Recombination of spin polarized atomic hydrogen adsorbed on a dilute 3He-4He mixture

Abstract

We have been searching for two-dimensional (2-D) superfluidity of spin-polarized atomic hydrogen (H↓) adsorbed on liquid helium surface. We have investigated H↓ adsorbed on 3 He- 4 He mixtures instead of pure 4 He because the thermal coupling of H↓ to the mixtures is stronger than 4 He, ESR at 129 GHz was carried out to detect H↓ at 4.5 T by using the Fabri-Perot confocal cavity with the cold spot located at the confocal point and thus the 2-D H↓ signal was effectively detected. We investigated the two-body bulk and surface recombination processes of H↓ on a 3 % 3 He 3 He- 4 He mixture film. From the analysis of the surface recombination process, we found the adsorption energy of H↓ was a 0.6 K for the mixture film in the temperature range between 120 mK and 250 mK, greater than the 0.3-0.4 K found previously for pure 3 He and a 67 % 3 He 3 He- 4 He mixture.