Identifying Molecular Orbital Energies by Distance-Dependent Transition Voltage Spectroscopy

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• 作者：M. Christina Lennartz ; Nicolae Atodiresei ; Vasile Caciuc ; Silvia Kartha虉user
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：August 4, 2011
• 年：2011
• 卷：115
• 期：30
• 页码：15025-15030
• 全文大小：825K
• 年卷期：v.115,no.30(August 4, 2011)
• ISSN：1932-7455

文摘

Besides current鈥搗oltage spectroscopy, also transition voltage spectroscopy (TVS) becomes an interesting tool to investigate the energetic position of the molecular orbitals involved in the tunneling process. We used scanning tunneling spectroscopy to perform both spectroscopy techniques as a function of the tip鈥搒ubstrate distance. Employing our model system, benzoic acid on a Cu(110) surface, we could observe a step in the transition voltage using distance-dependent TVS. Combining the spectroscopic results with density functional theory based calculations, it was possible to identify the molecular orbitals responsible for charge transport. Moreover, it was found that different molecular orbitals are responsible for charge transport if varying STM tip鈥搒ubstrate distances are examined.