Observation and analysis (synthesis) of X-ray spectrum originated from electron capture of low-energy, highly charged Xe^q+ (q = 26–43) ions in single collisions with Ar atom

X-rays have been observed in collisions of low-energy (keV/u), highly charged Xeq+ (q = 26-43) ions with neutral Ar atoms. These X-rays are understood to be produced through electron capture by highly charged projectile ions from target atoms, the electrons then cascade down to the ground state. It is clearly noted that the most intense X-ray peaks correspond to M-shell - N-shell transitions with different numbers of M-shell vacancies and that X-ray intensities decrease significantly toward high energies near the ionization limit. This observation indicates that the direct transition of an electron captured in a highly excited state to M-shell vacancies is negligibly small. To obtain a better understanding of X-ray production mechanisms, we tried to synthesize the expected X-ray spectrum and compare that with the observed spectrum. The synthesized spectra were found to reproduce the observed spectra reasonably well.