Oxygen K-shell photoabsorption spectra of photoionized CO₂ plasmas

We report oxygen K-shell photoabsorption measurements in CO₂ plasmas, using a table-top laser produced plasma soft x-ray (SXR) and extreme ultraviolet source. Significant differences are observed between the photoabsorption spectra of the neutral CO₂ molecule and photoionized CO₂ plasmas, as new spectral features emerge in the case of the latter. These features are attributed to $1s⟶2p$ photoexcitation in O, O⁺, O²⁺ species identified with the aid of calculations performed with the Cowan suite of atomic structure codes. Such signatures of atomic ions in the photoionized plasma point to the fragmentation of the parent molecule upon absorption of an SXR photon. (paper)