Ultrahigh-density spin-polarized H and D observed via magnetization quantum beats

Abstract

We measure nuclear and electron spin-polarized H and D densities of at least 10${}^{19}c{m}^{-3}$ with $\sim$10 ns lifetimes, from the photodissociation of HBr and DI with circularly-polarized UV light pulses. This density is $\sim$6 orders of magnitude higher than that produced by conventional continuous-production methods, and, surprisingly, at least 100 times higher than expected densities for this photodissociation method. We observe the hyperfine quantum beating of the H and D magnetization with a pick-up coil, i.e., the respective 0.7 and 3 ns periodic transfer of polarization from the electrons to the nuclei and back. The $10^{19}\mathrm{c}{\mathrm{m}}^{-3}$ spin-polarized H and D density is sufficient for laser-driven ion acceleration of spin polarized electrons, protons, or deuterons, the preparation of nuclear-spin-polarized molecules, and for the demonstration of spin-polarized D-T or D-${}^3\mathrm{He}$ laser fusion, for which a reactivity enhancement of $\sim 50\%$ is expected.