In this paper, we present experimental and theoretical studies on the interference between resonant and nonresonant photorecombinations for the main resonances of ground-state He-, Be-, B-, C-, N-, and O-like W ions. Experiments were done using a fast electron energy scanning technique at the upgraded Shanghai electron-beam ion trap. Asymmetric resonances were observed, and their Fano factors, which measure the interference degree, were determined. The calculations were done under the framework of Fano's theory by using the flexible atomic code, in which the relativistic configuration interaction method was employed. Among the nine resonances studied in this work, eight experimental results agree with the calculation within experimental uncertainties. But the experimental result for the resonance of Be-like W ions, through the intermediate state of ${\left[{\left(1s2s^{2}2p_{1/2}\right)}_{1}2p_{3/2}\right]}_{5/2}$, deviates from its corresponding theoretical result by 1.3 times experimental uncertainty.

• Received 14 January 2016

DOI:https://doi.org/10.1103/PhysRevA.93.032707