Z. Roller-Lutz

Angle-differential measurement of H (2p) electron capture in H+ collision with Na (3s) and laser-excited Na (3p) atoms

Abstract We present the first measurement of angle-differential Lyman-α production in H + collision with Na in the ground 3s and excited 3p states at scattering angles 0.05°–0.3°; the collision energy is 1 keV. The results are in fair agreement with predictions of recent calculations.

Angle-differential H(2p) alignment in 1 keV H+-Na charge exchange collisions

In a Lyman alpha photon-scattered particle coincidence experiment, the angle-differential H(2p) alignment has been determined for 1 keV H+ impact on Na. At small scattering angles, large preferential population of the H(2p, m=0) substate is found. The results are in good agreement with coupled-channel calculations by Shingal.

Electron capture and ionization for ion - Rydberg atom collisions in a magnetic field

Within the classical trajectory Monte Carlo (CTMC) model, we calculate electron transfer and ionization cross sections for singly charged ions colliding with Rydberg atoms in the presence of a laboratory-strength magnetic field of 4 tesla. A new method for generating a stationary microcanonical ensemble for a quasi-integrable initial-state Hamiltonian is presented. The calculated cross sections show signatures of electron capture and ionization mechanisms for the field-free case, e.g. multiple swaps and saddle-point electrons; their structure as well as their magnitude, however, are strongly modified by the presence of the magnetic field.

Classical trajectory Monte Carlo calculations of electron capture and ionization in collisions of multiply charged ions with elliptical Rydberg atoms

We have performed classical trajectory Monte Carlo (CTMC) studies of electron capture and ionization in multiply charged (Q=8) ion-Rydberg atom collisions at intermediate impact velocities. Impact parallel to the minor and to the major axis, respectively, of the initial Kepler electron ellipse has been investigated. The important role of the initial electron momentum distribution found for singly charged ion impact is strongly disminished for higher projectile charge, while the initial spatial distribution remains important for all values of Q studied.

Electron capture in multiply charged ion-Rydberg atom collisions in an external magnetic field

Using the classical trajectory Monte Carlo method, we calculated charge transfer cross sections for 1.27-183 eV amu-1 singly and multiply charged ions (Q = 1,2,4 and 8) colliding with Rydberg atoms in a magnetic field of up to 4 T. The results show a significant influence of the magnetic field, and the velocity-dependent cross sections become increasingly featureless for increasing projectile charge.

Electron emission and trapping in ion - Rydberg atom collisions in a magnetic field

With an extended version of the classical trajectory Monte Carlo method to take into account the quasi-integrable initial state, we calculate the ionization cross section for singly charged ions colliding with Rydberg atoms in the presence of a magnetic field of 4 Tesla. Strong evidence for long-lived quasi-bound states, created and located around three centres (target nucleus, projectile nucleus and potential saddle between the two) is found which are caused by the trapping and multiple scattering of emitted electrons in the external fields.

The role of an initial Na(3p) state alignment in 1 keV H++Na(3p)→H(2p)+Na+ collisions

Charge exchange in 1 keV H++Na→H(2p)+Na+ is studied in a Lyman-α scattered particle coincidence experiment. An initial Na(3p) state is prepared by laser-optical pumping; its alignment is controlled by the laser light polarization. The results are compared to a 34 coupled-channels calculation (R. Shingal), and discussed on the basis of an asymptotic model of the charge exchange process.