Table of contents

CONTENTS 1. Introduction 609 2. Geometrical Optics of a Nonlinear Medium (Equations, Focal Points, Nonlinear Aberrations, Nonstationary Processes) 617 3. Wave Optics of a Nonlinear Medium (Diffraction Corrections to the Self-focusing Length, Formation of Proper Optical Waveguide, Nonstationary Processes) 624 4. Nonlinear Optical Effects in the Field of Self-focusing Beams (Stimulated Scattering in Liquids, Experimental Data, Self-focusing and Parametric Amplification) 629 5. Conclusion (Unsolved Problems, Diffraction in Nonlinear Interactions) 632 Cited Literature 634

CONTENTS I. Introduction 637 II. Theory of the Stark Effect 638 1. The Stark Effect in a Constant Electric Field 638 2. The Stark Effect in Alternating Electric Fields 640 III. The Study of the Stark Effect in a Constant Electric Field 643 1. Observation of the Shifts of Centers of Gravity of Absorption Lines in Atomic Beams 643 2. Study of the Stark Effect by Observation of Electric Double Refraction 644 3. Study of the Stark Effect by the Method of Comparison with Hyperfine Splitting 646 4. Observation of the Stark Effect by Radiospectroscopic Methods 646 5. Study of the Stark Effect by the Method of Double Radiooptical Resonance 647 6. Observation of the Stark Effect by Level-crossing and Beat Methods 649 IV. The Study of the Stark Effect in Fields of Optical Frequency 651 1. Observation of Shifts and Splittings of Levels of the Ground State of Hg¹⁹⁹ by Resonance Light 651 2. Observation of Shifts and Splittings of Levels of Potassium Atoms in the Radiation Field of a Ruby Laser 653 V. Conclusion 654 Literature Cited 656

CONTENTS Introduction 658 I. Experimental Data on the Isotope Shift 659 1. The Isotope Shift in the Spectra of Strontium, Zirconium, Molybdenum, and other Intermediate Elements 659 2. The Isotope Shift in the Spectra of Isotopes of Heavy Elements of Neutron Numbers 82-126. 662 3. The Isotope Shift in the Spectra of the Actinide Elements 666 II. Theory of the Isotope Shift in the Spectra of the Heavy Elements 668 III. Comparison of the Theory of the Isotope Shift with Experiment 670 Bibliography 671

CONTENTS I. Physics in Russia Before the Revolution and Start of Organization of Soviet Physics 678 II. Review of Work of Soviet Physicists 686 General Problems of Theoretical Physics 686 Elementary Particle Physics 688 Physics of the Atomic Nucleus 693 Plasma Physics 697 Optics. Physics of Atoms and Molecules 697 Quantum Electronics 705 Radiophysics and Theory of Oscillations 706 Low Temperatures 709 Physics of Dielectrics 712 Physics of Semiconductors 713 Mechanical Properties of Solids 715 Magnetism 716 Acoustics 718 III. Organizational Problems. Scientific literature 718