Two-step resonant photoionization spectra of Sm atom

Abstract

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 478.44nm excites the Sm atom from the 4f66s2［7F1］ state to the 4f66s6p［7D1］ state，and then the second laser whose wavelength λ2 is scanned from 480nm to 530nm excites it further to the high-lying state with even parity. In the path 2, the first laser whose wavelength is fixed at 574.81nm excites the Sm atom from the 4f66s2［7F2］ state to the 4f66s6p［5G3］ state，and then the second laser whose wavelength λ2 is scanned from 460nm to 470.5nm 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.