 |
Electron and proton impact ionization of atoms and molecules
Theory of few-body Coulomb scattering
This is one of the major topics in the research activity of our laboratory. The long-range Coulomb potentials substantially modify the conventional scattering theory for short-range potentials. In particular, matrix elements of the scattering operator become divergent. We developed the correct procedure for their renormalization.
J-matrix approach
This method allows solving numerically the system of Faddeev-Merkuriev coupled equations, and it is also applied to the solution of the Schroedinger equations for three charged particles. This method is alternative to a well-known CCC method. Nevertheless, problems remain in the case of double ionization.
Single and double ionization of molecules
Presently it is one of the topical trends in the (e,2e) research activity, particularly in the case of biologically important targets such as a water molecule.
Electron momentum spectroscopy (EMS)
EMS is the (e,2e) method involving high incident energy and large momentum transfer. It measures momentum distribution of electrons in a target. We develop a theory of the single- and double-ionization EMS processes in atomic and molecular systems.
Light-matter interaction
Laser assisted electron momentum spectroscopy
Electron momentum spectroscopy (EMS) is a powerful tool for exploring momentum distribution of electrons in various systems, ranging from atoms and molecules to clusters and solids. We develop theory of EMS in the presence of laser radiation and investigate the potential of the method for studying the laser effects on electrons in atoms and molecules.
Multiple-photon double ionization of atoms
The aim of this project is to study the effect of electron-electron correlations in the initial and final wave packets on the ionization probability. Models of both initial and final wave functions, as well as of the interaction operator, are used. It was found that in some cases this influence is rather strong.
Ionization of hydrogen atom by a strong laser pulse
This archetypical case is used to probe different schemes for numerical calculations of the corresponding Schroedinger equation. In particular, the model of approaching the Coulomb potential by a sum of separable potentials gives very interesting and unexpected results. The aim of the investigation is to study the interplay between the atomic Coulomb potential and dipole time-dependent electric field and its effect on the ionization energy spectrum. Also this approach allows to study in more detail the dependence of the ionization spectrum on the field frequency and shape.
Capture processes
Charge transfer and transfer excitation reactions at small scattering angles
Recent precise measurements by the experimental Frankfurt team (R. Doerner) of the reaction p+He тЖТ H+He+ at high impact energies (Ep > 300 keV) allow to consider independently both ground state of the ion He+ and (integrally) its excited states. This makes it possible to study a contribution of different Born terms to the single differential cross section (SDCS). In particular, it was found that the plane-wave first- and second-Born terms give reasonable agreement with the experiment up to 1.5 mrad for charge transfer.
Transfer ionization reactions at small scattering angles
The experimental group from Frankfurt (R. Doerner et al.) made a serious progress in measuring single and double differential cross sections (SDCS and DDCS) of the reaction p+He -> H+He+++e at high impact energies (Ep > 300 keV). In particular, they presented DDCS depending on (kx,kz) and (kr,kz) distributions of electron momentum components. This makes it possible to study separately contributions of shake-off and two-step reaction mechanisms. These papers are under preparation.
Impact phenomena in condensed matter physics
Plasmon-assisted secondary electron emission from metallic surfaces
We develop a theoretical treatment for the ejection of a secondary electron from a clean metallic surface induced by the impact of a fast primary electron. Different models for dielectric response of the surface are examined, and the footprints of the surface- and the bulk-plasmon modes are determined and analyzed. The formulated theoretical approach is compared with the available experimental data on the electron-pair emission.
Searches for neutrino magnetic moments
Ionization of atoms by neutrino impact
Current direct experimental searches for a magnetic moment of the electron (anti)neutrinos from reactors have lowered the upper limit on its value down to 2.9E-11 in Bohr magnetons. These ultra-low-background experiments use semiconductor detectors exposed to the neutrino flux from a reactor and search for scattering events by measuring the energy T deposited by the neutrino scattering in the detector. Our theoretical analysis shows that the so-called stepping approximation to the neutrino-impact ionization is well applicable for the lowest bound Coulomb states, and it becomes exact in the semiclassical limit.
|
|
|
