A note on the spin-polarization of hydrogen atoms in a helium–hydrogen gas mixture

Abstract

In a helium–hydrogen mixture at T = 300 K, the polarization degree of hydrogen spins, both electron and nuclear, was determined to be as high as (5 ± 1)%.The role of the main processes giving rise to the formation of spin-polarized H atoms has been discussed. It is shown that an effective transfer of angular momentum from the preliminarily optically oriented He*(23S1) atoms to the H atoms is not due to the direct chemi-dissociation of the H2 molecules by the He* atoms alone, or due to Penning ionization of these molecules followed by the ion-molecular rearrangement reaction H2+ + H2 → H3+ + H alone, but to their summary action. The relative importance of the two mechanisms depends on the rotational temperature and total gas pressure.