Optical Excitation and Trapping of Kr 81

We have realized optical excitation, trapping, and detection of the radioisotope $^{81}\mathrm{Kr}$ with an isotopic abundance of 0.9 ppt. The 124 nm light needed for the production of metastable atoms is generated by a resonant discharge lamp. Photon transport through the optically thick krypton gas inside the lamp is simulated and optimized to enhance both brightness and resonance. We achieve a state-of-the-art $^{81}\mathrm{Kr}$ loading rate of $1800\text{ }\text{ }\mathrm{atoms}/\mathrm{h}$, which can be further scaled up by adding more lamps. The all-optical approach overcomes the limitations on precision and sample size of radiokrypton dating, enabling new applications in the earth sciences, particularly for dating of polar ice cores.