Spectrum and Term System of Doubly Ionized Fluorine, F III

The analysis of the spectrum of doubly ionized fluorine, F III, has been revised and extended by using a sliding spark as a light-source. Many new lines (about 700) are identified, particularly in the regions 742-2 206 Å and 3 436-9 078 Å, where no lines were previously known. The nf and ng levels have been found and compared with those derived from the theoretical expressions for pair coupling. Altogether about 150 new energy levels are established. The sextet terms are connected with the other terms, giving for the quantity x in "Atomic Energy Levels" the value +21.6 cm-1. The first ionization limit (3 P 0) has been determined to 505 777 ± 5 cm-1.