Optical absorption spectra of ultrathin PTCDA films on gold single crystals: Charge transfer beyond the first monolayer
Optical absorption spectra of ultrathin PTCDA films on gold single crystals: Charge transfer beyond the first monolayer
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DOI：
10.1016/j.orgel.2009.08.005
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发表时间：
2009-12-01
影响因子：
3.2
通讯作者：
Fritz, Torsten
中科院分区：
文献类型：
--
作者：
Forker, Roman;Golnik, Christian;Fritz, Torsten
本文报道了在Au（11 11）和Au（10 0 0）上外延生长的超薄3,4,9,10-苝四羧酸二酐（PTCDA）薄膜的光学吸光度行为。虽然以前在Au（11 11）上的PTCDA被归类为弱相互作用，没有明显的金属-有机电荷转移（CT），但我们提供了在界面上电离PTCDA的明确光学证据。出乎意料的是，PTCDA的充电不仅限于接触层，而且至少延伸到第二层。光谱中的一个新特征被确定为PTCDA阳离子，我们认为第二层单层（部分）带正电。我们认为CT与Au上第一层和第二层PTCDA单层之间的界面偶极子形成有关。(C) 2009 Elsevier B.V.版权所有
We report on the optical absorbance behavior of ultrathin 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) films epitaxially grown on Au(1 1 1) and Au(1 0 0). Although PTCDA on Au(1 1 1) has been classified before as weakly interacting without noticeable metal-organic charge transfer (CT), we present clear optical evidence for ionized PTCDA at the interface. Unexpectedly, the charging of PTCDA is not restricted to the layer of contact, but extends into the second monolayer at least. A new feature in the optical spectra is identified as PTCDA cation, and we reason that the second monolayer is (partly) positively charged. We propose the CT to be related to the interface dipole formation between the first and second PTCDA monolayers on Au. (C) 2009 Elsevier B.V. All rights reserved.