Investigation of autoionization spectra of Sm atoms using an isolated-core excitation method

Using the isolated-core-excitation scheme and three-step laser resonance ionization spectroscopy approach, this paper, for the first time, has systematically investigated the autoionization spectra of atomic Sm, belonging to the 4 f⁶6pnl and 4f⁵5d6snl (l=0, 2) configurations. In the experiment, the first two tunable dye lasers are employed to excite the Sm atom from its initial state to the different 4f⁶6snl bound Rydberg states, then the third dye laser is scanned to drive the atom to the doubly-excited autoionizing states. With the above excitation scheme, the measured transition profiles of the autoionizing states are nearly symmetric, from which the level energies and widths can be easily obtained.