Two-step resonant photoionization spectra of Sm atom

Resonant ionization spectra of Sm atom are Studied with a two-step photoexcitation and photoionization method. Two different excitation paths are carried out as the following: In the path 1, the first laser whose wavelength is fixed at 478.44 nm excites the Sm atom from the 4f(6)6s(2)[F-7(1)] state to the 4f(6)6s6p[D-7(1)] state, and then the second laser whose wavelength lambda(2) is scanned front 480 nm to 530 run excites it further to the high-lying state with even parity. In the path 2, the first laser whose wavelength is fixed at 574.81 nm excites the Sm atom from the 4f(6)6s(2)[F-7(2)] state to the 4f(6)6s6P[(5)G(3)] state, and then the second laser whose wavelength lambda(2) is scanned from 460 nm to 470.5 nm excites it further to the high-lying state with even parity. These Sm atoms in the high-lying state are probed by photoionization via the third laser. All together 26 and 76 states of Sm atom in the 39465-39932 cm(-1) and the 40000-42010 cm(-1) energy region, respectively, have been detected below the first ionization limit. The energy levels and relative strengths of these states have been determined. Among them, 51 states are newly discovered, while the rest agree well with the values published in literature. In addition, efforts are also made to determine their spectral designation.