On dewetting dynamics of solid films of hydrogen isotopes and its influence on tritium β spectroscopy

The dewetting dynamics of solid films of hydrogen isotopes, quench-condensed on a graphite substrate, was measured at various temperatures below desorption by observing the stray light from the film. A schematic model describing the dewetting process by surface diffusion is presented, which agrees qualitatively with our data. The activation energies of different hydrogen isotopes for surface diffusion were determined. The time constant for dewetting of a quench-condensed T-2 film at the working temperature of 1.86 K of the mainz neutrino mass experiment was extrapolated.