Cao X, Hamers R J
Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.
J Am Chem Soc. 2001 Nov 7;123(44):10988-96. doi: 10.1021/ja0100322.
The bonding of the trimethylamine (TMA) and dimethylamine (DMA) with crystalline silicon surfaces has been investigated using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy, and density-functional computational methods. XPS spectra show that TMA forms stable dative-bonded adducts on both Si(001) and Si(111) surfaces that are characterized by very high N(1s) binding energies of 402.2 eV on Si(001) and 402.4 eV on Si(111). The highly ionic nature of these adducts is further evidenced by comparison with other charge-transfer complexes and through computational chemistry studies. The ability to form these highly ionic charge-transfer complexes between TMA and silicon surfaces stems from the ability to delocalize the donated electron density between different types of chemically distinct atoms within the surface unit cells. Corresponding studies of DMA on Si(001) show only dissociative adsorption via cleavage of the N-H bond. These results show that the unique geometric structures present on silicon surfaces permit silicon atoms to act as excellent electron acceptors.
利用X射线光电子能谱（XPS）、傅里叶变换红外光谱以及密度泛函计算方法，对三甲胺（TMA）和二甲胺（DMA）与晶体硅表面的键合情况进行了研究。XPS光谱表明，TMA在Si(001)和Si(111)表面均形成稳定的配位键加合物，其特征是在Si(001)表面N(1s)结合能非常高，为402.2 eV，在Si(111)表面为402.4 eV。与其他电荷转移络合物的比较以及通过计算化学研究进一步证明了这些加合物具有高度离子性。TMA与硅表面之间形成这些高度离子性电荷转移络合物的能力源于能够在表面晶胞内不同类型化学性质不同的原子之间离域所捐赠的电子密度。对Si(001)上DMA的相应研究表明，其仅通过N-H键的断裂发生解离吸附。这些结果表明，硅表面存在的独特几何结构使硅原子能够作为优异的电子受体。
