New even-parity energy levels of the neutral Lanthanum atom derived from difficult to interpret measurements

We report the discovery of seven even-parity energy levels of the Lanthanum atom. These levels are derived from experimental results which are quite difficult to interpret, since most of the investigated structures appear in complicated blend situations. 17 spectral lines can be classified as transitions in which these levels are involved. Further we could improve the J-values and hyperfine structure constants A of two earlier published levels due to the investigation of additional lines.