Dynamics of Single-Pulse Echo Signals under the Conditions of Zeeman Switching

The signals of a single-pulse echo (SE) generated on nonresonant excitation of an inhomogeneously broadened two-level system by a radio-frequency pulse (RFP), against the background of which a magnetic video pulse (MVP) of certain length has been switched on, have been described analytically. It is established that under the conditions of such excitation several SE signals are formed whose generation moments are determined by the duration and amplitudes of the RFP and MVP. The amplitudes of some of these signals depend on the Rabi frequency according to a quadratic law, and the amplitudes of others depend on this frequency according to a biquadratic law. It has been established that the mechanism underlying the appearance of these signals is associated with zero beats arising as a result of superposition of the magnetization fluctuations at variable frequencies and at a frequency of detuning from resonance. It is shown that in the limiting case, where the RFP duration considerably exceeds the duration of the MVP or is comparable with it, the number of SE signals decreases to two. Theoretical results on the formation of SE and the dependence of the amplitude of these signals on the MVP amplitude agree with the experimental data on NMR pulsed signals in ferromagnetic materials.     

Mathematical Modeling of Magnetohydrodynamic Processes in an Aluminum Electrolyzer

We model the electrolysis of aluminum in specific electrolysis baths. A model of the physical process is proposed, allowing for the specific bath design, including the state of the bottom surface. The mathematical model utilizes the information capabilities of the Navier–Stokes equations written for the metal and the electrolyte media. The multidimensional system of equations enables us to consider the magnetohydrodynamic processes in two media and the interaction of the media. The problem is solved numerically. The calculations simulate the interface dynamics and the distribution of velocities and currents in the middle layer in both media. The numerical results are compared with physical experiments.     

A completely conservative difference scheme of gas dynamics in orthogonal curvilinear coordinates

A completely conservative difference scheme in Eulerian curvilinear orthogonal coordinates is proposed for calculating discontinuous gas-dynamic flows on sufficiently coarse grids. The stability of the linear approximation of the proposed scheme is analyzed. Courant's condition provides a stability condition for this scheme.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 58, pp. 9–15, 1986.     

Photochemical reduction of organic electron acceptors in aqueous solutions

Conclusions The formation of OH radicals in the photoreduction of aqueous solutions of anthraquinonesulfonic acid as the result of electron transfer from water (OH^–) to a triplet molecule has been demonstrated.Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2615–2617, November, 1969.     

The selective chlorination of organohydridesilanes

Conclusions A convenient method of preparing organochlorohydridesilanes by selective chlorination of organohydridesilanes with stannic chloride was proposed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2114–2117, September, 1967.     

Laser photolysis of dicarbocyanine dyes

Russian Chemical Bulletin -