Zero-Field Hyperfine Resonance of Atomic Hydrogen for 0.18<~T<~1 K: The Binding Energy of H on Liquid He4

Magnetic-resonance studies of the 1420-MHz transition in atomic hydrogen have yielded an accurate value for the binding energy of atomic H on liquid He4. A value of 0.93±0.05 K is derived from two independent determinations of the surface binding: one from the shift in the hyperfine frequency, and the other from the recombination rate. The rate constant for H-H recombination in zero field and the hyperfine frequency of an H atom in the bound surface state have also been determined.