Studies on the hyperfine structure of La I in a hollow-cathode discharge tube

Hyperfine structures (HFS) of La I are reported using Doppler-free intermodulated fluorescence, Doppler-limited laser-induced fluorescence and optogalvanic spectroscopy in a homemade hollow-cathode discharge tube. The A and B constants for the levels at 20197.34, 21447.86 cm-1 and A constants for the levels at 19379.40, 18156.97, 24910.38 and 24409.68 cm-1 are, to our knowledge, reported for the first time. A linewidth less than 40 MHz and the different resolutions of fluorescence and optogalvanic spectroscopy are observed. (author)