Direct visualization of diffuse unoccupied molecular orbitals at a rubrene/graphite interface

Yamada, Takashi; Kinoshita, Mariko; Araragi, Kento; Watanabe, Yu; Ueba, Takahiro; Kato, Hiroyuki; Munakata, Toshiaki

doi:10.1039/c8cp01796d

Cited by 8 publications

(2 citation statements)

References 47 publications

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“…Here, the substrate-molecule interactions play an especially important role in terms of the spatial overlap of the wave functions. In this study, we focus on the unoccupied states and discuss the impact of the surface states-mediated hybridization with a molecular orbital [4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Hybridization of an unoccupied molecular orbital with an image potential state at a lead phthalocyanine/graphite interface

Yamada

Kawakita

Okui

et al. 2018

J. Phys.: Condens. Matter

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The interaction of a molecular orbital with a surface state is important to understand the spatial distribution of the wave function at the molecule/substrate interface. In this study, we focus on hybridization of an unoccupied state of lead phthalocyanine (PbPc) with the image potential state (IPS) on a graphite surface. The hybridization modifies the energy-momentum dispersions of the IPS on PbPc films as observed by angle-resolved two-photon photoemission. On the PbPc 1 monolayer film, the IPS band forms a band gap and back-folding appears at the first Brillouin zone boundary due to the periodic potential by the adsorbate lattice. The modification of the dispersion is accompanied by the intensity enhancement of the IPS. We attributed the origin of the modified dispersion and intensity enhancement to a hybridization of the IPS with a molecule-derived unoccupied level. From the photon energy-dependent measurement on multilayer films, we have found the diffuse unoccupied molecular level in the vicinity of the IPS. The tail part of the IPS wave function in the substrate is enhanced by the hybridization with the unoccupied state, and thus strengthens the transition from the occupied substrate band to the hybridized IPS.

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Section: Introductionmentioning

confidence: 99%

Hybridization of an unoccupied molecular orbital with an image potential state at a lead phthalocyanine/graphite interface

Yamada

Kawakita

Okui

et al. 2018

J. Phys.: Condens. Matter

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“…By subtracting two constant-current topographic STM images taken at two different sample biases (e.g., V 1 and V 2 ), the LDOS located between the V 1 and V 2 energy levels can be evaluated. Reproduced from ref (67). with permission from the PCCP Owner Societies.…”

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confidence: 99%

Unoccupied States Measurements, Spatial Mapping, and Nanoscale Structures of Organic Ultrathin Films

Yamada

2018

Mol. Sci.

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In this accounts, we summarize recent progress in experimental approaches to the investigation of the unoccupied electronic structures of organic ultrathin films, based on a combination of spectroscopic and microscopic techniques. On the occupied valence bands of the films, it has been extensively studied for a variety of organic molecules. However, systematic investigations of unoccupied electronic states still have been challenging because experimental techniques are limited. In this context, we have clarified the correlation between geometric and electronic structure using a combination of two-photon photoemission (2PPE) spectroscopy and scanning tunneling microscopy (STM). By using 2PPE, one can measure unoccupied states as well as occupied states in the vicinity of the Fermi level. Beyond the diffraction limit of light, STM can be a powerful means of mapping unoccupied electronic structures, not limited to the imaging of geometrical structures. Depending on the molecular density and substrate temperature, organic ultrathin films of polycyclic aromatic hydrocarbons on graphite substrates show a variety of structures, as demonstrated by microscopic observations on the nanoscale. It is apparent that the geometrical structures, especially molecular orientations as stressed throughout this accounts, have a strong impact on both occupied and unoccupied electronic structures. These findings, with a spectroscopic and microscopic understanding at the level of molecule, will provide fundamental insights into desirable electronic properties at organic/substrate interfaces.

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Image potential states of 2D materials

Borca,

Zandvliet

2024

Applied Materials Today

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Direct visualization of diffuse unoccupied molecular orbitals at a rubrene/graphite interface

Cited by 8 publications

References 47 publications

Hybridization of an unoccupied molecular orbital with an image potential state at a lead phthalocyanine/graphite interface

Hybridization of an unoccupied molecular orbital with an image potential state at a lead phthalocyanine/graphite interface

Unoccupied States Measurements, Spatial Mapping, and Nanoscale Structures of Organic Ultrathin Films

Image potential states of 2D materials

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