CO在轻微氧化的Mo(100)表面上的吸附和反应

应用HREELS和TDS研究了120K时CO在轻微氧化的Mo(100)上的吸附和脱附状况.120K时,CO在轻微氧化的Mo(100)上存在顶位垂直吸附(ν_CO=2016～2050cm^-1)、四重空位倾斜吸附(ν_CO=1088cm^-1)和通过π键与表面发生作用的倾斜吸附(ν_CO=1600cm^-1).当表面温度升高时,顶位吸附的CO在低覆盖度下发生解离,但在较高覆盖度下,可以同时发生脱附(T_p=319K)和解离;而后两种吸附态在温度升高时只发生解离.CO解离产生的C原子和O原子在930K和1320K时可重新结合成CO脱附.

Adsorption and Reaction of CO on the Slightly Oxidized Mo(100) Surface

The adsorption and desorption of COon the slightly oxidized Mo(100) surface at 120 Kwere studied by HREELSand TDS. It was found that three COmolecular states existed on the slightly oxidized Mo(100) surface at 120 K, namely COterminally bonded on a top sites (v_CO =2016-2050 cm^-1 ), bonded in four-fold hollow sites with a tilted geometry (v_CO =1088 cm^-1 ) and bonded in an inclined manner to a Mo atom through the carbon end and further coordinated to another Mo atom through a π CObond (v_CO =1600 cm^-1 ) respectively. For the terminally bonded CO, heating the surface induced the dissociation at lower coverage. At the higher coverage, however, heating the sample caused the dissociation occurring below 450 Kand desorption( T_p=319 K) simultaneously. For other two COstates, only dissociation could be detected during heating the surface. The chemisorbed carbon and oxygen atoms produced from COdissociation could be recombined to form COto leave the surface at 928 and ~1320 K.