BINDING OF SPIN-POLARIZED HYDROGEN TO THE FREE-SURFACE OF LIQUID-HELIUM

The binding energy of a single H, D, or T atom to the free surface of liquid He4 has been calculated by a variational method. The calculation is of the Feynman-Lekner form, generalized to include the difference between the H-He and He-He interatomic potentials. The results depend on various properties of the pure He4 surface: the density and kinetic energy distribution, and the two body correlation function. These have been obtained partly from data on atomic scattering at the surface, and partly from a theoretical model which emphasizes the asymptotic behavior far above the surface. It is believed that the assumptions about the He4 surface lead to genuine lower limits for the H, D, and T binding energies. The binding of H to the surface is at least 0.6 K, which is large enough to be important for low-temperature experiments on spin-polarized hydrogen. © 1979 The American Physical Society.