The propagation of tritium decay betas and their subsequent emission at the surface of metal tritide films and in particular lithium tritide have been examined theoretically and experimentally. Calculations on the basis of a simple particle balance model have been carried out to determine the relative electron emission at the surface of a variety of binary metal tritides. The results show that a lithium tritide film of effectively infinite thickness would yield the largest electron number and energy flux of the practical binary metal tritides considered. Single scattering Monte Carlo simulations of tritium decay electrons have been performed to determine distributions of the electron energy and of the energy E_n, where E_n is the kinetic energy associated with the normal component of the electron velocity, at the surface of effectively infinite thickness lithium tritide, magnesium tritide and titanium tritide films.

Lithium tritide films of effectively infinite thickness and various tritium to lithium atom ratios have been prepared. The integrated electron flux and the distribution of energy E_n (the latter measured over E_n energies ranging from ~0.05 keV to 7.4 keV) at the surface of lithium tritide film have been measured with a planar retarding potential analyzer. The measured integrated electron flux for electrons of energies exceeding 0.05 keV is 1.1 nA cm⁻², which is twice the value obtained from the Monte Carlo simulation. Underestimation by the Monte Carlo result is attributed to the simulation not accounting for the generation of any secondary electrons. This is evident in the comparison of the measured and computed distributions of energy E_n, where the measured flux is notably greater than the computed result for E_n below about 1.5 keV while for E_n above 1.5 keV the two distributions are in reasonably good agreement. Calculations of the contributions of high energy secondary electrons generated through collision with essentially free electrons and Auger electrons suggest that the observed discrepancy can be accounted for by the presence of impurities in the near surface region of lithium tritide film. The result of a simple experiment strengthens the plausibility of the explanation.