Coverage-dependent adsorption geometry of octithiophene on Au(111)

Varene, Erwan; Bogner, Lea; Meyer, Stephan; Pennec, Yan; Tegeder, Petra

doi:10.1039/c1cp22875g

Cited by 13 publications

(13 citation statements)

References 45 publications

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“…This localized electric field is the main cause of the work function shift. In experiments, the magnitude of this localized field can possibly be estimated using atomic force microscopy techniques as reported in recent studies. , However, we find that the resulting work function changes deviate significantly from the expected work function changes predicted by the conventional Helmoltz equation, Δ W = μ z e /ϵ A , where A is the area of the graphene supercell. − Notably, in the case of guanine with a large dipole moment (−2.38 D), we have obtained a small work function increase (0.15 eV), which is in apparent contradiction with the Helmholtz equation. This provides clear evidence of the limited validity of simple electrostatic approximations for weakly adsorbed systems, such as DNA/RNA nucleobases on graphene, and highlights the importance of full quantum mechanical treatment of the problem.…”

contrasting

confidence: 47%

Molecular Dipole-Driven Electronic Structure Modifications of DNA/RNA Nucleobases on Graphene

Yin

Červenka

Medhekar

2017

J. Phys. Chem. Lett.

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The emergence of graphene in recent years provides exciting avenues for achieving fast, reliable DNA/RNA sensing and sequencing. Here we explore the possibility of enhancing electronic fingerprints of nucleobases adsorbed on graphene by tuning the surface coverage and modifying molecular dipoles using first-principles calculations. We demonstrate that intermolecular interactions have a strong influence on the adsorption geometry and the electronic structure of the nucleobases, resulting in tilted configurations and a considerable modification of their electronic fingerprints in graphene. Our analysis reveals that the molecular dipole of the nucleobase molecules plays a dominant role in the electronic structure of graphene-nucleobase systems, inducing significant changes in the work functions and energy level alignments at the interface. These results highlight tunable control of the measured molecular signals in graphene by optimizing the surface contact between nucleobases and graphene. Our findings have important implications for identification and understanding of molecular fingerprints of DNA/RNA nucleobases in graphene-based sensing and sequencing methods.

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contrasting

confidence: 47%

Molecular Dipole-Driven Electronic Structure Modifications of DNA/RNA Nucleobases on Graphene

Yin

Červenka

Medhekar

2017

J. Phys. Chem. Lett.

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“…A Ti:Sapphire oscillator provided femtosecond laser pulses which were amplified in a regenerative amplifier and subsequently converted into the visible spectrum using an optical parametric amplifier and frequency-doubled into the UV regime using a BBO crystal. The laser setup is described in detail elsewhere [15,17,33,34]. In the illumination experiments, the photon flux and energy fluence varied from measurement to measurement but were always on the order of 2 (energy fluence), respectively.…”

Section: Experimental Methodsmentioning

confidence: 99%

Photo-induced and thermal reactions in thin films of an azobenzene derivative on Bi(111)

Bronner

Tegeder

2014

New J. Phys.

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Azobenzene is a prototypical molecular switch which can be interconverted with UV and visible light between a trans and a cis isomer in solution. While the ability to control their conformation with light is lost for many molecular photoswitches in the adsorbed state, there are some examples for successful photoisomerization in direct contact with a surface. However, there the process is often driven by a different mechanism than in solution. For instance, photoisomerization of a cyano-substituted azobenzene directly adsorbed on Bi(111) occurs via electronic excitations in the substrate and subsequent charge transfer.In the present study we observe two substrate-mediated trans-cis photoisomerization reactions of the same azobenzene derivative in two different environments within a multilayer thin film on Bi(111). Both processes are associated with photoisomerization and one is around two orders of magnitude more efficient than the other. Furthermore, the cis isomers perform a thermally induced reaction which may be ascribed to a back-isomerization in the electronic ground state or to a phenyl ring rotation of the cis isomer.Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. New J. Phys. 16 (2014) 053004 C Bronner and P Tegeder New J. Phys. 16 (2014) 053004 C Bronner and P Tegeder 3 New J. Phys. 16 (2014) 053004 C Bronner and P Tegeder 4 New J. Phys. 16 (2014) 053004 C Bronner and P Tegeder 5 New J. Phys. 16 (2014) 053004 C Bronner and P Tegeder 7

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“…A detailed knowledge about the electronic structure of the molecules in contact with metal substrates is a key issue in order to elucidate the excitation mechanism for the photostimulated isomerization. 2PPE has been used in various adsorbate-substrate systems to study adsorbate and image potential states [76,77,78,79,80,81,82,83]. Moreover, 2PPE can be carried out in a time-resolved fashion for the determination of electron dynamics on a femtosecond time scale [77,84].…”

Section: The Present Reviewmentioning

confidence: 99%

Optically and thermally induced molecular switching processes at metal surfaces

Tegeder

2012

J. Phys.: Condens. Matter

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123

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Using light to control the switching of functional properties of surface-bound species is an attractive strategy for the development of new technologies with possible applications in molecular electronics and functional surfaces and interfaces. Molecular switches are promising systems for such a route, since they possess the ability to undergo reversible changes between different molecular states and accordingly molecular properties by excitation with light or other external stimuli. In this review, recent experiments on photo- and thermally induced molecular switching processes at noble metal surfaces utilizing two-photon photoemission and surface vibrational spectroscopies are reported. The investigated molecular switches can either undergo a trans-cis isomerization or a ring opening-closure reaction. Two approaches concerning the connection of the switches to the surface are applied: physisorbed switches, i.e. molecules in direct contact with the substrate, and surface-decoupled switches incorporated in self-assembled monolayers. Elementary processes in molecular switches at surfaces, such as excitation mechanisms in photoisomerization and kinetic parameters for thermally driven reactions, which are essential for a microscopic understanding of molecular switching at surfaces, are presented. This in turn is needed for designing an appropriate adsorbate-substrate system with the desired switchable functionality controlled by external stimuli.

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Coverage-dependent adsorption geometry of octithiophene on Au(111)

Cited by 13 publications

References 45 publications

Molecular Dipole-Driven Electronic Structure Modifications of DNA/RNA Nucleobases on Graphene

Molecular Dipole-Driven Electronic Structure Modifications of DNA/RNA Nucleobases on Graphene

Photo-induced and thermal reactions in thin films of an azobenzene derivative on Bi(111)

Optically and thermally induced molecular switching processes at metal surfaces

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