Adsorption-Induced Intramolecular Dipole: Correlating Molecular Conformation and Interface Electronic Structure

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• 作者：Norbert Koch ; Alexander Gerlach ; Steffen Duhm ; Hendrik Glowatzki ; Georg Heimel ; Antje Vollmer ; Yoichi Sakamoto ; Toshiyasu Suzuki ; Jö ; rg Zegenhagen ; Jü ; rgen P. Rabe ; Frank Schreiber
• 刊名：Journal of the American Chemical Society
• 出版年：2008
• 出版时间：June 11, 2008
• 年：2008
• 卷：130
• 期：23
• 页码：7300 - 7304
• 全文大小：1132K
• 年卷期：v.130,no.23(June 11, 2008)
• ISSN：1520-5126

文摘

The interfaces formed between pentacene (PEN) and perfluoropentacene (PFP) molecules and Cu(111) were studied using photoelectron spectroscopy, X-ray standing wave (XSW), and scanning tunneling microscopy measurements, in conjunction with theoretical modeling. The average carbon bonding distances for PEN and PFP differ strongly, that is, 2.34 Å for PEN versus 2.98 Å for PFP. An adsorption-induced nonplanar conformation of PFP is suggested by XSW (F atoms 0.1 Å above the carbon plane), which causes an intramolecular dipole of ~0.5 D. These observations explain why the hole injection barriers at both molecule/metal interfaces are comparable (1.10 eV for PEN and 1.35 eV for PFP) whereas the molecular ionization energies differ significantly (5.00 eV for PEN and 5.85 eV for PFP). Our results show that the hypothesis of charge injection barrier tuning at organic/metal interfaces by adjusting the ionization energy of molecules is not always readily applicable.