Chairman) Prof. A. R. Hillman (Leicester) Prof. J. A. Beswick (Paris) Dr. J. Holzwarth (Berlin) Dr. D. C. Clary (Cambridge) Prof. D. Langevin (Bordeaux) Dr. L. R. Fisher (Bristol) Prof. S. K. Scott (Leeds) Prof. B. E. Hayden (Southampton) Dr. R. K. Thomas (Oxford) Prof. J. S. Higgins (London) Scientific Editor Prof. A. R. Hillman Managing Editor Dr. R. A. Whitelock Production Editor Mrs. S. Shah Assistant Production Editor Dr. J. C. Thorn The Faraday Divisionof the Royal Society of Chemistry,previously The Faraday Society founded in 1903 to promote the study of Sciences lying between Chemistry Physics and Biology Faraday Discussions (ISSN 0301-7249) is published triannually by the Royal Society of Chemistry Thomas Graham House Science Park Milton Road Cambridge CB4 4WF England.1995 Annual subscription rate EC €207.00 Rest of World €217.00 USA $380.00 including air-speeded delivery Canada €217 + GST. Change of address and orders with payment in advance to The Royal Society of Chemistry Turpin Distribution Services Ltd. Blackhorse Road Letchworth Herts SG6 lHN UK. NB Turpin Distribution Services Ltd. is wholly owned by the Royal Society of Chemistry. Customers should make payments by cheque in sterling payable on a UK clearing bank or in US dollars payable on a US clearing bank. Air freight and mailing in the USA by Publications Expediting Inc. 200 Meacham Avenue Elmont NY 1103. Second class postage paid at Jamaica NY 11431. USA Postmaster send address changes to Furday Discussions Publications Expediting Inc. 200 Meacham Avenue Elmont NY 11003. All other despatches outside the UK by Bulk Airmail within Europe Accelerated Surface Post outside Europe. PRINTED IN THE UK. 0The Royal Society of Chemistry 19%. All rights reserved. No part of this publication may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photographic recording or otherwise without prior permission of the publishers.