Evidence of electron saddle swap oscillations in angular differential ion–atom charge exchange cross sections

Abstract

State selective charge exchange processes in 1–10 keV/amu Ne8+ +Na(3s) collisions were measured by means of the magneto-optical trap recoil-ion momentum spectroscopy technique and compared to classical trajectory Monte Carlo calculations. We find that for electron capture to n-levels ≥ 10, the transverse momentum distributions exhibit an oscillatory structure which is very sensitive to the impact energy. Our theoretical analysis suggests that this feature is a direct consequence of the number of swaps the electron undergoes across the potential energy saddle during the charge exchange process.

Role of electron saddle swaps in the photon spectra following Li3+charge-exchange collisions with H*(n= 2), Na(3Otranto1, Hoekstra2, Olson3 2014Phys. Rev. A

“…In a recent joint collaboration with the Groningen group, we have studied state-selective charge-exchange processes between He-like projectiles (in particular, N 5+ and Ne 8+ ) with Na(3s) and Na * (3p). Their angular differential studies evidenced an energy-dependent oscillatory structure which was well reproduced by classical trajectory Monte Carlo (CTMC) calculations and was ascribed to the possible different numbers of electron saddle crossings which take place during the capture process [7,8]. Early on, oscillations were observed on the visible line emission cross sections for C 6+ and O 8+ collisions on Li(2s) but their origin due to electron swaps went unrecognized [9].…”

Energy-dependent relative charge transfer cross sections of Cs++ Rb(5s, 5p)

“…al. [17], this feature could be a consequence of the number of swaps the electron undergoes across the potential energy saddle during the charge exchange process. …”

“…Experimental results were found to be in excellent agreement with molecular closecoupling calculations. Also, using similar MOTRIMS techniques, single electron transfer and ionization in collisions of N 5+ and Ne 8+ with Na(3s, 3p) were investigated both experimentally and theoretically at collision energies from 1 to 10 keV/amu [16,17].…”

Strong sensitivity of x-ray emission lines following charge exchange between highly charged ions andH(1s)in weakly screened media

“…Two quantities are evaluated for this task: the distribution of impact parameters relevant for charge exchange and the range of projectile z-coordinate values (coordinate along the beam axis) in which the charge exchange reaction takes place. In practice, we define this region by identifying the first and last crossing of the potential saddle by the electron [26,27]. These quantities are, respectively, shown in Figs.…”