Lustemberg P G, Martiarena M L, Martínez A E, Busnengo H F
Centro Atómico Bariloche, and Instituto Balseiro, Av Bustillos 9500, 8400 S. C. de Bariloche, Argentina.
Langmuir. 2008 Apr 1;24(7):3274-9. doi: 10.1021/la703306t. Epub 2008 Feb 23.
Density functional theory was used to investigate the reaction pathways for HSCH(3) adsorption on Au(111) at low coverage. A molecular adsorbed state was found with the S atom bond on Top sites (E approximately -0.38 eV) and molecular adsorption is nonactivated. The H-SCH(3) dissociation process is energetically less favorable and becomes slightly exothermic only when surface relaxation is considered (DeltaE approximately -0.2 eV). All the reaction pathways present a sizable activation energy barrier, with the lowest being approximately 0.52 eV (0.41 eV taking into account slab relaxation). In the corresponding saddle point of the potential energy surface, the S atom of the methylthiolate molecule is placed on Top sites and the H near a Bridge site. The high barrier obtained explains the complete absence of reactive methanethiol dissociation found in recent experiments.
采用密度泛函理论研究了低覆盖度下HSCH(3)在Au(111)上的吸附反应路径。发现了一种分子吸附态，其中S原子键合在顶位（能量约为-0.38 eV），分子吸附是非活化的。H-SCH(3)解离过程在能量上不太有利，只有在考虑表面弛豫时才会略微放热（ΔE约为-0.2 eV）。所有反应路径都存在相当大的活化能垒，最低约为0.52 eV（考虑平板弛豫时为0.41 eV）。在势能面的相应鞍点处，甲硫醇盐分子的S原子位于顶位，H靠近桥位。得到的高势垒解释了最近实验中未发现反应性甲硫醇解离的原因。
