229ThF4 thin films for solid-state nuclear clocks

After nearly 50 years of searching, the vacuum ultraviolet ²²⁹Th nuclear isomeric transition has recently been directly laser excited^1,2 and measured with high spectroscopic precision³. Nuclear clocks based on this transition are expected to be more robust^4,5 than and may outperform6,7 current optical atomic clocks. These clocks also promise sensitive tests for new physics beyond the standard model^5,8–12.