Stabilization of high-density atomic hydrogen inH2films atT<0.5 K

Abstract

The stabilization of high densities of atomic hydrogen $(2\ifmmode\times\else\texttimes\fi{}{10}^{19}\text{ }{\text{cm}}^{\ensuremath{-}3})$ embedded in solid ${\text{H}}_{2}$ films has been achieved by employing a method for producing the samples involving a direct dissociation of ${\text{H}}_{2}$ molecules by a cold plasma discharge in the sample cell at temperatures below 0.5 K. High stabilities against recombination were obtained. We observed density-dependent shifts and widths of the electron spin resonance lines resulting from the dipolar interactions between like and unlike spins. We discuss the possibilities for further increasing the H density and studying possible supersolid behavior.