PECULIARITIES OF 221.1-NM Tl I (6s(2)6p P-2(1/2)0 - 6s6p(2) P-4(1/2)) SPECTRAL LINE EXCITATION AT ELECTRON-ATOM COLLISIONS

The excitation function for the 221.1-nm spectral line of a thallium atom originating from the 6s6p(2) P-4(1/2) level at electron-atom collisions has been studied in the energy range from the excitation threshold to 16 eV and with an energy spread of about 0.7 eV. A number of structural features related to the autoionizing states and the shape resonances has been found in the excitation function above the ionization threshold.