Mui Collin, Han Joseph H, Wang George T, Musgrave Charles B, Bent Stacey F
Department of Chemical Engineering, Stanford University, Stanford, California 94305-5025, USA.
J Am Chem Soc. 2002 Apr 17;124(15):4027-38. doi: 10.1021/ja0171512.
The concept of proton affinity on semiconductor surfaces has been explored through an investigation of the chemistry of amines on the Ge(100)-2 x 1, Si(100)-2 x 1, and C(100)-2 x 1 surfaces. Multiple internal reflection Fourier transform infrared (MIR-FTIR) spectroscopy, temperature programmed desorption (TPD), and density functional theory (DFT) calculations were used in the studies. We find that methylamine, dimethylamine, and trimethylamine undergo molecular chemisorption on the Ge(100)-2 x 1 surface through the formation of Ge-N dative bonds. In contrast, primary and secondary amines react on the Si(100)-2 x 1 surface via N-H dissociation. Since N-H dissociation of amines at semiconductor surfaces mimics a proton-transfer reaction, the difference in chemical reactivities of the Ge(100)-2 x 1 and Si(100)-2 x 1 surfaces toward N-H dissociation can be interpreted as a decrease of proton affinity down a group in the periodic table. The trend in proton affinities of the two surfaces is explained in terms of thermodynamics and kinetics. Solid-state effects on the C(100)-2 x 1 surface and the surface proton affinity concept are discussed based on our theoretical predictions.
通过对锗（100）-2×1、硅（100）-2×1和碳（100）-2×1表面上胺类化学性质的研究，探索了半导体表面质子亲和力的概念。研究中使用了多次内反射傅里叶变换红外（MIR-FTIR）光谱、程序升温脱附（TPD）和密度泛函理论（DFT）计算。我们发现甲胺、二甲胺和三甲胺通过形成锗-氮配位键在锗（100）-2×1表面发生分子化学吸附。相比之下，伯胺和仲胺在硅（100）-2×1表面通过N-H解离进行反应。由于胺类在半导体表面的N-H解离模拟了质子转移反应，锗（100）-2×1和硅（100）-2×1表面对N-H解离的化学反应性差异可解释为元素周期表中同一族质子亲和力的降低。从热力学和动力学角度解释了两个表面质子亲和力的趋势。基于我们的理论预测，讨论了碳（100）-2×1表面的固态效应和表面质子亲和力概念。
