Hyperfine structure investigation of spectral lines of the praseodymium atom in the visible spectral region

• Discovery of 26 previously unknown energy levels of atomic praseodymium (Pr I) applying laser-induced florescence (LIF) spectroscopy • Determination of their hyperfine structure constants A • 57 known and 77 up to now unknown Pr I lines, showing up in the used FT spectra, could be classified with help of the new levels • Further 62 transitions could be verified either via laser-ecxitation or observation of LIF 26 new energy levels (7 of even, 19 of odd parity) of Pr I were discovered using laser induced fluorescence (LIF) spectroscopy. Values of the magnetic hyperfine interaction constants A of these levels are presented. 57 known but up to now unclassified lines could be classified as transitions to the new levels. Moreover, 77 lines which were never mentioned in the literature but could be identified in our FT spectra, are classified. Finally, 62 other lines could be detected either as excitation or fluorescence channels, but too weak to appear in the FT spectra. For some lines the classification given in the literature appeared to be erroneous.