High-Resolution Measurements of Photoionization of Ions Using Synchrotron Radiation

Measurement of absolute cross sections for photoionization of ions has become feasible by merging a well‐collimated ion beam with a monochromatic beam of synchrotron radiation. An electron cyclotron resonance (ECR) ion source permits such measurements to be extended to multiply charged ions, and makes possible systematic studies along isoelectronic sequences. The evolution of atomic spectra along such sequences is commonly studied theoretically, but the predictive ability of the theoretical methods remains largely untested. Absolute cross‐section measurements are presented for the first three ionic members of the isoelectronic sequence of nitrogen (O+, F2+ and Ne3+).