The high resolution spectrum of the 2p(5)3s-2p(5)3p-2p(5)3d transitions in
neon-like Ar IX ion was investigated using a fast capillary discharge with
inductive storage as a source. The previous analyses of these transitions w
ere revised on a basis of accurate semi-empirical interpolation along the n
eonlike sequence. The complete energy structures of 2p(5)3l configurations
were measured using the improved transition wavelengths and the newly ident
ified transitions. The present analysis is confirmed by the internal consis
tency of obtained spectroscopic results and by the monotonous behavior of e
nergy parameters along the isoelectronic sequence.