ThF thin films for solid-state nuclear clocks.

After nearly 50 years of searching, the vacuum ultraviolet Th nuclear isomeric transition has recently been directly laser excited and measured with high spectroscopic precision. Nuclear clocks based on this transition are expected to be more robust than and may outperform current optical atomic clocks. These clocks also promise sensitive tests for new physics beyond the standard model.

Laser Excitation of the ^{229}Th Nuclear Isomeric Transition in a Solid-State Host.

LiSrAlF_{6} crystals doped with ^{229}Th are used in a laser-based search for the nuclear isomeric transition. Two spectroscopic features near the nuclear transition energy are observed. The first is a broad excitation feature that produces redshifted fluorescence that decays with a timescale of a few seconds.