Photoabsorption spectrum of Mg i in the range 226–170 Å (54–70 eV)

The photoabsorption spectrum of Mg i has been observed in the spectral region 226–170 Å (54–70 eV) using synchrotron radiation as a background source. The one-electron excitation levels associated with the series: 1s2 2s2 2p63s2 1So → 1s2 2s2 2p5 [2P3/2,1/2]3s2n s, n d were observed as well as 29 two- and three-electron excitation resonances. A critical analysis of the one-electron excitation spectrum was made and classifications for all the multiple electron excitations have been suggested on the basis of their quantum defects to known limits in Mg ii.