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Title: Oxidation State of 229Th Recoils Implanted into MgF 2 Crystals

Abstract

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, Th n+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 MgF 2 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+:MgF 2 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 nuclearmore » clock.« less

Authors:
 [1]; ORCiD logo [2];  [2]; ORCiD logo [2]; ORCiD logo [2];  [2];  [2]; ORCiD logo [2]
  1. Idaho National Lab. (INL), Idaho Falls, ID (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1504649
Report Number(s):
LA-UR-16-27167
Journal ID: ISSN 2330-0981
Grant/Contract Number:  
89233218CNA000001; AC5206NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Science Journal of Chemistry
Additional Journal Information:
Journal Volume: 6; Journal Issue: 4; Journal ID: ISSN 2330-0981
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 229Th Isomeric State; Nuclear Clock; Optical Spectroscopy; Density Functional Theory; Thorium Doped MgF2 Crystal

Citation Formats

Barker, Beau J., Meyer, Edmund Richard, Schacht, Mike, Collins, Lee A., Wilkerson, Marianne Perry, Ellis, Jason, Martin, Richard L., and Zhao, Xinxin. Oxidation State of 229Th Recoils Implanted into MgF2 Crystals. United States: N. p., 2018. Web. doi:10.11648/j.sjc.20180604.15.
Barker, Beau J., Meyer, Edmund Richard, Schacht, Mike, Collins, Lee A., Wilkerson, Marianne Perry, Ellis, Jason, Martin, Richard L., & Zhao, Xinxin. Oxidation State of 229Th Recoils Implanted into MgF2 Crystals. United States. doi:10.11648/j.sjc.20180604.15.
Barker, Beau J., Meyer, Edmund Richard, Schacht, Mike, Collins, Lee A., Wilkerson, Marianne Perry, Ellis, Jason, Martin, Richard L., and Zhao, Xinxin. Wed . "Oxidation State of 229Th Recoils Implanted into MgF2 Crystals". United States. doi:10.11648/j.sjc.20180604.15. https://www.osti.gov/servlets/purl/1504649.
@article{osti_1504649,
title = {Oxidation State of 229Th Recoils Implanted into MgF2 Crystals},
author = {Barker, Beau J. and Meyer, Edmund Richard and Schacht, Mike and Collins, Lee A. and Wilkerson, Marianne Perry and Ellis, Jason and Martin, Richard L. and Zhao, Xinxin},
abstractNote = {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.},
doi = {10.11648/j.sjc.20180604.15},
journal = {Science Journal of Chemistry},
issn = {2330-0981},
number = 4,
volume = 6,
place = {United States},
year = {2018},
month = {10}
}

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