In this work, we studied the photon emission in the visible light range for Xeq+ ions of different charge states (10 ≤ q ≤ 21) bombardment on an aluminum target at 410 keV. During the interactions, the spectra in wavelength range 300–500 nm are recorded, including the photons from Al atoms and neutralized Xe+ ions. The yield of the visible light strongly depends on the projectile charge states. Its variation tendency with the charge states is similar to that of the potential energy variation. In addition, the experimental results also indicate that when the incident charge state is less than the critical charge state, it obeys the staircase classical-over-barrier model.
