The second spectrum of nickel (Ni II)

Abstract

An analysis of Ni II based on 4300 observed lines is presented. The low structures are 3<i>d</i> ⁹ <i>, 3d</i> ⁸ 4<i>s</i> and 3<i>d</i> ⁷ 4<i>s</i> ² which are now complete except for 3<i>d</i> ⁸(¹S)4<i>s</i> ²S and 3<i>d</i> ⁷ 4<i>s</i> ^{2 2}P_½ and the higher of the two ²D terms of 3<i>d</i> ⁷ 4<i>s</i> ². Long series occur such as 3<i>d</i> ⁸4<i>s</i> to 9<i>s</i>, 4<i>d</i> to 8<i>d</i>, 4<i>f</i> to 7<i>f</i>, 5<i>g</i> to 7<i>g</i>. The analysis also includes many terms of the complex structure 3<i>d</i> ⁷ 4<i>s</i> 4<i>p</i> but only 55 percent of the levels within reach of the hollow cathode source have been found. The identification of the levels of 3<i>d</i> ⁸ 4<i>d</i> and 5<i>d</i> was assisted by the calculations of N. Spector. The 4<i>d</i> ⁷ 4<i>s</i> ² levels were calculated by Y. Shadmi, who also provided calculated positions for all the levels of 3<i>d</i> ⁷ 4<i>s</i> 4<i>p</i> without which much of the analysis would have been impossible. The 3<i>d</i> ⁸ <i>ns</i> and 3<i>d</i> ⁸ <i>nd</i> series give a limit of 146532.0 but the 3<i>d</i> ⁸ <i>ng</i> series gives 146541.56. The latter has been adopted though no explanation of the discrepancy has been found.