Thermal compression of atomic hydrogen on helium surface

Abstract

We describe experiments with spin-polarized atomic hydrogen gas adsorbed on liquid ${}^4$He surface. The surface gas density is increased locally by thermal compression up to $5.5\times 10^{12}$ cm${}^{-2}$ at 110 mK. This corresponds to the onset of quantum degeneracy with the thermal de-Broglie wavelength being 1.5 times larger than the mean interatomic spacing. The atoms were detected directly with a 129 GHz electron-spin resonance spectrometer probing both the surface and the bulk gas. This, and the simultaneous measurement of the recombination power, allowed us to make accurate studies of the adsorption isotherm and the heat removal from the adsorbed hydrogen gas. From the data, we estimate the thermal contact between 2D hydrogen gas and phonons of the helium film. We analyze the limitations of the thermal compression method and the possibility to reach the superfluid transition in 2D hydrogen gas.

20 pages, 11 figures

References in corpus (6)

• Berezinskii-Kosterlitz-Thouless Crossover in a Trapped Atomic Gas
• Bose-Einstein condensation in quasi2D trapped gases
• Two-Dimensional Weakly Interacting Bose Gas in the Fluctuation Region
• Low-dimensional Bose gases
• Adsorption and two-body recombination of atomic hydrogen on ${}^3$He-${}^4$He mixture films
• Thermal compression of two-dimensional atomic hydrogen to quantum degeneracy

Cited by in corpus (2)

• Hyperfine frequency shift in two-dimensional atomic hydrogen
• Spin-polarized hydrogen adsorbed on the surface of superfluid 4He