Production of spin-polarized molecular beams via microwave or infrared rotational excitation

We propose schemes to produce highly nuclear-spin polarized small molecules in an intense and cold molecular beam via microwave or infrared rotational excitation, followed by hyperfine-induced quantum beats. Repumping schemes can be used to achieve polarization above 90% in cases where single-pumping schemes are insufficient. We discuss the possibility of high production rates which allow applications including nuclear-magnetic-resonance signal enhancement, and spin-polarized nuclear fusion, where polarized nuclei are known to enhance D-T and D- 3 He fusion cross sections by 50%. • Schemes proposed to produce spin-polarized molecular beams with IR/MW excitation. • Estimated production rates may exceed 1 0 21 s − 1 from intense IR/MW sources. • Spin-polarized molecules can enhance NMR/ESR signals or nuclear fusion cross sections.