长链烷烃和醇在石墨表面吸附的扫描隧道显微镜研究

Scanning tunneling microscopy studies of alkane and alkanol adsorbed on graphite

用扫描隧道显微镜 (STM)研究了室温下十八醇 ( 1 C1 8H37OH)和十四烷 (C1 4H30 )在石墨表面的吸附行为 .十八醇在石墨表面自组装形成条状结构 .实验发现了十八醇分子在石墨表面的两种不同的密排方式 ,它们形成并列的不同宽度的条状结构 .还发现 ,由于溶剂 (正十四烷C1 4H30 )的完全蒸发 ,留下的十八醇分子在石墨表面吸附的自组装结构与固液界面中十八醇分子在石墨表面的吸附形成的结构在分子方向、表面分子晶体的晶格常数及条状结构宽度等方面有很大的不同 .此外 ,实验中也发现溶剂十四烷在某种情况下也能在石墨表面吸附形成可供STM观察的有较长时间稳定性的条状周期结构 .实验观察到的十四烷在石墨表面形成的晶体结构与固液界面中观察到的有序结构的晶体结构常数和分子排列方向也是不同的 .根据STM图像 。

The behavior of tetradecane and octadecanol adsorbed on graphite in solid-gas interface is investigated at room temperature by STM. The studies reveal that tetradecane and octadecanol on graphite are self-assembled into a high degree of two-dimensional order, and the lamellar structure, which is similar to that of STM observation in solid-liquid interface, is obtained. But the high-resolution images give striking differences in molecular arrangement, lattice constant and orientation of molecules in one lamella, and we attribute these differences to the solvent effect suggested in previous neutron diffraction studies.