Laser induced fluorescence spectroscopy used for the investigation of Landé gJ- factors of praseodymium energy levels

•New method of Lande gJ factors measurement was used for observation of Pr I spectra.•By the use of LIF technique precise spectroscopic data have been obtained; new experimental gJ factors have been determined for 71 energy levels of Pr I.•Hfs and gJ data for Pr I levels have been tested and corrected.

Laser induced fluorescence (LIF) spectroscopy was used for the investigation of structures of 52 spectral lines of Pr I in the wavelength range 561.3 - 613.9 nm. As a source of free Pr atoms a hollow cathode discharge lamp was used. We monitored selected LIF signals appearing when the laser beam excites the hollow cathode plasma. LIF spectra were recorded in the presence of a magnetic field of about 800 G produced by a permanent magnet for two linear polarizations of the exciting laser beam. We have determined for the first time Landé gJ- factors for 71 levels of neutral Pr and reinvestigated data for several other levels.