Application of the quantum theory of scattering to the calculation of the angular distribution of H+, D+, and T+ in collisions with He

The differential angular cross section for single ionization of He in collisions with H⁺, D⁺, and T⁺ has been calculated within the framework of the three-body approximation. The results of the calculations of the angular distribution of H⁺, D⁺, and T⁺ are compared with the available experimental and calculational data. Translated from a manuscrip submitted December 10, 1996.     

The Few-Body Approximation in Nuclear,Atomic, and Molecular Physics

The quantum theory of few-body scattering based on Faddeev-Yakubovsky integral and differential equa¬tions is applied to calculations of various processes (elastic, inelastic, atom exchange, and dissociative) in nuclear, atomic, and molecular physics. Analytical solutions of these equations are presented for various limiting cases. The methods used for solving the integral and differential systems of equations are discussed.     

Resonances in electron scattering by molecules

The main features of resonance scattering of electrons by molecules are described and resonances are determined on the basis of the theory of collisions in a two-body system, as well as resonances emerging as a result of collisions in a few-body system. Regularities in the emergence of such resonances and their characteristics are analyzed. The results of calculations of these resonant processes occurring during collisions of electrons with diatomic molecules, made on the basis of the quantum theory of scattering in a few-body system, are presented. The results of calculating the cross sections of resonant processes of electron collisions with molecules are compared with the available experimental data and with the results of calculations based on other approximations.     

Realistic modeling of ion cloud motion in a Fourier transform ion cyclotron resonance cell by use of a particle-in-cell approach

Using a 'Particle-In-Cell' approach taken from plasma physics we have developed a new three-dimensional (3D) parallel computer code that today yields the highest possible accuracy of ion trajectory calculations in electromagnetic fields. This approach incorporates coulombic ion-ion and ion-image charge interactions into the calculation. The accuracy is achieved through the implementation of an improved algorithm (the so-called Boris algorithm) that mathematically eliminates cyclotron motion in a magnetic field from digital equations for ion motion dynamics. It facilitates the calculation of the cyclotron motion without numerical errors. At every time-step in the simulation the electric potential inside the cell is calculated by direct solution of Poisson's equation. Calculations are performed on a computational grid with up to 128 x 128 x 128 nodes using a fast Fourier transform algorithm. The ion populations in these simulations ranged from 1000 up to 1,000,000 ions. A maximum of 3,000,000 time-steps were employed in the ion trajectory calculations. This corresponds to an experimental detection time-scale of seconds. In addition to the ion trajectories integral time-domain signals and mass spectra were calculated. The phenomena observed include phase locking of particular m/z ions (high-resolution regime) inside larger ion clouds. A focus was placed on behavior of a cloud of ions of a single m/z value to understand the nature of Fourier transform ion cyclotron resonance (FTICR) resolution and mass accuracy in selected ion mode detection. The behavior of two and three ion clouds of different but close m/z was investigated as well. Peak coalescence effects were observed in both cases. Very complicated ion cloud dynamics in the case of three ion clouds was demonstrated. It was found that magnetic field does not influence phase locking for a cloud of ions of a single m/z. The ion cloud evolution time-scale is inversely proportional to magnetic field. The number of ions needed for peak coalescence depends quadratically on the magnetic field.     

Trends in electronic-transition chemical lasers

A new class of chemical lasers based on electronic transitions of atoms, radicals, or molecules excited via oxidation chain reactions in the presence of catalysts is proposed and discussed. The possibility is considered of using these processes to realize four lasing schemes: directly via transitions of excited intermediate products, in an exchange chemical laser, using narrowband chemical lamps, and in chemical-excimer lasers. A number of specific active mixtures are proposed. The gain of a realizable chemical Na-BaOlaser is calculated. The possibility of using chemical reactions with participation of cluster molecules are analyzed. The use of atoms as acceptor (emitting) particles is discussed. Two methods of obtaining increased atom densities are proposed. Certain possibilities of obtaining cw lasing on self-limiting atom transitions are considered.This preprint is the text of a paper delivered at the 3rd International Conference on Trends in Quantum Electronics, Bucharest, 29 August-3 September 1988.Translated from Preprint No. 36 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1989.     

Application of Quantum Scattering Theory in Calculation of the Simplest Chemical Reactions (Dissociative Attachment,Dissociation, and Recombination)

Technical Physics - Several parameters (cross section, reaction rate, etc.) of various processes in laser, atomic, and chemical physics are calculated using quantum scattering theory for a system...