K-shell photoionization of atomic anions

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Negative atomic ions play an important role in low-temperature plasmas such as the upper atmosphere or the interstellar medium and also in technical applications. Here, K-shell photodetachment of negatively charged oxygen and sulfur ions will be experimentally investigated using a unique combination of an intense ion beam with tunable synchrotron radiation from one of the world's brightest third generation synchrotron radiation sources, i.e., PETRA III in Hamburg. Absolute cross sections for multiple detachment will be measured as a function of photon energy and, in collaboration with leading theoretical physicists, be interpreted by large-scale atomic-structure calculations. In light of already published first results, it is expected that the proposed work will greatly enlarge the body of data on inner-shell photo-processes (including double K-hole production) involving atomic anions. The results will provide detailed insight into the structure and dynamics of ephemeral multiply excited states in weakly bound small quantum systems. Moreover they will be relevant for other fields of research such as low-temperature plasma physics, physics of planetary atmospheres, and the chemistry in interstellar gas clouds.