A study of deuterium interaction with diamond (110) single crystal surface by TPD, EELS and LEED

Abstract The present paper describes, for the first time, the desorption of deuterium from a degraded and well-defined microwave (MW) treated Di(110) surface. The interaction of deuterium with the Di(110) surface was studied by thermal programmed desorption (TPD), low energy electron diffraction (LEED), and low energy electron energy loss spectroscopy (EELS). It was found that hydrogen MW plasma treatment yielded (111) faceting on the well-defined Di(110):H surface. Heating the hydrogenated surface at 1100 °C in vacuum resulted in hydrogen desorption. Activated low-coverage deuterium adsorption on the Di(110) surface was performed in situ. From the well-defined surface, deuterium desorbed, yielding a single desorption peak, γ 1 , at ∼960 °C. Due to numerous deuterium adsorption/desorption cycles, the well-defined Di(110) surface was gradually degraded. From the degraded Di(110) surface a broad desorption peak, γ 2 , centered at ∼660 °C, in addition to the γ 1 peak, was detected in the TPD spectrum. It is suggested that the γ 1 peak is associated with C–D bond breaking on the diamond structure. By contrast, it is suggested that the γ 2 peak is connected with desorption from different sites on non-diamond carbon. Desorption from the γ 1 sites was found to obey first-order kinetics. The activation energy and pre-exponential factor of deuterium desorption from γ 1 sites were determined to be 75.5 kcal/mol and 3×10 12  s −1 , respectively. A possible mechanism describing the first-order desorption kinetics is discussed. This discussion includes a comparison with other reports and with our own results on deuterium desorption from the Di(111) and Di(100) surfaces.