The importance of frontier orbital symmetry in the adsorption of diiodobenzene on MoS2(0001)

Abstract Evidence of a role of frontier orbital symmetry, in the adsorption process of diiodobenzene on MoS2(0001), appears in the huge differences in the rate of adsorption between 1,3-diiodobenzene, 1,2-diiodobenzene and 1,4-diiodobenzene isomers on MoS2. Experiments indicate that the rate of adsorption of 1,3-diiodobenzene on MoS2(0001) is much greater than that of the 1,2-diodobenzene and 1,4-diiodbenzene isomers. As the differences in calculated diiodobenzene isomer-MoS2 system adsorption energies and electron affinities are negligible, frontier orbital symmetry appears to play a significant role in diiodobenzene adsorption on MoS2(0001). The experimental and theory results, in combination, suggest that a rehybridization requirement, forced by frontier orbital symmetry, comes a cost of a reduced sticking coefficient. With the introduction of defects, which lower the adsorption site symmetry at the MoS2(0001) surface, the rate of 1,3-diiodobenzene adsorption on MoS2(0001) decreases, while the rates of 1,2-diodobenzene adsorption significantly increases.