Isotope effect in electron scattering by H or D in palladium

Electron scattering by interstitial hydrogen or deuterium in palladium is investigated by means of measurements of de Haas-van Alphen Dingle temperatures, T D , and electrical resistivity, rho . For Fermi-surface orbits with a strong d character dT D /dx (x is the number of interstitial atoms per Pd atom) is approximately twice as large in PdD x as in PdH x . For electrons on the large Gamma -centred Fermi-surface sheet, however, dT D /dx=750K for both H and D. This value is much smaller than values predicted by average-t-matrix calculations. The experimental value for dT D /dx is, however, confirmed by electrical resistivity measurements on homogeneous alpha -PdH x and alpha -PdD x samples prepared by rapidly cooling down the samples from the hydrogen (deuterium) loading temperature (typically 600K) to helium temperature.