Fang Ming, Baldelli Steven
Department of Chemistry, University of Houston, 4800 Calhoun Road, Houston, Texas 77204-5003, United States.
J Phys Chem Lett. 2015 Apr 16;6(8):1454-60. doi: 10.1021/acs.jpclett.5b00215. Epub 2015 Apr 3.
An octadecanethiol (ODT) self-assembled monolayer on microcrystalline copper was investigated by sum frequency generation (SFG) imaging microscopy. The crystal grain and grain boundaries of the copper surface were mapped in the SFG image based on the strong brightness contrast of the SFG signal across the boundary. Local SFG spectra reveal significant difference with each other as well as the average SFG spectra, indicating the heterogeneity of the copper surface resulting from copper grains with distinct crystallographic facets and orientations. It is demonstrated that the SFG signal of crystalline domain areas contains azimuthal anisotropy with respect to the plane of incidence. In addition, the statistical orientation analyses of amplitude ratio of CH3-sym/CH3-asym and corresponding contour maps imply that the orientation of ODT molecules is affected by the underlying copper.
通过和频产生（SFG）成像显微镜研究了微晶铜上的十八烷硫醇（ODT）自组装单分子层。基于SFG信号在边界处的强烈亮度对比，在SFG图像中绘制了铜表面的晶粒和晶界。局部SFG光谱彼此之间以及与平均SFG光谱都存在显著差异，这表明铜表面的异质性是由具有不同晶体学面和取向的铜晶粒导致的。结果表明，晶畴区域的SFG信号相对于入射平面包含方位角各向异性。此外，CH3对称/CH3不对称振幅比的统计取向分析及相应的等高线图表明，ODT分子的取向受底层铜的影响。
