Hyperfine structure odd-parity configurations of the terbium atom, Part I: Levels with small J

The paper presents the results of measurements of the hyperfine structure for electronic levels belonging to odd configurations in the terbium atom with a small quantum number J. Laser spectroscopy with laser- induced fluorescence detection was used in the measurements. The hyperfine structure of 32 terbium lines was measured in three spectral regions. The hyperfine structure constants were determined for 20 levels with quantum number J values between 1/2 and 7/2, of which 13 levels have not been studied so far. For the remaining 7 levels, the precision of the constants was improved.