Zeeman-hyperfine structures and isotope effect in the spectrum of Tl I

The Zeeman structures of seventeen lines of 205Tl I (Z=81) covering the UV-NIR spectral range (351.92-1151.28) nm were investigated. Landé gJ-factors for eighteen levels were determined for the first time. Furthermore, we have performed fine structure studies for both even- and odd-configuration levels and determined the relevant parameters. For the 6s6p2 configuration we have refined the suggested level energies and predicted positions for missing levels. With regard to hyperfine structure (hfs), we have justified the surprisingly huge value of the magnetic hfs constant A(6s210s). Moreover, we have extracted the single-electron hfs constant parameter values for the lowest even-parity configurations of 205Tl I; for instance a10s10(6s210s)=1015(9)MHz and a6s10(6s6p2)=217306(205)MHz. Regarding isotope shift analysis we have observed that Dirac-Fock calculations, preferably chosen to take into account the contribution of the p1/2 contact-electron, are in good agreement with experimental data for low-lying levels of each configuration under study.