Adsorption state of 1,4-cyclohexadiene on Si(100)(2X1)

The adsorption state of 1,4-cyclohexadiene on a Si(100)(2x1) surface is stu died using low-energy electron diffraction (LEED) and photoelectron spectro scopy (PES). LEED shows a sharp 2x1 pattern at saturation after the adsorpt ion of 1,4-cyclohexadiene indicating that the Si dimer structure is maintai ned. Judging from the PES results, almost all the dangling bonds react on a dsorption of 1,4-cyclohexadiene, and one of the two pi bonds in 1,4-cyclohe xadiene reacts with the Si dimer. Thus, the molecule adsorbs on a Si(100)(2 x1) dimer one to one with di-sigma bonding, and the ideal saturation covera ge is expected to be 0.5 monolayer. It is concluded that the molecules are anisotropically aligned and the molecular plane is inclined from the surfac e normal. with the remaining ii bond located at the vacuum side.