Oxidation State of 229Th Recoils Implanted into MgF2 Crystals
Science Journal of Chemistry
Volume 6, Issue 4, August 2018, Pages: 66-76
Received: Aug. 31, 2018; Accepted: Sep. 25, 2018; Published: Oct. 31, 2018
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Beau J. Barker, Idaho National Laboratory, Idaho Falls, USA
Edmund R. Meyer, Los Alamos National Laboratory, Los Alamos, USA
Michael H. Schacht, Los Alamos National Laboratory, Los Alamos, USA
Lee A. Collins, Los Alamos National Laboratory, Los Alamos, USA
Marianne P. Wilkerson, Los Alamos National Laboratory, Los Alamos, USA
Jason K. Ellis, Los Alamos National Laboratory, Los Alamos, USA
Richard L. Martin, Los Alamos National Laboratory, Los Alamos, USA
Xinxin Zhao, Los Alamos National Laboratory, Los Alamos, USA
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A solid-state nuclear clock based on the low-lying isomeric state in 229Th has attracted growing interest. One potential problem for the solid-state nuclear clock approach is the suitability of the doped environment for photon emission of the nuclear isomeric state. Specifically, Thn+ n < 4 ions could open non-radiative decay routes for deexcitation, hindering the photon emission. Here we have used time-resolved photoluminescence (TRPL) and density functional theory (DFT) calculations to characterize MgF2 crystals that have been implanted with 229Th recoils via a-decay from a 233U source with the goal of determining the charge state of the implanted thorium atoms. The DFT calculations predicted Th4+ to be the lowest energy oxidation state with Th3+ the next lowest in the MgF2 crystal environment. The DFT calculations also show Th4+:MgF2 system has a band gap large enough so that the internal electron conversion decay channel is suppressed. Experimentally, we found no evidence for thorium in oxidations state other than +4 using TRPL spectroscopy that has a detection limit for Thn+ n < 4 ions several orders of magnitude smaller than the number of implanted 229Th recoils. This work shows that the solid-state approach is a viable option for a nuclear clock.
229Th Isomeric State, Nuclear Clock, Optical Spectroscopy, Density Functional Theory, Thorium Doped MgF2 Crystal
To cite this article
Beau J. Barker, Edmund R. Meyer, Michael H. Schacht, Lee A. Collins, Marianne P. Wilkerson, Jason K. Ellis, Richard L. Martin, Xinxin Zhao, Oxidation State of 229Th Recoils Implanted into MgF2 Crystals, Science Journal of Chemistry. Vol. 6, No. 4, 2018, pp. 66-76. doi: 10.11648/j.sjc.20180604.15
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