[en] This study investigates the collision induced excitation of atomic hydrogen into the n = 3 state with respect to the linear polarization fraction of the Balmer H_α line. We used electrons with energies between 80 eV to 3 keV, protons and singly charged helium ions in the energy range from 40 keV to 1 MeV. Difference for electron and ion excitation at equal velocities could be explained within a first Born approximation. Comparisons with theories for electron and ion impact are discussed. (Author)

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No abstract available

[en] Total cross sections for the production of He⁺(2p) in collisions of H⁺ and e^- with He at energies from 75 to 800 keV and from 0.8 to 7 keV respectively were measured. The ratio of the cross sections for He⁺(2p) production and for single ionization is discussed to investigate the contribution of electron correlations in the two-electron transition leading to He⁺(2p). For the first time the impact of H₂⁺ and H₃⁺ ions in comparison with H⁺ impact has also been studied for the energy range mentioned above. (author)

No abstract available

No abstract available

[en] The 3s vacancy production in Ar⁺-He and Ar⁺-Ar collisions has been studied at impact energies of 100 keV to 550 keV. A comparison is made for the Ar⁺-He system with theoretical calculations based on the quasi-molecular model. (Auth.)

[en] We have investigated the collisional excitation of hydrogen atoms by protons and multiply charged ions at intermediate velocities applying the optical method. The population of the np levels (n=2,...,6) has been determined for a variety of projectiles with charge states q ranging from 1+ to 11+ and scaled velocities υ/√q between 0.7 and 5.6 au. The cross sections are shown to fulfil the scaling relation σ/q=f(υ²/q) with respect to the projectile charge q and velocity υ for q≥3. The relevance of scaled intermediate velocities for a classification of excitation mechanism is pointed out. (Author)

[en] We have investigated the collisional excitation of He by protons and multiply charged ions at intermediate velocities applying the optical method. The population of the magnetic sublevels of He 4¹D has been determined using level-crossing techniques for a variety of projectiles with charges ranging from 1+ to 23+ and velocities between 1 au and 7 au. The relative excitation cross sections of the Zeeman substrates turn out to be universal functions of the projectile velocity and charge. (author)

[en] Polycrystalline Al and Mo targets have been bombarded with Ne⁺ ions of 600 keV energy and current densities of up to 30 μA/cm², the background vacuum being 10^-6 torr. Spectra emitted by sputtered atoms are registered simultaneously in the spectral range from 700 to 1400 A and the visible range. First results of measurements of intensity are presented and discussed