Scanning tunneling microscopy and scanning tunneling spectroscopy studies of planar and nonplanar naphthalocyanines on graphite (0001).: Part 1:: Effect of nonplanarity on the adlayer structure and voltage-induced flipping of nonplanar tin-naphthalocyanine
Scanning tunneling microscopy and scanning tunneling spectroscopy studies of planar and nonplanar naphthalocyanines on graphite (0001).: Part 1:: Effect of nonplanarity on the adlayer structure and voltage-induced flipping of nonplanar tin-naphthalocyanine
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DOI：
10.1021/jp055533e
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发表时间：
2006-03-30
影响因子：
3.3
通讯作者：
Hietschold, M
中科院分区：
文献类型：
--
作者：
Gopakumar, TG;Müller, F;Hietschold, M
利用超高真空条件下的变温扫描隧道显微镜，研究了低样品温度（50 K）下，平面分子无碱萘菁（Nc）和非平面分子锡萘菁（SnNc）在新切割的高取向热解石墨（HOPG）表面的吸附。平面分子形成大面积无缺陷有序单层，分子堆积密度高，而非平面分子表现出不同的吸附相，分子堆积密度较低。SnNc层遵循与石墨衬底相同的几何形状，形成纯吸附相，所有分子都呈Sn2+向上或Sn2+向下的几何形状。此外，在Sn2+向下的另一相中还观察到一维选择性。多层膜在每种情况下表现出完全不同的吸附方式。Nc分子表现为柱状堆积，SnNc分子表现为非柱状堆积。值得注意的是，已经观察到单层中非平面锡-萘菁的电压诱导翻转，这可能应用于单分子信息存储。
The adsorption of base-free naphthalocyanine (Nc), a planar molecule, and tin-naphthalocyanine (SnNc), a nonplanar molecule, on a freshly cleaved highly oriented pyrolytic graphite (HOPG) surface at low sample temperature (50 K) has been studied using a variable-temperature scanning tunneling microscope in ultrahigh vacuum conditions. The planar molecules form large areas of defect-free ordered monolayer with high molecular packing density while the nonplanar molecules show different phases of adsorption with lower molecular packing density. The SnNc adlayers follow the same geometry as the graphite substrate and form pure phases of adsorption with either all molecules in a Sn2+ up or Sn2+ down geometry. Moreover, a one-dimensional selectivity is observed in still another phase of Sn2+ down geometry. Multilayers show a completely different kind of adsorption in each case. Nc molecules show columnar pi-stacking whereas the SnNc molecules exhibit noncolumnar stacking. Distinctly, a voltage-induced flipping of nonplanar tin-naphthalocyanine in the monolayer has been observed which can possibly be applied to single-molecular information storage.