Polyaromatic Hydrocarbons on Coinage Metal Surfaces

Richardson, Neville V.

doi:10.1002/9783527680580.ch41

Cited by 3 publications

(3 citation statements)

References 107 publications

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“…The size of the schematic of van der Waals isosurface of flat-lying molecule is larger than the pair of two protrusions. The molecular footprint of perylene is calculated to be 107 Å 2 (9.17 Å × 11.68 Å) in ref and 95 Å 2 (8.6 Å × 11.1 Å) in ref . In either case, it is impossible to accommodate two flat-lying perylene molecules into the rectangular unit cell (194 Å 2 ).…”

Section: Resultsmentioning

confidence: 95%

“…The geometric and electronic properties of perylene ultrathin films on well-defined surfaces have been investigated intensively in the past. − Most of the previous studies have used metal substrates, where the substrate–molecule interaction dominates over the intermolecular interaction. Therefore, adsorption geometry with the molecular plane parallel to the surface has been frequently reported in the first contact layer.…”

Section: Introductionmentioning

confidence: 99%

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Structural Characterization and Photoluminescence Properties of Monolayer Perylene on a Graphite Surface

et al. 2020

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The correlation between geometric structures and photoluminescence properties of the monolayer perylene (C 20 H 12 ) on a graphite surface was investigated by using a combination of scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and photoluminescence spectroscopy. The formation of a well-ordered perylene monolayer (ML) was confirmed upon deposition of perylene onto the room temperature substrate followed by cooling to liquid nitrogen temperature. A rectangular unit cell with a point-on-line coincidence was identified by a quantitative analysis of the LEED patterns; it was the only structure found for coverages up to 1 ML. The observed STM images clarified the molecular pair (dimer) arrangement with standing molecular configuration. The dimer arrangement was further corroborated by photoluminescence measurements, which was characterized as orange light emission (centered at a wavelength of 610 nm) from the excited state of the perylene dimer (excimer). In contrast, the perylene dimer structure was not found on the room temperature substrate. The absence of dimers is consistent with the green-yellowish photoluminescence reported for the monomeric form of the perylene crystal. The combination of STM, LEED, and photoluminescence spectroscopy allows the linking of a film structure with its photoluminescence properties. The present results demonstrate that the optoelectronic properties of organic materials can be controlled even at the monolayer limit.

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Section: Resultsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Structural Characterization and Photoluminescence Properties of Monolayer Perylene on a Graphite Surface

et al. 2020

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“…The adsorption of PAHs has been extensively studied on many surfaces [19]. Most of this past work has focused on the interaction of the PAH molecules with the substrate.…”

Section: Introductionmentioning

confidence: 99%

Revealing the molecular structure of soot precursors

Wang

Bartelt

Ragan

et al. 2018

Carbon

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The earliest stages of soot formation in flames are believed to involve the formation of small, nanoscale clusters of polycyclic aromatic hydrocarbon molecules. The structure of these clusters is still highly uncertain, however, impeding the construction of quantitative models of soot inception and growth. To provide insight into the structure of incipient soot, we produced nanoclusters of hydrocarbon molecules by annealing coronene films deposited on Pt(111), and examined them with scanning tunneling microcopy. We find that clusters containing~20e100 molecules, are disordered agglomerations of stacks that are~5e6 molecules tall. These structures are quite distinct from crystalline coronene, but bear a striking resemblance to recently proposed models for the equilibrium structure of similarly-sized clusters that are assumed to initiate soot formation. In contrast to mature soot, the surfaces of these clusters contain very few molecules with graphitic planes oriented parallel to the surface.

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Formation and regulation of unoccupied hybridized band with image potential states at perylene/graphite interface

Yamada

Ito

Kawakita

et al. 2019

The Journal of Chemical Physics

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Occupied and unoccupied electronic structures of submonolayer perylene (C20H12) on a graphite surface have been investigated using two-photon photoemission (2PPE) spectroscopy for two phases at room and low temperatures. Low energy electron diffraction measurements indicated that the molecules are disordered at room temperature and form a well-ordered superstructure below 180 K. In 2PPE, a specific unoccupied peak (Lx) was observed at around room temperature (>180 K) but not at low temperature (<180 K). The temperature-dependence of the excitation probability was attributed to a contribution of a diffuse unoccupied state, which is characterized by the molecular orbital extending outside the perylene molecular framework. At around room temperature, perylene adopts a flat-lying molecular orientation so that the diffuse state can hybridize with a free-electron-like unoccupied surface state, image potential states (IPS). As a result, the hybridized Lx state can be excited from the occupied bulk band through the IPS-mediated process. In contrast, hybridization is not efficient in the low-temperature phase due to the standing molecular orientation, which decouples the molecule away from the image plane of the substrate. The size of molecular islands also affects hybridization between the diffuse states and IPS because the two states encounter each other at the edge part of molecular aggregates. The temperature-dependent 2PPE results indicate that the molecular orientation and island size of perylene are directly linked to the formation of hybridized states, and thus, the excitation probability at the interface can be regulated by the morphology on the surface.

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Polyaromatic Hydrocarbons on Coinage Metal Surfaces

Cited by 3 publications

References 107 publications

Structural Characterization and Photoluminescence Properties of Monolayer Perylene on a Graphite Surface

Structural Characterization and Photoluminescence Properties of Monolayer Perylene on a Graphite Surface

Revealing the molecular structure of soot precursors

Formation and regulation of unoccupied hybridized band with image potential states at perylene/graphite interface

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