Electronic Structure of Atomically Precise Graphene Nanoribbons

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• 作者：Pascal Ruffieux ; Jinming Cai ; Nicholas C. Plumb ; Luc Patthey ; Deborah Prezzi ; Andrea Ferretti ; Elisa Molinari ; Xinliang Feng ; Klaus M眉llen ; Carlo A. Pignedoli ; Roman Fasel
• 刊名：ACS Nano
• 出版年：2012
• 出版时间：August 28, 2012
• 年：2012
• 卷：6
• 期：8
• 页码：6930-6935
• 全文大小：350K
• 年卷期：v.6,no.8(August 28, 2012)
• ISSN：1936-086X

文摘

Some of the most intriguing properties of graphene are predicted for specifically designed nanostructures such as nanoribbons. Functionalities far beyond those known from extended graphene systems include electronic band gap variations related to quantum confinement and edge effects, as well as localized spin-polarized edge states for specific edge geometries. The inability to produce graphene nanostructures with the needed precision, however, has so far hampered the verification of the predicted electronic properties. Here, we report on the electronic band gap and dispersion of the occupied electronic bands of atomically precise graphene nanoribbons fabricated via on-surface synthesis. Angle-resolved photoelectron spectroscopy and scanning tunneling spectroscopy data from armchair graphene nanoribbons of width N = 7 supported on Au(111) reveal a band gap of 2.3 eV, an effective mass of 0.21 m₀ at the top of the valence band, and an energy-dependent charge carrier velocity reaching 8.2 脳 10⁵ m/s in the linear part of the valence band. These results are in quantitative agreement with theoretical predictions that include image charge corrections accounting for screening by the metal substrate and confirm the importance of electron鈥揺lectron interactions in graphene nanoribbons.

Keywords:

graphene nanoribbon; electronic structure; effective mass; charge carrier velocity; scanning tunneling spectroscopy; photoelectron spectroscopy; image charge corrections; beyond DFT