Separating isotopes via surface diffraction

Isotope separation methods are key to numerous scientific and industrial processes. Nuclear power plants and weapons, for example, require fuels enriched in a select isotope. And isotopically pure or enriched samples are used in scientific research and medical procedures. Isotopes can be separated via fractional distillation, gaseous diffusion, and centrifugation. The process can also be driven by chemical, magnetic, and electrostatic methods. But these techniques are often energy intensive and require many sequential separation steps. Kevin J. Nihill, Jacob D. Graham, and Steven J. Sibener of the University of Chicago have come up with a potentially simpler method based on surface diffraction. The team reports that when a beam of neon strikes a methyl-capped silicon crystal, a portion of the beam diffracts, scattering ²⁰Ne and ²²Ne isotopes into beams that emerge at slightly different angles (Phys. Rev. Lett. 2017, DOI: 10.1103/PhysRevLett.119.176001). A single pass causes ²²Ne, the less abundant isotope, to be enriched by a factor of 3.5. A higher degree of separation can be achieved by using additional diffraction steps or by exploiting mass-based differences in the isotopes’ velocities, the team suggests.