Properties of Th4+ and Th3+ from rf spectroscopy of high-L thorium Rydberg ions
Date
2013
Authors
Keele, Julie Adel, author
Lundeen, Stephen R., advisor
Krueger, David A., committee member
Journal Title
Journal ISSN
Volume Title
Abstract
Several properties of radon-like Th4+ and francium-like Th3+ were determined from measurements of high-L Rydberg fine structure in Th3+ and Th2+ ions. The measurements were carried out using the resonant excitation Stark ionization spectroscopy (RESIS) technique to detect rf transitions between levels in the same n. The measured Rydberg fine structures were then fit to an effective potential model, and the properties of the ions were extracted. Properties of the 1S0 ground state of Th4+ extracted from the measurements of the n=37 Th3+ Rydberg fine structure were the scalar dipole polarizability, αD,0=7.702(6)a.u. and the scalar quadrupole polarizability, αQ,0=29.1(1.6)a.u.. The Th2+ Rydberg fine structure is much more complex since the ground state of Th3+ is a 2F5/2, and the presence of low-lying excited states cause non-adiabatic effects in the fine structure which are not well described by the effective potential. To extract the properties, non-adiabatic corrections had to be calculated. The properties of Th3+ extracted were the permanent quadrupole moment, Q=0.5931(14)a.u., the scalar and tensor dipole polarizabilities, αD,0=15.224(33)a.u. and αD,2=-5.30(11)a.u., the permanent hexadecapole moment, Π=-0.69(28)a.u., and the reduced dipole and octupole matrix elements coupling the ground state to the 6d 2D3/2 state, |<g2F5/2
M[1]
6d2D3/2>|=1.436(2)a.u. and |<g2F5/2
M[3]
6d2D3/2>|=3.3(1.1)a.u..
M[1]
6d2D3/2>|=1.436(2)a.u. and |<g2F5/2
M[3]
6d2D3/2>|=3.3(1.1)a.u..