Corrugation reversal in scanning tunneling microscope images of organic molecules
Corrugation reversal in scanning tunneling microscope images of organic molecules
复制标题
有机分子扫描隧道显微镜图像中的波纹反转
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
E. Umbach
中科院分区：
文献类型：
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作者：
M. Böhringer;W. Schneider;R. Berndt;K. Glöckler;M. Sokolowski;E. Umbach
用扫描隧道显微镜（STM）研究了295和50 K下苝四甲酸二酐在Ag（110）表面的亚单层覆盖。这些分子形成高度有序的菱形岛，在295 K时与扩散在衬底平台上的分子共存。在50 K的分子岛出现1.4 AA{}高于在STM图像中的Ag衬底，独立的隧道电压和电流。在295 K时，仅在高隧穿电阻下观察到该表观高度。电阻的降低减小了高度差，直到最后岛和周围衬底之间的对比度反转。同时，岛内的空位没有显示对比度反转。我们解释的对比度反转的尖端顶点以下的捕获分子。
Submonolayer coverages of perylene-tetracarboxylic-dianhydride on Ag(110) were investigated with scanning tunneling microscopy (STM) at 295 and 50 K. The molecules form highly ordered rhombic islands which at 295 K coexist with molecules diffusing on the substrate terraces. At 50 K the molecular islands appear 1.4 AA{} higher than the Ag substrate in STM images, independent of the tunneling voltages and currents. At 295 K this apparent height is observed only at high tunneling resistances. Lowering of the resistance decreases the height difference until finally the contrast between islands and the surrounding substrate is reversed. At the same time, vacancies within islands show no contrast reversal. We explain the contrast reversal by trapping of molecules below the tip apex.