An experimental study on the potential energy diagram for hydrogen isotopes on copper surfaces

Rate constants of thermally activated processes for deuterium near a copper surface were experimentally studied. Combining techniques of the deuterium depth profiling near the surface and the permeation measurement, both the areal density of deuterium on the surface and the concentration of deuterium dissolved near the surface were observed simultaneously. Based on the idealized potential energy diagram, the observed data yielded the activation energy for two rate constants; 0.30 eV for the recombination of two atoms and subsequent desorption from the surface and 0.64 eV for the jumping of one atom from the surface to the bulk. From these values, the temperature dependence of the recombination coefficient was estimated.