Reactions of chlorine with liquid metals. 3. Bismuth

The reaction of molecular chlorine with solid and liquid bismuth was studied by modulated molecular beam-mass spectrometric methods over the temperature range 400-800 K and equivalent chlorine pressures of 5 x 10/sup -6/-2 x 10/sup -4/ torr. The sole reaction product with solid Bi(0001) was BiCl/sub 3/. This species disappeared at the melting point. The molecular beam data collected on the trichloride product exhibited nonlinearity and evidence of both branched and series processes in the mechanism. These results, in conjunction with data obtained in a prior investigation of the system by thermal desorption spectroscopy, permitted development of a model of the reaction on the surface of the solid. With liquid bismuth, only BiCl was detected as reaction product. Its reaction probability increased with temperature, most likely because of a corresponding increase in the chlorine sticking probability. The 45/sup 0/ phase lag exhibited by this species indicated that the kinetics were dominated by solution and diffusion of chlorine in the bulk liquid bismuth. 15 references, 9 figures, 1 table.