Excitation of resonance transitions in a thulium atom by slow electrons

We experimentally studied the excitation of resonance transitions in a thulium atom in electron-atom collisions. At an electron energy of 50 eV, we measured 52 TmI excitation cross sections. We recorded 41 optical excitation functions in the electron energy range from the excitation threshold to 200 eV. The measured cross sections are, on average, a factor of 1.09 larger than their preceding experimental values but a factor of 2.41 smaller than their theoretical values.