Keele, Julie A.Lundeen, S. R.Fehrenbach, C. W.2023-12-072023-12-072011-06-14https://hdl.handle.net/2097/43838High-resolution studies of the fine-structure pattern in high-L n = 37 levels of Th3+ have been carried out using radio-frequency (rf) spectroscopy detected with resonant excitation Stark ionization spectroscopy (RESIS). Intervals separating L = 9 to L = 15 levels have been measured, and the results analyzed with the long-range effective potential model. The dipole polarizability of Th4+is determined to be αD = 7.720(7) a.u. The quadrupole polarizability is found to be 21.5(3.9) a.u. Both measurements represent significant tests of a priori theoretical descriptions of this highly relativistic ion.© American Physical Society (APS). This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).http://rightsstatements.org/vocab/InC/1.0/https://web.archive.org/web/20181120135245/https://journals.aps.org/copyrightFAQ.htmlText