Double capture in the O8++He collision investigated by electron spectroscopy (80 keV, 10')

Double capture into (3, n) autoionising states of O 6+ is observed in the O 8+ +He collision by electron spectroscopy at 80 keV, 10'. A comparison with the authors' theoretical positions and lifetimes allows to identify (3, 3) states as well as three groups of (3, 4) states; some theoretical (3, 5) values are also given which agree with the corresponding experimental line position. By a fitting procedure of the (3, 3) part of the electron spectrum, relative weights of (3, 3) states are determined and it is found that the (3, 3) 1 G e state accounts for 42% of the double capture into the (3, 3) configuration; also 24% of the double capture into the (3, 4) configuration is found to occur into the highest angular momentum states 1 H o (1) and 1 G e (2). A comparison of the present experimental findings with earlier data the authors have obtained for the N 7+ +He and Ne 8+ (1s 2 )+He systems, is made. The influence of the core of the multicharged ion is studied by comparing O 8+ and Ne 8+ (1s 2 ) results; it is found that only the L distributions differ from each other, the n distribution and total cross section being the same. The total double capture cross section is found to be large and it is compared with available experimental and theoretical data.