Methods Of Experimentul Physics Molecular Physics

Methods of Experimentul Physics VOLUME 3 MOLECULAR PHYSICS METHODS OF EXPERIMENTAL PHYSICS: L. Marton, Editor-in-Chief Claire Marton, Assistant Editor 1. Classical Methods, 1959 Edited by lmmanuel Estermann 2. Electronic Methods €dited by E. Bleuler and R. 0. Haxby 3. Molecular Physics, 1962 Edited by Dudley Williams 4. Atomic and Electron Physics Edited by Vernon W. Hughes and Howard L. Schultz 5. Nuclear Physics (in two parts), 1961 and 1962 Edited by Luke C. L. Yuan and Chien-Shiung Wu 6. Solid State Physics (in fwo parts), 1959 Edited by K. Lark-Horovitz and Vivian A. Johnson Volume 3 Molecular Physics €dited by DUDLEY W I LLlAMS Ohio Sfate University Columbus, Ohio 1962 ACADEMIC PRESS @ New York and London Copyright @ 1962, by ACADEMIC PRESS INC. ALL RIGHTS RESERVED NO PART OF THIS BOOK MAY B E REPRODUCED I N ANY FORM BY PHOTOSTAT, MICROFILM, OR ANY OTHER MEANS, WITHOUT WRITTEN PERMISSION FROM T H E PUBLISHERS ACADEMIC PRESS INC. 111 FIFTHAVENUE NEW YOEE3, N. Y. United Kingdom Edition Publiehed by ACADEMIC PRESS INC. (LONDON) LTD. 17 OLD QUEENSTREET,LONDON S.W. 1 Library of Congress Catalog Card Number 59-7686 PRINTED I N THE UNITED STATES O F AMERICA CONTRIBUTORS ROYS. ANDERSON, Department of Physics, Clark University, Worcester, Massachusetts R. A. ERICKSON, Department of Physics, Ohio State University, Columbus, Ohio P. M. HARRIS,Department of Chemistry, Ohio State University, Columbus, Ohio ROBERTLAGEMANN, Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee RALPHLIVINGSTON, Chemistry Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee C. A. MCDOWELL, Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada ALVIN H. NIELSEN,Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee SIDNEYREED,O f i e of Naval Research, Washingtoti, D.C. G. WILSEROBINSON, Gates and Crellin Laboratories of Chemistry, California Institute of Technology, Pasadena, California F. D. SHIELDS,Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee DEFORESTSMITH,Oak Ridge Gaseous Diffusion Plant, Union Carbide Nuclear Company, Oak Ridge, Tennessee B. P. STOICHEFF, Division of Pure Physics, National Research Council of Canada, Ottawa, Canada JOHN W. TRISCHKA, Syracuse University, Syracuse, New York T. L. WEATHERLY, School of Physics, Georgia Institute of Technology, Atlanta, Georgia DUDLEY WILLIAMS, Department of Physics, Ohio State University, Columbus, Ohio QUITMAN WILLIAMS, School of Physics, Georgia Institute of Technology, Atlanta, Georgia J. R. ZIMMERMAN, Socony Mobil Oil Company, Inc., Field Research Laboratory, Dallas, Texas V This Page Intentionally Left Blank FOREWORD With the presentation of this volume on molecular physics we reach just about the half-way mark in the publication of our series on experimental physics. This occasion gives me a chance to review briefly the present status of the whole series and the expectations for finishing the job. First of all the companion volume to Nuclear Physics, 5A, is going to come out soon. The manuscripts are coming in fast and I sincerely hope that by the time these lines are printed we will be a t the galley proof stage of Volume 5B. Equally favorable is my report on the electronics Volume 2. A good part of the manuscripts have already been processed and the few missing ones should be in within the next few months so that concurrently with Volume 5B, Volume 2 also may be ready for the printer. The atomic and electron physics volume will have to be split, also, into Volumes 4A and B. Some of the manuscripts of 4A are on hand but it will take probably several months before we can start typesetting this volume. It