@ARTICLE{,
  author = {Elwell, Ricky and Terhune, James E. S. and Schneider, Christian and Morgan, Harry W. T. and Tran Tan, Hoang Bao and Perera, Udeshika C. and Rehn, Daniel A. and Alfonso, Marisa C. and von der Wense, Lars and Seiferle, Benedict and Scharl, Kevin and Thirolf, Peter G. and Derevianko, Andrei and Hudson, Eric R.},
  title = {\textsuperscript{229}{Th} Nuclear Spectroscopy in an Opaque Material: Laser-Based Conversion Electron {M}\"{o}ssbauer Spectroscopy of \textsuperscript{229}{Th}{O}$_2$},
  journal = {arXiv},
  year = {2025},
  volume = {2506.03018v1},
  pages = {1--18},
  month = {jun},
  url = {https://arxiv.org/abs/2506.03018v1},
  doi = {10.48550/arXiv.2506.03018},
  abstract = {Here, we report the first demonstration of laser-induced conversion electron M\"{o}ssbauer spectroscopy of the \textsuperscript{229}Th nuclear isomeric state, which provides the ability to probe the nuclear transition in a material that is opaque to light resonant with the nuclear transition. Specifically, we excite the nuclear transition in a thin ThO$_2$ sample whose band gap ($\sim \unit[6]{eV}$) is considerably smaller than the nuclear isomeric state energy ($\unit[8.4]{eV}$). As a result, the excited nucleus can quickly decay by internal conversion, resulting in the ejection of electrons from the surface. By collecting these conversion electrons, nuclear spectroscopy can be recorded. Unlike fluorescence spectroscopy, this technique is compatible with materials whose work function is less than the nuclear transition energy, opening a wider class of systems to study. Further, because ThO$_2$ can be made from spinless isotopes and the internal conversion decay process reduces the isomeric state lifetime to only $\sim \unit[10]{\textmicro s}$, allowing $\sim 10^8$ relative reduction in clock interrogation time, a conversion-electron-based nuclear clock could lead to a $\sim 10^4$ reduction in clock instability.}
}