Claude Cohen-Tannoudji is a researcher at the Kastler-Brossel laboratory of the Ecole Normale Supérieure in Paris where he also studied and received his PhD in 1962. In 1973 he became Professor of atomic and molecular physics at the Collège des France. His main research interests were optical pumping, quantum optics and atom-photon interactions. In 1997, Claude Cohen-Tannoudji, together with Steven Chu and William D. Phillips, was awarded the Nobel Prize in Physics for his research on laser cooling and trapping of neutral atoms.Bernard Diu was Professor at the Denis Diderot University (Paris VII). He was engaged in research at the Laboratory of Theoretical Physics and High Energy where his focus was on strong interactions physics and statistical mechanics.Franck Laloë is a researcher at the Kastler-Brossel laboratory of the Ecole Normale Supérieure in Paris. His first assignment was with the University of Paris VI before he was appointed to the CNRS, the French National Research Center. His research was focused on optical pumping, statistical mechanics of quantum gases, musical acoustics and the foundations of quantum mechanics.

• AN ELEMENTARY APPROACH TO THE QUANTUM THEORY OF SCATTERING BY A POTENTIALIntroductionStationary Scattering States. Calculation of the Cross SectionScattering by a Central Potential. Method of Partial WavesComplementsELECTRON SPINIntroductionSpecial Properties of Angular Moment 1/2Non-Relativistic Description of a Spin 1/2 ParticleComplementsADDITION OF ANGULAR MOMENTAIntroductionAddition of Two Spin 1/2's. Elementary MethodAddition of Two Arbitrary Angular Momenta. General MethodsComplementsSTATIONARY PERTURBATION THEORYDescription of the MethodPerturbation of a Non-Degenerate LevelPerturbation of a Degenerate LevelComplementsAN APPLICATION OF PERTURBATION THEORY: THE FINE AND HYPERFINE STRUCTURE OF THE HYDROGEN ATOMIntroductionAdditional Terms in the HamiltonianThe Fine Structure of the N=2 LevelThe Hyperfine Structure of the N=1 LevelThe Zeeman Effect of the Hyperfine Structure of the 1s Ground StateComplementsAPPROXIMATION METHODS FOR TIME-DEPENDENT PROBLEMSStatement of the ProblemApproximate Solution of the Schrödinger EquationAn Important Special Case: Sinusoidal or Constant PerturbationComplementsSYSTEMS OF IDENTICAL PARTICLESStatement of the ProblemPermutation OperatorsThe Symmetrization PostulateDiscussionComplementsAPPENDICESFourier Series and the Fourier TransformThe Dirac "Function"The Lagrangian and Hamiltonian in Classical Mechanics

Claude Cohen-Tannoudji is a researcher at the Kastler-Brossel laboratory of the Ecole Normale Supérieure in Paris where he also studied and received his PhD in 1962. In 1973 he became Professor of atomic and molecular physics at the Collège des France. His main research interests were optical pumping, quantum optics and atom-photon interactions. In 1997, Claude Cohen-Tannoudji, together with Steven Chu and William D. Phillips, was awarded the Nobel Prize in Physics for his research on laser cooling and trapping of neutral atoms.Bernard Diu was Professor at the Denis Diderot University (Paris VII). He was engaged in research at the Laboratory of Theoretical Physics and High Energy where his focus was on strong interactions physics and statistical mechanics.Franck Laloë is a researcher at the Kastler-Brossel laboratory of the Ecole Normale Supérieure in Paris. His first assignment was with the University of Paris VI before he was appointed to the CNRS, the French National Research Center. His research was focused on optical pumping, statistical mechanics of quantum gases, musical acoustics and the foundations of quantum mechanics.

• AN ELEMENTARY APPROACH TO THE QUANTUM THEORY OF SCATTERING BY A POTENTIALIntroductionStationary Scattering States. Calculation of the Cross SectionScattering by a Central Potential. Method of Partial WavesComplementsELECTRON SPINIntroductionSpecial Properties of Angular Moment 1/2Non-Relativistic Description of a Spin 1/2 ParticleComplementsADDITION OF ANGULAR MOMENTAIntroductionAddition of Two Spin 1/2's. Elementary MethodAddition of Two Arbitrary Angular Momenta. General MethodsComplementsSTATIONARY PERTURBATION THEORYDescription of the MethodPerturbation of a Non-Degenerate LevelPerturbation of a Degenerate LevelComplementsAN APPLICATION OF PERTURBATION THEORY: THE FINE AND HYPERFINE STRUCTURE OF THE HYDROGEN ATOMIntroductionAdditional Terms in the HamiltonianThe Fine Structure of the N=2 LevelThe Hyperfine Structure of the N=1 LevelThe Zeeman Effect of the Hyperfine Structure of the 1s Ground StateComplementsAPPROXIMATION METHODS FOR TIME-DEPENDENT PROBLEMSStatement of the ProblemApproximate Solution of the Schrödinger EquationAn Important Special Case: Sinusoidal or Constant PerturbationComplementsSYSTEMS OF IDENTICAL PARTICLESStatement of the ProblemPermutation OperatorsThe Symmetrization PostulateDiscussionComplementsAPPENDICESFourier Series and the Fourier TransformThe Dirac "Function"The Lagrangian and Hamiltonian in Classical Mechanics