High resolution spectroscopy of prompt and metastable decaying levels in highly ionized argon,especially of the metastable3 P 2-state of Ar16+ and the4 P 5/2-state of Ar15+

Besides the prompt x-ray emission of Ar-ions, the metastable decay of the heliumlike³ P ₂- and the lithiumlike⁴ P _5/2-levels of highly ionized Ar¹⁶⁺ and Ar¹⁵⁺ atoms has been observed in a foil-excited beam using a flat-crystal spectrometer. Due to the highx-ray energy resolution of the spectrometer the two³ P ₂ →¹ S ₀ and⁴ P _5/2 →² S _1/2 transitions could be resolved. The experiment yielded (3128 ±2) eV for the³P₂ → and (3091 ± 2)eV for the⁴ P _5/2 →² S _1/2 transition energy respectively. Using a time of flight technique the lifetimes of the³ P ₂- and the⁴ P _5/2-states were determined to be (1.44 ±0.09)ns and (0.66 ± 0.05) ns.