Spectroscopic study of doubly excited Na-like argon ions

Doubly excited Ar 7+ (2p 5 3s nl) 2,4 L ions are produced in th charge exchange collision Ar 8+ (2p 5 3s) 3 P 0.2 +H 2 at 2 keV amu -1 . Their radiative stabilisation is observed in the wavelength interval 4-5.3 nm. It is shown that the spectrum consists of lines arising from states produced in the capture into (2p 5 3s5l) 2,4 L and decaying to 2p 6 5 l 2 L and from states such as 2p 5 3s3l 2,4 L populated by cascades and decaying to 2p 6 3l 2 L. These Na-like Ar satellite transitions are situated in wavelength relative to the mother Ne-like Ar transitions 2p 5 3s 1 P 1 to 2p 6 1 S 0 and 2p 5 3s 3 P 1 to 2p 6 1 S 0 observed as the end of the cascade following the charge-exchange collision Ar 9+ +H 2 to Ar 8+ +H 2 + .