Interference between direct-excitation and charge-exchange collision channels leading to oscillations that are 180° out of phase has been observed in low-energy ${\mathrm{N}}^{+}$-Ne, ${\mathrm{O}}^{+}$-Ne, ${\mathrm{Na}}^{+}$-Ne, and ${\mathrm{Mg}}^{+}$-Ne collisions. Strong polarization effects are present in the optical radiation from excited states in neon for all four systems. For $L=1\mathrm{}$, the polarization data show that the oscillatory structure is predominantly due to population of the magnetic sublevels $m=\pm 1$.

• Received 19 July 1973

DOI:https://doi.org/10.1103/PhysRevLett.31.739