Surface phonons, electronic structure and chemical reactivity of diamond (100)(2 x 1) surface

Surface phonons, electronic structure and chemical reactivity of the diamon d (100)(2 x 1) surface have been studied using electron energy loss spectro scopy (EELS), thermal desorption spectroscopy (TDS) and low-energy electron diffraction (LEED). Vibrational losses are observed at similar to 80, 92, 123, 135, 147 and 165 meV for a clean C(100)(2 x 1) surface. The 92 meV los s is assigned to the in-phase bouncing mode of the surface dimers. The orig ins of the other losses are discussed. Electronic transition is observed at 3.5 eV which is associated with the interband transition between the pi an d pi* surface states. The chemical reactivity of the C(100)(2 x 1) surface towards several gases, H, H-2, O, O-2, CO, N2O and C2H2, has been investiga ted at 90 and 300 K. The chemical reactivity of the C(100)(2 x 1) surface t owards these gases is compared with that of the Si(100)(2 x 1) surface, and the origin of the difference in the reactivity is discussed.