Smith D P, Bryant A, Quate C F, Rabe J P, Gerber C, Swalen J D
Proc Natl Acad Sci U S A. 1987 Feb;84(4):969-72. doi: 10.1073/pnas.84.4.969.
The molecular structure of a fatty acid bilayer has been recorded with a scanning tunneling microscope operating in air. The molecular film, a bilayer of cadmium icosanoate (arachidate), was deposited onto a graphite substrate by the Langmuir-Blodgett technique. The packing of the lipid film was found to be partially ordered. Along one axis of the triclinic unit cell the intermolecular distance varied randomly around a mean of 5.84 A with a SD of 0.24 A. Along the other axis the mean distance was 4.1 A and appeared to vary monotonically over several intermolecular distances, indicating that a superstructure of longer range may exist. The molecular density was one molecular per 19.4 A2. The surprising ability of the scanning tunneling microscope to image the individual molecular chains demonstrates that electrons from the graphite can be transferred along the molecular chains for a distance of 50 A.
利用在空气中工作的扫描隧道显微镜记录了脂肪酸双层的分子结构。通过朗缪尔-布洛杰特技术将分子膜，即二十二酸镉（花生酸）双层，沉积在石墨基底上。发现脂质膜的堆积是部分有序的。在三斜晶胞的一个轴向上，分子间距离围绕5.84埃的平均值随机变化，标准差为0.24埃。在另一个轴向上，平均距离为4.1埃，并且在几个分子间距离上似乎单调变化，这表明可能存在更大范围的超结构。分子密度为每19.4平方埃一个分子。扫描隧道显微镜对单个分子链成像的惊人能力表明，来自石墨的电子可以沿着分子链转移50埃的距离。
