Table of contents

A high-intensity, pulsed, gasdynamically cooled supersonic molecular flow (beam) interacting with a solid surface produces a pressure shock with nonequilibrium conditions T_{2, tr} ≥ T_{2, rot} ≥ T_{2, vib} inverse to those in the incident beam, T_{1, tr} ≤ T_{1, rot} ≤ T_{1, vib}, (T_{i, tr}, T_{i, rot}, and T_{i, vib} are the translational, rotational, and vibrational molecular temperatures, respectively). This provides the possibility for studying the isotopically selective IR multiphoton molecular dissociation under new nonequilibrium conditions and for considerably increasing the efficiency of the process. Due to pressure shock formation near the surface, duration-controlled molecular beam pulses, intense kinetic-energy-variable secondary molecular beams, and intense beams of accelerated cold radicals can be obtained. In the present paper, research aimed at producing duration-controlled molecular beams, high-intensity secondary pulsed molecular beams, high-energy secondary pulsed molecular beams with IR-laser-controlled kinetic energy, and low-energy molecular beams is reviewed.

Theoretical and experimental research into the dynamic and correlation properties of smectic liquid-crystal films is reviewed. Both freely suspended films and films fastened to a solid substrate are considered. For smectic-A films, the intensity of X-ray scattering and the temporal correlation function of scattering intensities are analyzed. For smectics with the director tilted with respect to the layers, the intensity of scattering light is discussed. To illustrate theoretical results, available experimental data are used.

Current views on Dirac's creative heritage and on his role in the formation and development of quantum physics and in shaping the physical picture of the world are discussed. Dirac's fundamental ideas in later life (1948 – 1984) and their current development are given considerable attention.

The historical development of the concept of the topological phase in classical mechanics from the mid-19th century to the present is discussed. There are three stages to be recognized in this period. The first, the mid-19th century stage, is concerned with studying the kinematics of rigid body rotation and includes such milestone developments as the Euler theorem on finite rotation of rigids, Gauss formula for the sum excess of the angles of a spherical polygon, Rodrigues's proof of the noncommutativity property of two finite rotations, and, finally, Hamilton's Lectures on Quaternions where the solid angle theorem is formulated and proved. The experimental discovery of the nonholonomic error of gyroscopes and its exhaustive explanation by A Yu Ishlinskii represent the second stage. The third stage, which started in the 1980s, has witnessed the rediscovery of the nonholonomic effect in the framework of Hamiltonian formalism and is dominated by the study of how the topological phase — or an additional angle — forms in a mechanical system being treated in action–angle variables.