Autoionization spectra of Sm atom

Abstract

Spectra of autoionizing states of the Sm atom in an energy region between 45948.9 cm−1 and 46943.6 cm−1 are systematically investigated by a three-color multi-step resonant excitation scheme with three different excitation paths. The three intermediate states, 4f 66s7s 7F3, 4f 66s7s 7F4, and 4f 66s7s 9F5 are employed for the three paths, respectively. Based on precise calibration of wavelength, the level energies of 112 autoionizing states are determined with the line widths and the relative line intensities of the related transitions. The possible influence of configuration interaction on the line shape of autoionizing state is also discussed. In addition, a unique value of J, the total angular momentum, is assigned to all detected states by comparing the three spectra obtained with the different excitation paths.

Branching ratios of autoionization from Eu 476p1/26d [J] autoionizing states

“…The simultaneous excitations of the two channels, to the 4f 7 6p 1/2 6d autoionizing states and to the 4f 7 6s εp, εf continuum states, induce the interference effect between them, resulting in the Fano-type line shapes. Due to the violation of the ICE scheme, the advantage of the technique partially vanishes, which means the ICE scheme is only valid down to the n = 7 state, which was confirmed by the experiments on the Ba [18] and Sm [21] atoms. The invalidity of the ICE scheme for the n = 6 state 083203-3 is an important limit to experimental studies of autoionizing states.…”

“…As a powerful three-step excitation method, the ICE scheme has been used extensively to study the autoionizing states of alkaline-earth atoms [18,19] and rare-earth atoms. [20,21] For instance, the autoionization spectra of the Ba 6p 1/2 nd states, with n = 7-15, exhibit the Lorentzian profiles. [18] This is understandable, because for the higher-n 6p 1/2 nd autoionizing states, the nd Rydberg electron is too far from the core, which is isolated during the 6s + → 6p + 1/2 excitation.…”

The VMI study on angular distribution of ejected electrons from Eu 4f76p1/26d autoionizing states

“…[16] The autoionization spectra shown in Fig. 4 are by no means standard Lorentzian profiles, the Fano type instead, indicating the breakdown of the ICE mechanism, which is valid for the higher-n 6pnl autoionizing states of the Eu, [17] Ba, [18] and Sm [19] atoms. This is as expected because the profile of autoionizing state reflects the interaction between valence electrons of an atom, especially for the lowest-n member of the autoionizing Rydberg state in this case.…”