INTENSITIES OF THE NEONLIKE IRON (FE-16+) 2P53S-2P53P AND 2P53P-2P53D TRANSITIONS IN SOLAR-FLARE SPECTRA

We present relative spectral line intensities for 16 3s-3p and 3p-3d transitions in the neonlike ion Fe16+, obtained from solar-flare spectra. The spectra were obtained by a Naval Research Laboratory slitless spectrograph flown on the Skylab manned space station. The results are of relevance to x-ray-laser experiments involving collisional pumping of excited states of neonlike ions, and to the analysis of solar-flare spectra. The relative line intensities are measured to an accuracy of about 30%. The measured line intensities are compared with theoretical line intensities calculated assuming electron collisional excitation within the Fe16+ ion followed by deexcitation and radiative decay. The measured and theoretical intensities agree to within less than a factor of 2 for all but one line. The important J = 0 lines (3p 1S0-3s 1P1,3s 3P1) at 254.87 and 204.65 angstrom are about a factor of 1.4 weaker than predicted, which is almost within experimental error. The 3s 3P2-3p 3S1 line at 409.69 angstrom is 2.3 times weaker than predicted, and this is unexplained.