[...]... which two photons are emitted by excited states of an atom These photons may move off in opposite directions with the same polarization in the following meaning of the word same: If the photon moving to the East, say, is observed to have right-hand circular polarization, then the photon moving to the West is certain to be found to have right-hand circular polarization But if the photon moving to the East... physics This book introduces the most important aspects of quantum mechanics in the simplest way possible, but challenging aspects which are essential for a meaningful understanding have not been evaded It is an introduction to quantum mechanics which motivates the fundamental postulates of quantum mechanics by considering the weird behaviour of quantum particles reviews relevant concepts in classical... magnitude of the photon momentum decreases from pi to pf and the photon wavelength increases 1.1 3 Photons h ˆ 2X43  10À12 m, me c a fundamental length called the Compton wavelength of the electron The concept of a photon provides a natural explanation of the Compton effect and of other particle-like electromagnetic phenomena such as the photoelectric effect However, it is not clear how the photon can account... interpretation of quantum mechanics, a precise position or a precise momentum of an electron can be brought into existence by a measurement, but no attempt is made to explain how this occurs That properties are brought into existence by measurement is not restricted to the measurement of the position or momentum of a single particle It applies to other observable properties of a quantum particle and also to systems... xiv Editors' preface to the Manchester Physics Series Finally we would like to thank our publishers, John Wiley & Sons, Ltd, for their enthusiastic and continued commitment to the Manchester Physics Series D J Sandiford F Mandl A C Phillips February 1997 Author's preface There are many good advanced books on quantum mechanics but there is a distinct lack of books which attempt to give a serious introduction. .. collided with another atom Thus, this classical picture cannot explain why atoms are stable, why atoms of the same chemical element are always identical or why atoms have a surprisingly small variation in size In fact, atoms can only be understood by focussing on the wave-like properties of atomic electrons To some extent atoms behave like musical instruments When a violin string vibrates with definite... Compton showed that the wavelength of an X-ray increases when it is scattered by an atomic electron This effect, which is now called the Compton effect, can be understood by assuming that the scattering process is a photon± electron collision in which energy and momentum are conserved As illustrated in Fig 1.1, the incident photon transfers momentum to a stationary electron so that the scattered photon... b l e m s 10 213 215 219 222 224 ATOMS 11.1 11.2 11.3 Atomic Quantum States The central field approximation Corrections to the central field approximation The Periodic Table What If ? P r o b l e m s 11 229 230 234 238 241 246 Hints to selected problems 249 Further reading 262 Index 263 Physical constants and conversion factors Inside Back Cover Foreword Sadly, Tony Phillips, a good friend and colleague... alternatives is brought into existence by a subsequent measurement Amazingly, when this measurement is performed on one of the photons, say the photon moving East, there are two outcomes: The observed photon moving to the East has a specific polarization and the unobserved photon moving West immediately has the same polarization This system of entangled photons is equivalent to having two ambidextrous... of electron waves in an atom is that they are entangled so that it is not possible to tell which electron is which As a result, the possible electron wave patterns are limited to those that are compatible with a principle called the Pauli exclusion principle These patterns, for an atom with an atomic number Z, uniquely determine the chemical properties of all atoms with this atomic number All these ideas . Edition Computing for Scientists: R. J. Barlow and A. R. Barnett Nuclear Physics: J. S. Lilley Introduction to Quantum Mechanics: A. C. Phillips INTRODUCTION TO QUANTUM MECHANICS A. C. Phillips Department. Worcester Road, Rexdale, Ontario M9W 1L1, Canada Library of Congress Cataloging-in-Publication Data British Library Cataloguing in Publication Data A catalogue record for this book is available from. widely shared elsewhere, that many textbooks contain much more material than can be accommodated in a typical undergraduate course; and that this material is only rarely so arranged as to allow