Excitation of heavy hydrogen-like ions by light atoms in relativistic collisions with large momentum transfers

We present a theory for excitation of heavy hydrogen-like projectile-ions by light target-atoms in collisions where the momentum transfers to the atom are very large on the atomic scale. It is shown that in this process the electrons and the nucleus of the atom behave as (quasi-) free particles with respect to each other and that their motion is governed by the field of the nucleus of the ion. The effect of this field on the atomic particles can be crucial for the contribution to the excitation of the ion caused by the electrons of the atom. Due to comparatively very large nuclear mass, however, this field can be neglected in the calculation of the contribution to the excitation due to the nucleus of the atom.Comment: 15 pages, 2 figure

Resonant two-photon single ionization of two atoms

Resonant two-photon ionization in a system consisting of two spatially well-separated atoms is studied. Due to two-center electron-electron correlations, the ionization may also proceed through photo-excitation of both atoms with subsequent interatomic Coulombic decay. We show that this channel may dominate the photoionization process and qualitatively change its dependence on the field intensity and the spectra of emitted electrons.Comment: 4 pages, 4 figure

Excitation of highly charged hydrogen-like ions by the impact of equivelocity electrons and protons: a comparative study

We consider excitation of highly charged hydrogen-like ions by the impact of equivelocity electrons and protons. The kinetic energy of the protons is more than three orders of magnitude larger than that of the equivelocity electrons. It is shown, however, that despite this fact, the electrons can be much more effective in inducing excitation at collision velocities (slightly) above the threshold for electron impact excitation. The basic reason for this is the strong distortion of the motion of the electron by the attractive field of the nucleus of the highly charged ion.Comment: 5 pages, 5 figure

Relativistic electron-ion recombination in the presence of an intense laser field

Radiative recombination of a relativistic electron with a highly charged ion in the presence of an intense laser field is considered. Various relativistic effects, caused by the high energy of the incoming electron and its strong coupling to the intense laser field, are found to clearly manifest themselves in the spectra of the emitted $\gamma$-photons.Comment: 4 papes, 2 figure

Young-type interference in projectile-electron loss in energetic ion-molecule collisions

Under certain conditions an electron bound in a fast projectile-ion, colliding with a molecule, interacts mainly with the nuclei and inner shell electrons of atoms forming the molecule. Due to their compact localization in space and distinct separation from each other these molecular centers play in such collisions a role similar to that of optical slits in light scattering leading to pronounced interference in the spectra of the electron emitted from the projectile.Comment: 4 pages, 3 figure

Two-center resonant photo ionization

Photoionization of an atom $A$, in the presence of a neighboring atom $B$, can proceed via resonant excitation of $B$ with subsequent energy transfer to $A$ through two-center electron-electron correlation. We demonstrate that this two-center mechanism can strongly outperform direct photoionization at nanometer internuclear distances and possesses characteristic features in its time development and the spectrum of emitted electrons.Comment: 4 pages, 3 figure

Relativistic transfer ionization and the Breit interaction

We consider correlated transfer ionization in relativistic collisions between a highly charged ion and a light atom. In this process two quasi-free electrons of the atom interact with each other during the short collision time that results in capture of one of them by the ion and emission of the other. We show that this process is strongly influenced by the generalized Breit interaction already at modest relativistic impact energies.Comment: 5 pages, 4 figure

Collectively enhanced resonant photoionization in a multi-atom ensemble

Photoionization of an atom via interatomic correlations to N neighboring atoms may be strongly enhanced due to constructive interference of quantum pathways. The ionization proceeds via resonant photoexcitation of a neighbor atom and subsequent interatomic Coulombic decay. The enhancement can scale with N^2, leading to "super-enhanced photoionization".Comment: 4 pages, 2 figure