Resolving intramolecular-distortion changes induced by the partial fluorination of pentacene adsorbed on Cu(111)
Resolving intramolecular-distortion changes induced by the partial fluorination of pentacene adsorbed on Cu(111)
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DOI：
10.1103/physrevmaterials.2.044002
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发表时间：
2018-04-04
影响因子：
3.4
通讯作者：
Schreiber, Frank
中科院分区：
文献类型：
--
作者：
Franco-Canellas, Antoni;Wang, Qi;Schreiber, Frank
本文对部分氟化并五苯（PEN）化合物2，3，9，10-四氟并五苯（F4 PEN）吸附在Cu（111）上的分子弯曲进行了实验定量。利用X射线驻波（XSW）技术直接测量了三个不等价碳位、氟原子的吸附距离以及总碳和骨架碳的平均吸附距离。碳核内不同位点的精确定位使我们能够解决两种吸附行为，即主链和底物之间的PEN样强耦合，以及涉及氟化短分子边缘的排斥相互作用，其在中心苯环上方0.91 +/- 0.09埃。这一发现进一步支持了额外的电子和平面结构的测量，从而表明，选择性的PEN分子的双折射只有一个局部构象的影响，它是不足以修改其界面特性。然而，在多层制度中，薄膜的电子和生长特性完全不同于PEN及其全氟衍生物。
We experimentally quantify the molecular bending of a partially fluorinated pentacene (PEN) compound, namely 2,3,9,10-tetrafluoropentacene (F4PEN), adsorbed on Cu(111). By means of the x-ray standing wave (XSW) technique, we directly measure the adsorption distance of three inequivalent carbon sites, the fluorine atoms as well as the total and backbone carbon average adsorption distances. The precise positioning of different sites within the carbon core allows us to resolve two adsorption behaviors, namely a PEN-like strong coupling between the backbone and the substrate, and a repulsive interaction involving the fluorinated short molecular edges, which are 0.91 +/- 0.09 angstrom above the central benzene ring. This finding is further supported by additional electronic and in-plane-structure measurements, thus showing that the selective fluorination of a PEN molecule has only a local conformational effect and it is not sufficient to modify its interface properties. Yet, in the multilayer regime, the electronic and growth properties of the film differ completely from those of PEN and its perfluorinated derivative.