New odd-parity fine structure levels of Pr I with J = 1/2, 3/2 and 5/2

Abstract In continuation of our previous publication on experimental laser spectroscopic investigations of the spectrum of the praseodymium atom in the visible region, the present paper reports the discovery of 65 new odd-parity fine structure levels of Pr I. Pr I atoms sputtered in a low-pressure hollow cathode discharge lamp were excited using tunable laser light. The excitation wavelengths were selected using a Fourier transform spectrum. In these investigation, 411 spectral lines were classified as belonging to the newly discovered fine structure levels. From the observed hyperfine structure patterns, the hyperfine constants of the combining levels could be determined. For the majority of the newly discovered levels their existence and the obtained hf constants were verified by investigation of two or several transitions from different lower known energy levels. Levels introduced due to only one excitation are discussed in more details.