Maass Friedrich, Ajdari Mohsen, Kabeer Fairoja Cheenicode, Vogtland Maximilian, Tkatchenko Alexandre, Tegeder Petra
Ruprecht-Karls-Universität Heidelberg , Physikalisch-Chemisches Institut , Im Neuenheimer Feld 253 , 69120 Heidelberg , Germany.
Fritz Haber Institute of the Max Planck Society , Faradayweg 4-6 , 14195 Berlin , Germany.
J Phys Chem Lett. 2019 Mar 7;10(5):1000-1004. doi: 10.1021/acs.jpclett.9b00265. Epub 2019 Feb 19.
Adsorption energies of chemisorbed molecules on inorganic solids usually scale linearly with molecular size and are well described by additive scaling laws. However, much less is known about scaling laws for physisorbed molecules. Our temperature-programmed desorption experiments demonstrate that the adsorption energy of acenes (benzene to pentacene) on the Au(111) surface in the limit of low coverage is highly nonadditive with respect to the molecular size. For pentacene, the deviation from an additive scaling of the adsorption energy amounts to as much as 0.7 eV. Our first-principles calculations explain the observed nonadditive behavior in terms of anisotropy of molecular polarization stemming from many-body electronic correlations. The observed nonadditivity of the adsorption energy has implications for surface-mediated intermolecular interactions and the ensuing on-surface self-assembly. Thus, future coverage-dependent studies should aim to gain insights into the impact of these complex interactions on the self-assembly of π-conjugated organic molecules on metal surfaces.
化学吸附分子在无机固体上的吸附能通常与分子大小呈线性比例关系，并且可以通过加和比例定律很好地描述。然而，对于物理吸附分子的比例定律却知之甚少。我们的程序升温脱附实验表明，在低覆盖度极限下，蒽类（从苯到并五苯）在Au(111)表面的吸附能相对于分子大小具有高度的非加和性。对于并五苯，吸附能与加和比例的偏差高达0.7电子伏特。我们的第一性原理计算从多体电子关联产生的分子极化各向异性角度解释了观察到的非加和行为。吸附能的非加和性对表面介导的分子间相互作用以及随后的表面自组装有影响。因此，未来与覆盖度相关的研究应旨在深入了解这些复杂相互作用对金属表面π共轭有机分子自组装的影响。
