University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Masters Theses Graduate School 8-2006 Structural and dynamical studies of superacids and superacidic solutions using neutron and high energy X-ray scattering Jamie John Molaison University of Tennessee - Knoxville Follow this and additional works at: https://trace.tennessee.edu/utk_gradthes Part of the Chemistry Commons Recommended Citation Molaison, Jamie John, "Structural and dynamical studies of superacids and superacidic solutions using neutron and high energy X-ray scattering. " Master's Thesis, University of Tennessee, 2006. https://trace.tennessee.edu/utk_gradthes/1741 This Thesis is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Masters Theses by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a thesis written by Jamie John Molaison entitled "Structural and dynamical studies of superacids and superacidic solutions using neutron and high energy X-ray scattering." I have examined the final electronic copy of this thesis for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Master of Science, with a major in Chemistry. John F. Turner, Major Professor We have read this thesis and recommend its acceptance: Richard M. Pagni, Jamie L. Adcock Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) To the Graduate Council: I am submitting herewith a thesis written by Jamie John Molaison entitled “Structural and dynamical studies of superacids and superacidic solutions using neutron and high energy X-ray scattering.” I have examined the final electronic copy of this thesis for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Master of Science, with a major in Chemistry. John F. C. Turner J Major Professor We have read this thesis and recommend its acceptance: Richard M. Pagni f Jamie L. Adcock f Accepted for the Council: Anne Mayhew f Vice Chancellor and Dean of Graduate Studies (Original signatures are on file with official student records) STRUCTURAL AND DYNAMICAL STUDIES OF SUPERACIDS AND SUPERACIDIC SOLUTIONS USING NEUTRON AND HIGH ENERGY X-RAY SCATTERING A Thesis Presented for the Master of Science Degree The University of Tennessee, Knoxville Jamie John Molaison August 2006 DEDICATION This work is dedicated to my parents, John and Chris Molaison, whose undying support proved invaluable to my success. I also dedicate this to my fiancée, Lauren, who never allowed me to quit in the face of adversity. ii ACKNOWLEDGEMENTS I would like to thank the members of the Turner Group for their support and camaraderie. I also wish to thank Joan Siewenie for all of her help before, during, and after running my scattering experiments and Dr. Chris Benmore for figuring out what was wrong with the data. Special thanks to my committee members, Dr. Jamie Adcock and Dr. Richard Pagni, for their patience and support during the thesis and defense processes. I’d like to thank Dr. Sylvia McLain for her valuable tutelage. Lastly, I thank my advisor, Dr. John Turner, for his help with and advice on matters of the lab and of life. iii ABSTRACT The diffusive motions of the Brønsted superacid, hydrogen fluoride, have been studied using quasielastic neutron scattering. Neutron and high energy X-ray diffraction measurements on the Lewis superacid, antimony pentafluoride, are presented along with the results of three applied data models. Finally, structural information was obtained for a 9:1 FSO3H:NH3 solution using neutron diffraction with isotopic substitution and nuclear magnetic resonance. iv 1 INTRODUCTION TO NEUTRON AND X-RAY SCATTERING AND AN OVERVIEW OF SUPERACIDS ......................................................................1 1.1 Properties of the neutron ........................................................................1 1.2 Neutron production .................................................................................2 1.3 Scattering theory......................................................................................5 1.3.1 Diffraction................................................................................................... 7 1.3.2 Neutron scattering measurements............................................................. 11 1.3.3 High energy X-ray measurements ............................................................ 13 1.3.4 Neutron diffraction from liquids............................................................... 14 1.3.5 Neutron diffraction data analysis.............................................................. 16 1.3.6 Quasielastic neutron scattering ................................................................. 17 1.4 Introduction to the chemistry and properties of superacids .............20 1.4.1 A brief history of superacids..................................................................... 20 1.4.2 Types of superacids................................................................................... 22 2 DYNAMICAL STUDIES OF LIQUID ANHYDROUS HYDROGEN FLUORIDE ..24 2.1 Introduction............................................................................................24 2.2 Experimental..........................................................................................27 2.2.1 Sample preparation................................................................................... 27 2.2.2 The QENS spectrometer ........................................................................... 29 2.2.3 Time of flight measurements .................................................................... 30 v 2.2.4 Resolution and focusing............................................................................ 32 2.2.5 Diffusion models....................................................................................... 34 2.2.6 Corrections to the data .............................................................................. 37 2.3 Results.....................................................................................................40 2.3.1 Data and fits .............................................................................................. 40 2.3.2 QENS and previous studies ...................................................................... 45 2.4 Discussion ...............................................................................................49 2.4.1 Trends in the data...................................................................................... 49 2.4.2 QENS vs. NMR ........................................................................................ 50 2.4.3 HF vs. H2O................................................................................................ 52 2.5 Conclusions.............................................................................................54 3 THE STRUCTURE OF LIQUID ANTIMONY PENTAFLUORIDE.....................55 3.1 Introduction............................................................................................55 3.1.1 Previous studies........................................................................................ 56 3.1.2 Structure models....................................................................................... 58 3.2 Experimental..........................................................................................61 3.2.1 Sample handling and preparation.............................................................. 61 3.2.2 Neutron diffraction....................................................................................62 3.2.3 High energy X-ray diffraction .................................................................. 62 3.2.4 EPSR......................................................................................................... 63 vi 3.3 Results.....................................................................................................67 3.3.1 Neutron Diffraction................................................................................... 67 3.3.2 High energy X-Ray diffraction ................................................................. 68 3.4 Discussion ...............................................................................................70 3.4.1 Pair correlation functions.......................................................................... 70 3.4.2 Coordination number analysis .................................................................. 72 3.4.3 EPSR fits................................................................................................... 73 3.5 Conclusions.............................................................................................78 4 STRUCTURAL STUDIES OF AMMONIA IN FLUOROSULFURIC ACID..........81 4.1 Introduction............................................................................................81 4.1.1 Structural studies of solutes ...................................................................... 81 4.1.2 The solid state structure of ammonium fluorosulfate ............................... 82 4.1.3 Proton transfer between ammonia and fluorosulfuric acid....................... 85 4.2 Experimental..........................................................................................89