induced by synchrotron radiation.*

The single photoionization of Cl III induced by radiation is being studied both, theoretically and experimentally, in the radiation energy range from below ionization threshold up to 20 eV above it. For the theory, ab-initio R-matrix method is being implemented. For the experiment, high resolution synchrotron radiation from the Advanced Light Source at the LBNL was merged with an ion-beam of Cl²⁺ to generate Cl³⁺ ions which intensity was monitored alongside with other relevant parameters. Several resonant features lying above a non-resonant  background below and above threshold have been observed and, will be discussed with the help of the R-matrix theory.