Coherent laser spectroscopy of ¯pHe+

The facilities of the coherent laser pulse spectroscopy of the ¯pHe⁺ transitions are considered taking the magnetic structure of the energy levels into account. The possibility for the observation of the dynamics of intramolecular motions is also analyzed.     

Adiabatic representation for a hydrogen atom photoionization in a uniform magnetic field

A new effective method of calculating wave functions of discrete and continuous spectra of a hydrogen atom in a strong magnetic field is developed on the basis of the adiabatic approach to parametric eigenvalue problems in spherical coordinates. The two-dimensional spectral problem for the Schrödinger equation at a fixed magnetic quantum number and parity is reduced to a spectral parametric problem for a one-dimensional angular equation and a finite set of ordinary second-order radial differential equations. The results are in good agreement with the photoionization calculations by other authors and have a true threshold behavior.     

Quantum Transparency of Barriers and Reflection from Wells for Clusters of Identical Particles

A method for solving the problem of quantum transmission through potential barriers or potential wells for a compound system consisting of several identical particles coupled via pair oscillator-type potentials in the oscillator representation of the symmetrized coordinates is considered. The efficiency of the proposed approach, algorithms and programs is demonstrated by the examples of calculation of complex energy values and analysis of metastable states of compound systems of two, three, and four identical particles on a straight line, which lead to the effect of quantum transparency of the potential barriers or quantum reflection from the wells.     

Properties of the phase space and bifurcations in the complex Lorenz model

The geometrical structure of the phase space and bifurcations in the complex Lorenz model are investigated. It is shown that the hierarchy of bifurcations in a single-mode laser with detuning of the resonator frequency from the frequency of a spectral line is similar to the hierarchy of bifurcations of the logistic map. Zh. Tekh. Fiz. 68, 1–9 (August 1998)     

Vibration-rotational super-high resolution spectrum of OsO4 and its theoretical interpretation

The vibration-rotational spectrum of the OsO₄ molecule is studied using a non-linear, laser, super-high resolution technique for 18 Doppler-broadened lines of the CO₂-laser. An attempt at theoretical interpretation of the data is also included.     

Adiabatic Representation for Atomic Dimers and Trimers in Collinear Configuration

Physics of Atomic Nuclei - We considered collinear models for a trimer of identical atoms with molecular pair interactions and for an atomic dimer scattered by an atom or tunneling through...     

Theory of four-photon scattering in conditions of intense resonant excitation

Journal of Applied Spectroscopy -     

Metastable states of a composite system tunneling through repulsive barriers

We consider a method for solving the problem of quantum tunneling through repulsive potential barriers for a composite system consisting of several identical particles coupled via pair oscillator-type potentials in the oscillator symmetrized-coordinate representation. We confirm the efficiency of the proposed approach by calculating complex energy values and analyzing metastable states of composite systems of three, four, and five identical particles on a line, which leads to the effect of quantum transparency of the repulsive barriers.     

Resonant tunneling of a few-body cluster through repulsive barriers

A model for quantum tunnelling of a cluster comprised of A identical particles, interacting via oscillator-type potential, through short-range repulsive barrier potentials is introduced for the first time in symmetrized-coordinate representation and numerically studied in the s-wave approximation. A constructive method for symmetrizing or antisymmetrizing the (A ? 1)-dimensional harmonic oscillator basis functions in the new symmetrized coordinates with respect to permutations of coordinates of A identical particles is described. The effect of quantum transparency, manifesting itself in nonmonotonic resonance-type dependence of the transmission coefficient upon the energy of the particles, their number A = 2, 3, 4 and the type of their symmetry, is analyzed. It is shown that the total transmission coefficient demonstrates the resonance behavior due to the existence of barrier quasi-stationary states, embedded in the continuum.     

Modern methods for calculating photoionization and electron-impact ionization of two-electron atoms and molecules

A number of recently developed methods for calculating multifold differential cross sections for photoionization and electron impact ionization of atoms and molecules with two active electrons are reviewed. The methods are based on unique approaches to the calculation of three-body Coulomb wave functions. The exterior scaling method and the driven Schrödinger equation formalism are considered. The effectiveness of the time-dependent approaches to the scattering problem, such as the paraxial approximation and the time-dependent scaling, is demonstrated. A novel numerical method is formulated, which has been developed by the authors to solve the six-dimensional Schrödinger equation for an atom with two active electrons on the basis of the Chang-Fano transformation and the discrete variable representation. The threshold behavior manifested by the angular distributions of the two-electron photoionization of a negative hydrogen ion and a helium atom and the multifold differential cross sections for the electronimpact ionization of hydrogen and nitrogen molecules are analyzed on the basis of numerical simulations. The Wannier law for the angular distribution of double ionization is demonstrated to be incorrect even at very low energies.