Transient Molecular-Ion Formation in Rydberg-Electron Capture

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

“…For the present Garvey representation of the target, the position of the saddle can be parametrized as: (4) which is the saddle position predicted by the Classical Overbarrier model for the hydrogen target. The parameters a =0.56, b= 0.12, z=1.37 and N=0.39 represent the correction terms introduced by the short range component of the Garvey potential.…”

“…During the last 50 years, charge exchange studies of atom-atom [1], ion-alkali [2,3] and ion-Rydberg collisions [4] at the total cross section level have systematically indicated the presence of oscillatory structures which were either interpreted as due to a region of stationary phase in the difference between the incident and outgoing channels or, in a classical picture, the number of swaps the electron undergoes across the potential saddle before it is captured by the projectile [5]. A more detailed inspection of the physical mechanisms responsible for those oscillations was experimentally prohibitive in those days while the limited computational facilities also restricted the theoretical capabilities to further refine our understanding of those collision processes at the highly differential level.…”

Effect of static electric field on cross sections in antiproton impact ionization of atomic helium

“…The classical similarity [38] and correspondence principle provide the essential base for the classical as well as semiclassical methods such as the Classical Trajectory Monte Carlo, classical over barrier model and semiclassical impact parameter methods, that are able to describe most features [25] of the charge transfer and ionization processes occurring in ion-atom collisions even at low impact velocities. It has been shown to work quite successfully, and in particular, the case of ion-atom collisions at intermediate and low energies in several CTMC applications [25][26][27][28][29][30][31][32][33][34][35][36][37]. Also, it has been widely used for the single valance electron atom target by several workers [25][26][27][28][29][30][31][32][33][34][35][36][37].…”

“…Therefore, it would be worthwhile to attempt for understanding the effects of the external electric fields on the ionization of helium atoms with antiproton collisions. The Classical Trajectory Monte Carlo (CTMC) method is a well tested method to simulate inelastic ion-atom collision at intermediate energies [25][26][27][28][29][30][31][32][33][34][35][36][37]. The classical similarity [38] and correspondence principle provide the essential base for the classical as well as semiclassical methods such as the Classical Trajectory Monte Carlo, classical over barrier model and semiclassical impact parameter methods, that are able to describe most features [25] of the charge transfer and ionization processes occurring in ion-atom collisions even at low impact velocities.…”

Creating and probing coherent atomic states

“…Subsequently, the production a of more general class of wavepackets have been studied which consist of a dispersive coherent superposition of atomic states and do not satisfy the minimum uncertainty condition. Examples of signatures of coherences associated with the electronic time evolution in atomic collisions include, from very old ones to very recent ones: Stiickelberg oscillations [2], Stark beats [3], and swapping oscillations [4]. Only in recent years it has become possible to generate transient quasi-classical wavepackets which remain well localized for a long period of time.…”