Generation of nuclear-spin-polarized protons by resonant ionization of hydrogen atoms

An atomic beam of H atoms was crossed by a pulsed beam of narrow bandwidth (Δν∼700 MHz) circularly polarized tunable vuv laser radiation at λ=121.6 nm. The atoms were excited into a single magnetic substate in the 2p ${\mathrm{}}^2$ $P_{1/2}$ level and thus polarized. This polarization is transferred via hyperfine interaction to the nucleus. A second tunable uv laser served to ionize these atoms, thereby producing nuclear-spin-polarized protons with, theoretically, 100% degree of polarization. By changing the helicity of the circularly polarized vuv laser with a quarter-wave plate, the polarization direction of the protons is changed.