New energy levels of La I found by laser spectroscopy

Laser spectroscopy and optogalvanic detection was applied to investigate up to now unclassified or even unknown spectral lines of atomic lanthanum (La I). The exciting laser light had wavelengths between 4300 and 6800 angstrom. We report the discovery of seven new energy levels. One additional level turned out to be already known, but with wrong angular momentum. Altogether 53 spectral lines could be classified as transitions of these eight levels. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

Laser spectroscopy and optogalvanic detection were used to investigate previously unclassified or unknown atomic lanthanum (La I) spectral lines, resulting in the discovery of seven new energy levels and one known level with incorrect angular momentum. In total, 53 spectral lines were classified as transitions of these eight levels.