We elaborate the quantum-mechanical analysis using the two-state vector model to investigate the formation of intermediate Rydberg states of multiply charged ions (core charge Z ≫ 1, principal quantum number nA ≫ 1) interacting with solid surfaces in the grazing incidence geometry. For the fixed initial and final states of the active electron, the two wavefunctions are used to describe the transitional electron state at the time t. Considering the projectile motion classically, the effect of projectile velocity is taken into account in accordance with Galilean invariance. The population probabilities of the intermediate Rydberg states are obtained in the analytical form, which enables an analysis of the localization and the selectivity of the process, for various ion–surface parameters. Ions ArZ+, KrZ+ and XeZ+ with Z ∈ [5, 35] interacting with Al-surface are considered as an example. The results are compared with the classical overbarrier predictions and the measured kinetic energy gain due to the image acceleration of the ions. It is demonstrated that the ionic velocity influences the ion–surface distance at which the formation of the particular intermediate Rydberg state is mainly localized, as well as the probability for this formation.

Electron-impact excitation of the CO molecule has been investigated by use of a crossed beam double trochoidal electron spectrometer. Forward and backward scattered electrons from the 2 ⌸ resonance are analyzed. In order to separate these two contributions, electron beam modulation and time-of-flight detection of scattered electrons have been introduced. Backward electrons are additionally delayed in time by introduction of a decelerator device. The operation of this device is tested by a measurement performed on the 2 ⌸ g resonance in N 2 molecule. The ratio of forward-to-backward scattered electrons from the 2 ⌸ resonance in CO is found to be equal to 1, and thus the angular distribution of scattered electrons to be symmetric relative to 90°. This conclusion is compared to existing angular distribution measurements and theoretical predictions.

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