Visible light emission induced by Krq+ (4 ≤ q ≤ 9) ions colliding with the Cu surface

In this paper, we report visible light emission from 320 keV Krq+ (4 ≤ q ≤ 9) ions on the Cu target. The wavelength range measured is from 300 nm to 656 nm. Two Cu I spectra deriving from different initial states and one Kr I line are detected. Specifically, the two Cu I lines belong to transitions 3d104p(2P03/2) − 3d104s (2S1/2) at 324.78 nm (A) and 3d104p(2P01/2) − 3d104s(2S1/2) at 327.42 nm (B), respectively, and the photon yield ratio of spectra lines (A) and (B) are about 2:1. The Kr I line belongs to transition 4s24p5(2P03/2)11d 2[3/2]0 − 4s24p5(2P03/2)5p 2[1/2] at 486.12 nm (C). In addition, the experimental results show that the photon yields of all lines are increasing with the charge state increase.