Energy Dependence of the Line Ratio I(233.9 Å)/I(243.8 Å) in Fe xv Observed with an Electron Beam Ion Trap

We present the energy dependence of the intensity ratio between the 3s3p (3) P (2)-3s3d (3) D (3) transition at 233.9 angstrom and the 3s3p (1) P (1)-3s3d (1) D (2) transition at 243.8 angstrom in Fe xv studied with an electron beam ion trap over an energy range that spans resonance excitation regions. Clear resonance structures are observed in the electron energy range of 400-600 eV. The energy dependence obtained in the experiment is compared with a collisional-radiative model calculation, including resonance excitations, and overall agreement is found. It is shown that the ratio strongly reflects the population of the 3s3p (3) P (2) metastable state, which is the lower state of the 233.9 angstrom transition.

Automated summary

We investigate the energy dependence of the intensity ratio between two transitions in Fe xv, and observe resonance structures in the range of 400-600 eV. The experimental results are compared with a collisional-radiative model calculation, showing overall agreement. The ratio is shown to reflect the population of a specific metastable state.