It is determined by experiments that the Kirkendall markers placed at the interface of a diffusion couple, formed by welding a thin plate of metal A to a similar plate of metal B, move with a velocity of 4.5 x 10 ^-12 m/s toward the A component when the composition X _A = 0.38 and the concentration gradient, dn _A /dx, is 2.5 x 10 ² per m. The chemical diffusion coefficient D̃ under these conditions is 3.25 x 10 ^-14 m ² /s. Determine the values of the intrinsic diffusivities of the two components.