Laboratory study of K-shell photoionization of oxygen and oxygen hydrides ions

The interpretation of the spectra sent by satellites required the knowledge of many atomic data, including photoionization cross sections or energy and oscillator strength of bound-bound transitions for many ions, over a broad photon energy range going from infra-red to x-rays. These data are mainly provided by theoretical results using state-of-the-art methods like $R$-matrix. Recently, discrepancies have been observed between the calculated energy of the K$\alpha $ transitions in atomic oxygen and its ions and those determined from the satellites observations [1-2]. The results of the experimental studies of K-shell photoionization of oxygen ions performed at the French synchrotron radiation center SOLEIL will be presented [3]. A merged-beam setup installed on the PLEIADES beam line allows for the determination of absolute photoionization cross sections and transitions energy on singly- and multiply-charged ions in the 10-1000 eV photon energy range. The first results obtained with this setup on oxygen hydrides will be also presented. [1] E. Gatuzz et al, ApJ 768, 60 (2013) [2] F. Nicastro et al, MNRAS (2016) [3] J.M. Bizau et al, Phys Rev A 92 023401 (2015)