Hexaphenyl thin films on clean and carbon covered Au(111) studied with TDS and LEED

Müllegger, Stefan; Winkler, Adolf

doi:10.1016/j.susc.2006.01.018

Cited by 50 publications

(71 citation statements)

References 30 publications

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“…In the presence of the surfactant, 6P films of upright standing molecules are formed. Similar experiments have been performed with 6P [69] and 4P [96][97][98] films on gold surfaces. In both cases, a reorientation of the molecules has been observed.…”

Section: Tuning Molecular Orientation and The Role Of Defectssupporting

confidence: 59%

Nucleation and growth of thin films of rod-like conjugated molecules

Hlawacek

Teichert

2013

J. Phys.: Condens. Matter

107

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Abstract. Thin films formed from small molecules rapidly gain importance in different technological fields. To explain their growth, methods developed for zero-dimensional atoms as the film forming particles are applied. However, in organic thin film growth the dimensionality of the building blocks comes into play. Using the special case of the model molecule para-Sexiphenyl, we will emphasize the challenges that arise from the anisotropic and one-dimensional nature of building blocks. Differences or common features with other rodlike molecules will be discussed. The typical morphologies encountered for this group of molecules and the relevant growth modes will be investigated. Special attention is given to the transition between flat lying and upright orientation of the building blocks during nucleation. We will further discuss methods to control the molecular orientation and describe the involved diffusion processes qualitatively and quantitatively.

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Section: Tuning Molecular Orientation and The Role Of Defectssupporting

confidence: 59%

Nucleation and growth of thin films of rod-like conjugated molecules

Hlawacek

Teichert

2013

J. Phys.: Condens. Matter

107

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“…The 6P films grown on AuA C H T U N G T R E N N U N G (111) exhibit (21-3) oriented bulk crystals. [15] The corresponding molecular packing structure is almost identical to that shown in Figure 1 b for the 4PA C H T U N G T R E N N U N G (211) orientation, with tilt angles of a 1 = 08 for the flat-on and a 2 = 668 for the edge-on 6P molecules.…”

supporting

confidence: 54%

“…[2,3,13,14] The microscopic reason for the occurrence of the needles and the relation of the needle direction to the substrate morphology has not yet been unravelled; only in the case of Au as substrate has a recent study on polycrystalline Au surfaces provided some insight. [15,16] For this reason a more detailed investigation of the molecular conformation and, in particular, the magnitude of the interring twisting angle, in deposited 4P molecules is required, especially for those in direct contact with the substrate. Furthermore, to understand the growth of highly oriented thin films, Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy has been applied to reveal the molecular arrangement of ultrathin oligophenyl films [p-quaterphenyl (4P) and p-hexaphenyl (6P)] on AuA C H T U N G T R E N N U N G (111).…”

Section: Introductionmentioning

confidence: 99%

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Organic Molecular Beam Deposition of Oligophenyls on Au(111): A Study by X‐ray Absorption Spectroscopy

et al. 2006

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Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy has been applied to reveal the molecular arrangement of ultrathin oligophenyl films [p-quaterphenyl (4P) and p-hexaphenyl (6P)] on Au(111). In the half-monolayer films the molecules lie flat on the surface but still have a considerable inter-ring twist of 30 degrees -40 degrees , similar to the gas-phase conformation. In the saturated monolayer film the second half of the molecules is side-tilted by an angle of less than 66 degrees with respect to the surface. This arrangement is already similar to that in bulk net planes of thicker films parallel to the surface, that is, the 4P(211) and 6P(21-3) planes, respectively.

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“…Sublimation processes are advantageous compared to precipitation from solution, because the organic molecules deposited from the gas phase in high vacuum with a superior purity suitable for high performance application. In the past p6P has been grown on various solid supports such as dielectric [56][57][58][59] and metallic [60][61][62] surfaces, but muscovite mica emerged as the most favourable growth substrate [39,63]. The deposition of p6P on a freshly cleaved muscovite mica substrate at elevated substrate temperatures leads to the formation of parallely aligned so called nanofibers, whereas fiberlike aggregates but without parallel alignment are observed on alkali halides [57], titan dioxide [58] and even on phlogophite [10,63].…”

Section: Fig 12mentioning

confidence: 99%

Organic Molecular Nanotechnology

Schiek

Balzer

Al‐Shamery

et al. 2008

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Zur Homepage der Dissertation AbstractFormation of needle-like crystals from inorganic as well as from organic semiconductors such as para-phenylenes, α-thiophenes and phenyl-thiophene co-oligomers on dielectric surfaces has attracted increasing interest within the last years. The para-hexaphenylene has proven to be a versatile building block for generating long, parallely aligned organic nanofibers by a self-assembly process on a muscovite mica substrate via sublimation in high vacuum. These nanofibers possess outstanding optical properties like strong, polarised blue fluorescence in high quantum yields after unpolarised excitation with UV light, waveguiding and lasing features. Furthermore, they are chemically and thermically stable and can be easily detached from the growth substrate to serve as key elements in next generation optoelectronic and nanophotonic devices. Owing to their typical height and width on a nanometer scale and length up to one millimeter, the fibers bridge the gap between microscopic and macroscopic dimensions. The morphology of the nanofibers (length, height, width, aspect ratio, bending into rings) is susceptable to process parameters and pretreatment of the substrate. But chemically functionalisation of the molecular building block as key step of this thesis widens the scope of possibilities: Nanoaggregates with tailored morphology and optical properties are generated from designed functionalised molecular building blocks. Functional groups have been implemented at the 1,4´´´-para-positions of p-quaterphenylenes using a non-trivial Suzuki cross-coupling strategy. Symmetrically as well as non-symmetrically functionalised oligomers have been achieved in excellent yields and high purity. Additionally, the synthesis of phenyl-thiophene cooligomers and their acceptability for the nanofiber growth on muscovite mica via organic molecule deposition in high vacuum are presented. The fluorescence peak emission frequency of the nanostructures from the substituted p-quaterphenylenes shifts within the blue depending on the functionalisation. While dimensions are still influenced by the growth parameters, the overall shape (i.e. cross-section) of the aggregates alters significantly with the functional group. Even new properties like nonlinear optical activity are accessible. Due to intrinsic nonzero hyperpolarisability of push-pull functionalised oligomers, the respective nanofibers act as frequency doublers and emit strong second harmonic light after excitation with near infrared femtosecond laser pulses. Note that this design approach is possible while conserving the concept of highly crystalline nanofibers. Thus, a new route of bottom-up nanotechnology is presented starting from organic molecular synthesis towards generating of tailormade organic nanofibers opening new prospects for future nanotechnology. 3 ZusammenfassungDie Bildung von nadelförmigen Kristallen aus anorganischen und organischen Halbleitermolekülen wie zum Beispiel para-Phenylenen, α-Thiophenen und Phenylthiophen Co-oligomeren fa...

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Hexaphenyl thin films on clean and carbon covered Au(111) studied with TDS and LEED

Cited by 50 publications

References 30 publications

Nucleation and growth of thin films of rod-like conjugated molecules

Nucleation and growth of thin films of rod-like conjugated molecules

Organic Molecular Beam Deposition of Oligophenyls on Au(111): A Study by X‐ray Absorption Spectroscopy

Organic Molecular Nanotechnology

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