Polarized-Photon, Scattered-Ion Coincidence Study of Mg+ Collisions with He, Ne, and Ar
The impact-parameter dependence of the Mg II (3s ← 3p) emission has been studied for 3–15 keV Mg+-He, Mg+-Ne, Mg+-Ar collisions by means of photon, scattered-particle coincidence measurements, including polarization analysis. The resonance excitation can be described by means of two mechanisms: At low collision energies, the Mg II (3s → 3p) excitation occurs at molecular curve crossings, whereas direct excitation dominates at higher energies. The direct mechanism is essentially the same for all three collision systems and exhibits a high degree of coherence. The quasimolecular mechanism to a large extent depends on the asymmetry of the collision. The asymmetric Mg+-He, Mg+-Ar systems show substantial coherent excitation, whereas the resonance level is noncoherently excited in the quasisymmetric Mg+-Ne collision.
KeywordsImpact Parameter Emission Probability Emission Cross Section Resonance Level Collision System
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