K x-ray production in H-like Si13+, S15+, and Ar17+ ions colliding with various atom and molecule gas targets at low collision energies - art. no. 042712

K x rays have been observed in electron capture processes of H-like Si13+, S15+, and Ar17+ (1s) ions colliding with various atom and molecule gas targ ets over the collision energy of 1-70 keV/u. These K x rays are the final r esults of cascade-down to the ground (1s(2)) state from highly excited stat es formed through electron capture. It has been found that at low energies (< 10 keV/u) the cross sections for the production of K x rays are nearly c onstant, and decrease slowly when the collision energy is increased. The cr oss sections also have been found to increase roughly with the inverse squa re of the ionization energy of the targets. It is also noted that the inten sity ratios of the K<beta> line to the K alpha line increase slightly as th e ionization energy of the target increases, suggesting that an electron is captured in different (nl) states in different targets. These ratios are f ound to decrease slightly as the collision energy increases. The measured K x-ray production cross sections also have been compared with total electro n-capture cross sections based upon an empirical formula, and it has been f ound that, on average, roughly two-third of total electron capture processe s result in K x-ray emission, with the remaining one-third ending at the me tastable state level after electron capture without emitting K x rays.