Chemical dynamics

CHEMICAL EDUCATION is changing rapidly, not only because of the explosive growth of knowledge but also because the new knowledge has stimulated reformulation of working principles in the science. Undergraduate curricula and individual courses are in constant flux. Nowhere is the change and challenge greater than in freshman chemistry. Teachers of freshmen must meet the intellectual needs of students who have had more sophisticated and stimulating high school courses than those given a decade ago. At the same time, the freshman teacher must be aware of the constant modification of the more advanced courses in chemistry and other fields that his students will study later. Continuous reformulation of courses sometimes results in the inclusion of valuable new material at the expense of other equally valuable material. We believe that this has happened in some of the sophisticated courses in freshman chemistry. Structural chemistry often receives far greater emphasis than chemical dynamics. In 1965, the Westheimer Report (Chemistry: Opportunities and Needs, National Academy of Sciences, 1965) identified the three major fields of chemistry as structure, dynamics, and synthesis. We firmly believe that a balanced course in general chemistry should reflect the outlook of this report. The study of modern chemical synthesis is too demanding to be covered in depth in an introductory course. However, chemical dynamics -- the systematic study of reactions and reactivity -- can and should be studied at the freshman level. The study of changing chemical systems is the most fascinating part of the field for many students, and its early introduction forms a solid foundation for later study. This small volume is our attempt to answer the need. The book is intended for students who have had introductory stoichiometry, energetics, and structure at the level of a modern freshman textbook (for example, Basic Principles of Chemistry, by H. B. Gray and G. P. Haight, Jr., W. A. Benjamin, Inc., New York, 1961). Chemical Dynamics is designed to accompany approximately 20-25 lectures to be given as the concluding section of a freshman chemistry course. We have chosen topics for their fundamental importance in dynamics and then tried to develop a presentation suitable for freshman classes. Discussion of each topic is limited, because chemistry majors will inevitably return to all the subject matter in more advanced courses. We hope that the following ideas have been introduced with a firm conceptual basis and in enough detail for the student to apply them to chemical reality. 1. Thermodynamics and kinetics are two useful measures of reactivity. 2. Characteristic patterns of reactivity are systematically related to molecular geometry and electronic structure. 3. Reaction mechanisms are fascinating in their own right and indispensable for identification of significant problems in reaction rate theory. 4. The concepts underlying experiments with elementary reaction processes (molecular beams) are simple, even though the engineering of the experiments is complicated. 5. Application of theories of elementary reaction rates to most reactions (slow reactions, condensed media, etc.) provides enough challenge to satisfy the most ambitious young scientist. The book includes exercises at the end of each chapter except the last. Their purpose is didactic, inasmuch as most have been written with the aim of strengthening a particular point emphasized in the chapter, or of introducing an important topic which was not developed in the text for reasons of space and which would normally be taken up in greater detail in later courses. The material in this volume has been adapted primarily from a portion of the lectures given by H.B.G. and G.S.H. to the Chemistry 2 students at the California Institute of Technology during the academic years 1966-1967 and 1967-1968. These lectures were taped, written up by J.B.D., and distributed to the students in the form of class notes. The final manuscript was written after class-testing of the notes. Our decision to revise the Chemistry 2 notes in the form of an introductory text was made after H.B.G. and G.S.H. participated in the San Clemente Chemical Dynamics Conference, held in December 1966 under the sponsorship of the Advisory Council of College Chemistry. At San Clemente we found we were not the only group concerned over the exclusion of significant reference to chemical reactions and reactivity relationships in freshman courses. In addition to their general encouragement, which provided the necessary additional impetus, these colleagues prepared a series of papers for publication in an issue of the Journal of Chemical Education. It is a pleasure to acknowledge here the direct contribution these papers made in shaping the final form of our volume; specifically, in preparing Chapter 6, we have drawn examples from the San Clemente papers of Professors R. Marcus, A. Kuppermann and E. F. Greene, and J. Halpern. The concluding chapter of this book was developed from the lectures given by Professors E. F. Greene (dynamics in simple systems), Richard Wolfgang (atomic carbon), John D. Roberts (nuclear magnetic resonance), and F. C. Anson (electrochemical dynamics) to the students of Chemistry 2 in May 1967. These colleagues have kindly given us permission to use their material. We are grateful to Professors Ralph G. Pearson and Paul Haake, who read the entire manuscript and offered valuable criticism. It is a special pleasure to acknowledge the enormous contribution our students in Chemistry 2 made to the project. Their enthusiastic, critical attitude helped us make many improvements in the manuscript. Thanks are also due to four very special members of the staff of W. A. Benjamin, Inc., for seeing this project through with infectious vigor. Finally, and not the least, we acknowledge the role Susan Brittenham and Eileen McKoy played in preparing the final manuscript. JOSEPH B. DENCE HARRY B. GRAY GEORGE S. HAMMOND Pasadena, California January 196

Inquiry into the interests of certain eighth-grade science pupils

Thesis (Ed.M.)--Boston University, 1946. This item was digitized by the Internet Archive

Renormalisation Group Flows in Lifshitz Holography

In this thesis we construct holographic duals of renormalisation group flows between field theories with conformal symmetries and the Lifshitz scaling symmetries. These take the form of spacetimes with a region asymptoting to AdS and another asymptoting to the Lifshitz metric of [1], with some domain wall smoothly interpolating between these regions. We first review the AdS/CFT correspondence in the context of Lorentz invariant boundary field theories, and then show how the holographic dictionary is modified by replacing the boundary field theory with one having the Lifshitz scaling symmetry. We then consider a pair of actions capable of supporting both Lifshitz and AdS spacetimes. The first of these is a massive vector field coupled to gravity and the second is the 6 dimensional Romans N = 4 massive gauged supergravity which supports 4D Lifshitz solutions. In each case we review the exact solutions that have been found previously, and then solve the linearised equations of motion around these solutions. These enable us to conjecture the existence of a variety of holographic RG flows. We then use numerical integration to confirm the existence of examples of each of these flows. In both theories we find Lifshitz to Lifshitz, AdS to Lifshitz, and Lifshitz to AdS flows. In the supergravity we also find AdS to AdS flows, and a Lifshitz to AdS flow which has an intermediate AdS region with a different dilaton value. In addition the supergravity has flows from a non-compact 6D AdS space to each of the 4D compactifications