The radiative and autoionization decay channels of oxygen metastable ionic states have been investigated with beam-foil spectroscopy. Relative branching ratios of the 1s2s2${\mathit{p}}^4$${\mathrm{P}}_{1/2,3/2}^{\mathrm{o}}$ states of ${\mathrm{O}}^{5+}$ to the J=5/2 level have been determined. Radiative and autoionization rates of the J=1/2 and 3/2 fine-structure levels are extracted by using the calculated fluorescence yield of the J=5/2 level of Chen, Crasemann, and Mark [Phys. Rev. A 27, 544 (1983)] and the measured total lifetimes corrected for cascades. The study of the delayed electron emission is extended in nitrogen and carbon ions, where transition rates of the dominating autoionization channel of the 2 ${}_{}{}^4{}_{}{}^{}P_{1/2}^{}{}_{}{}^{}$,${5/2}^{\mathrm{o}}$ states have been determined directly from the experimental lifetimes corrected for cascades.

• Received 5 April 1989

DOI:https://doi.org/10.1103/PhysRevA.40.2359