Excitation Mechanisms in Moderate-Energy K⁺–Ne Collisions

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By means of differential scattering spectroscopy, excitation processes in K⁺–Ne collisions have been studied at laboratory collision energies of 350≤E_lab≤2000 eV. Doubly differential cross sections σ(Θ)_k have been measured over a wide range of center-of-mass angles, 3≤Θ≤176°, by detecting all the scattered particles (K⁺, K, Ne⁺, Ne), where subscript k means exit channels in the reactions. Excitations were observed appreciably at reduced angles of τ>4 keV deg and collision energies of E_lab≥1000 eV. At 1000≤E_lab<1500 eV, only one-electron excitations have been found, while at E_lab≥1500 eV, two-electron excitation has been observed in addition to one-electron excitations. The electronic transitions are classified into two types depending on the excitation mechanism. One is the one-electron transitions taking place at internuclear distances of R<R_C1=1.08 Å, and the other is one- and two-electron transitions occuring at R<R_C2=0.45 Å. Both the distances R_C1 and R_C2 are nearly equal to those for the isoelectronic system of Na⁺–Ar studied previously.