In order to keep the book as current as possible, new developments in the direct observation of individual atoms in electromagnetic traps (Paul traps) and of atoms in molecules on solid surfaces using the scanning tunnel microscope have been added to this edition.

1. Introduction.- 2. The Mass and Size of the Atom.- 3. Isotopes.- 4. The Nucleus of the Atom.- 5. The Photon.- 6. The Electron.- 7. Some Basic Properties of Matter Waves.- 8. Bohr’s Model of the Hydrogen Atom.- 9. The Mathematical Framework of Quantum Theory.- 10. Quantum Mechanics of the Hydrogen Atom.- 11. Lifting of the Orbital Degeneracy in the Spectra of Alkali Atoms.- 12. Orbital and Spin Magnetism. Fine Structure.- 13. Atoms in a Magnetic Field: Experiments and Their Semiclassical Description.- 14. Atoms in a Magnetic Field: Quantum Mechanical Treatment.- 15. Atoms in an Electric Field.- 16. General Laws of Optical Transitions.- 17. Many-Electron Atoms.- 18. X-Ray Spectra, Internal Shells.- 19. Structure of the Periodic System. Ground States of the Elements.- 20. Nuclear Spin, Hyperfine Structure.- 21. The Laser.- 22. Modern Methods of Optical Spectroscopy.- 23. Fundamentals of the Quantum Theory of Chemical Bonding.- A. The Dirac Delta Function and the Normalisation of the Wavefunction of a Free Particle in Unbounded Space.- B. Some Properties of the Hamiltonian Operator, Its Eigenfunctions and Its Eigenvalues.- C. Derivation of Heisenberg’s Uncertainty Relation.- Solutions to the Problems.- Bibliography of Supplementary and Specialised Literature.- Fundamental Constants of Atomic Physics (Inside Front Cover).- Energy Conversion Table (Inside Back Cover).

The third edition had already been enlarged by the inclusion of new developments such as the direct observation of individual atoms in Paul traps, and of atoms in molecules on solid surfaces using the scanning tunneling microscope. Furthermore, new experiments in atomic interferometry and the possibility of laser cooling of atomic beams were added. The fourth English edition takes minor corrections and additions into account and remains a unique introduction to both experiments and theory of the physics of atoms and quanta. The student will find 160 problems and their solutions, making this book a real study text.