Single ionization and electron capture in He²⁺+Na collisions

Abstract

Single-electron capture and ionization in He2++Na collisions at energies around the matching velocity (2–13 keV amu−1) have been studied both experimentally and theoretically. State-selective cross section for capture into the n = 2, 3, 4 and n ⩾ 5, and the ionization cross section as well as differential cross sections for capture into n = 3 and 4 were obtained by the MOTRIMS method and compared with CTMC calculations. Good agreement was found between experiment and CTMC, especially concerning capture into high n-shells (n = 4, n ⩾ 5) and the ionization cross sections. For capture into the subdominant n = 2 shell close coupling calculations show better agreement. The differential cross sections for capture into n = 3 and 4 show a different energy dependency.

State-selective electron transfer and ionization in collisions of highly charged ions with ground-state Na(3s) and laser-excited Na*(3p)

“…Our MOTRIMS apparatus has been described elsewhere [17]. In short, the 23 Na atoms providing the target are cooled and trapped in a magneto-optical trap (MOT) using a magnetic field with a gradient of 20 G/cm and three counterpropagating laser beams with a diameter of 20 mm each, which are red detuned to the 3s 2 S 1/2 , F = 2 → 3p 2 P 3/2 , F = 3 transition frequency by 20 MHz.…”

Coulomb over-the-barrier Monte Carlo simulation to probe ion-dimer collision dynamics

“…The relative cross sections associated to the different elementary processes (ionization, excitation and electron capture from the atomic target) depend strongly on the collision regime, given by the comparison of the projectile velocity (v p ) to the orbital velocity of active electrons (v e ) and by the collision asymmetry, i.e. the ratio between the projectile and target atomic numbers [5][6][7][8]. It is today well established that, as ionization and excitation of the target dominates in the high velocity regime, charge exchange (or electron capture) is by far the most probable process at low energy.…”

Oscillatory patterns in angular differential ion-atom charge exchange cross sections: The role of electron saddle swaps

“…Since the MOTRIMS device developed at KVI has been described elsewhere [10,14] only a brief outline will be given here. Sodium atoms are cooled and trapped in a magneto-optical trap (MOT) using a magnetic field of 20 Gauss/cm and three counterpropagating laser beams with a diameter of 20 mm each.…”

“…Such an advance also led to the development of new techniques, like the magnetooptical trap recoil-ion momentum spectroscopy (MOTRIMS) [7][8][9] in which a target that is laser cooled and magnetically trapped is used in the reaction microscope. By using this technique, during the last few years the KVI group succeeded in obtaining nstate selective charge exchange cross sections for ion collisions with Na(3s) and Na*(3p) [10]. These cross sections have been checked against classical trajectory Monte Carlo (CTMC) calculations and are shown to be in good agreement for the collision systems and impact energy ranges explored [11][12][13][14].…”