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Properties of Fr-like Th{sup 3+} from spectroscopy of high-L Rydberg levels of Th{sup 2+}

Journal Article · · Physical Review. A
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  1. Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States)
Binding energies of high-L Rydberg states (L{>=} 7) of Th{sup 2+} with n = 27-29 were studied using the resonant excitation Stark ionization spectroscopy (RESIS) method. The core of the Th{sup 2+} Rydberg ion is the Fr-like ion Th{sup 3+} whose ground state is a 5 {sup 2}F{sub 5/2} level. The large-core angular momentum results in a complex Rydberg fine-structure pattern consisting of six levels for each value of L that is only partially resolved in the RESIS excitation spectrum. The pattern is further complicated, especially for the relatively-low-L levels, by strong nonadiabatic effects due to the low-lying 6d levels. Analysis of the observed RESIS spectra leads to determination of five properties of the Th{sup 3+} ion: its electric quadrupole moment Q = 0.54(4); its adiabatic scalar and tensor dipole polarizabilities {alpha}{sub d,0} = 15.42(17) and {alpha}{sub d,2} = -3.6(1.3); and the dipole matrix elements connecting the ground 5 {sup 2}F{sub 5/2} level to the low-lying 6 {sup 2}D{sub 3/2} and 6 {sup 2}D{sub 5/2} levels, |<5 {sup 2}F{sub 5/2}||D||6{sup 2}D{sub 3/2}>|=1.435(10) and |<5{sup 2}F{sub 5/2}||D||6{sup 2}D{sub 5/2}>|=0.414(24). All are in atomic units. These are compared with theoretical calculations.
OSTI ID:
21550090
Journal Information:
Physical Review. A, Journal Name: Physical Review. A Journal Issue: 6 Vol. 83; ISSN 1050-2947; ISSN PLRAAN
Country of Publication:
United States
Language:
English