2019 |
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5. | X. Yang, L. Egger, J. Fuchsberger, M. Unzog, D. Lüftner, F. Hajek, P. Hurdax, M. Jugovac, G. Zamborlini, V. Feyer, G. Koller, P. Puschnig, F. S. Tautz, M. G. Ramsey, S. Soubatch Coexisting Charge States in a Unary Organic Monolayer Film on a Metal Journal Article In: J. Phys. Chem. Lett., vol. 10, pp. 6438-6445, 2019. Abstract | Links | BibTeX | Tags: DACH @article{Yang2019a, The electronic and geometric structures of tetracene films on Ag(110) and Cu(110) have been studied with photoemission tomography and compared to that of pentacene. Despite similar energy level alignment of the two oligoacenes on these surfaces revealed by conventional ultraviolet photoelectron spectroscopy, the momentum-space resolved photoemission tomography reveals a significant difference in both structural and electronic properties of tetracene and pentacene films. Particularly, the saturated monolayer of tetracene on Ag(110) is found to consist of two molecular species that, despite having the same orientation, are electronically very different—while one molecule remains neutral, another is charged because of electron donation from the substrate. |
4. | X. Yang, L. Egger, P. Hurdax, H. Kaser, D. Lüftner, F. C. Bocquet, G. Koller, A. Gottwald, P. Tegeder, M. Richter, M. G. Ramsey, P. Puschnig, S. Soubatch, F. S. Tautz Identifying surface reaction intermediates with photoemission tomography Journal Article In: Nat. Commun., vol. 10, pp. 3189, 2019. Abstract | Links | BibTeX | Tags: DACH @article{Yang2019, The determination of reaction pathways and the identification of reaction intermediates are key issues in chemistry. Surface reactions are particularly challenging, since many methods of analytical chemistry are inapplicable at surfaces. Recently, atomic force microscopy has been employed to identify surface reaction intermediates. While providing an excellent insight into the molecular backbone structure, atomic force microscopy is less conclusive about the molecular periphery, where adsorbates tend to react with the substrate. Here we show that photoemission tomography is extremely sensitive to the character of the frontier orbitals. Specifically, hydrogen abstraction at the molecular periphery is easily detected, and the precise nature of the reaction intermediates can be determined. This is illustrated with the thermally induced reaction of dibromo-bianthracene to graphene which is shown to proceed via a fully hydrogenated bisanthene intermediate. We anticipate that photoemission tomography will become a powerful companion to other techniques in the study of surface reaction pathways. |
3. | L. Egger, B. Kollmann, P. Hurdax, D. Lüftner, X. Yang, S. Weiß, A. Gottwald, M. Richter, G. Koller, S. Soubatch, F. S. Tautz, P. Puschnig, M. G. Ramsey Can photoemission tomography be useful for small, strongly-interacting adsorbate systems? Journal Article In: New J. Phys., vol. 21, pp. 043003, 2019. Abstract | Links | BibTeX | Tags: DACH @article{Egger2018, Molecular orbital tomography, also termed photoemission tomography, which considers the final state as a simple plane wave, has been very successful in describing the photoemisson distribution of large adsorbates on noble metal surfaces. Here, following a suggestion by Bradshaw and Woodruff (2015 New J. Phys. 17 013033), we consider a small and strongly-interacting system, benzene adsorbed on palladium (110), to consider the extent of the problems that can arise with the final state simplification. Our angle-resolved photoemission experiments, supported by density functional theory calculations, substantiate and refine the previously determined adsorption geometry and reveal an energetic splitting of the frontier π-orbital due to a symmetry breaking which has remained unnoticed before. We find that, despite the small size of benzene and the comparably strong interaction with palladium, the overall appearance of the photoemission angular distributions can basically be understood within a plane wave final state approximation and yields a deeper understanding of the electronic structure of the interface. There are, however, noticeable deviations between measured and simulated angular patterns which we ascribe to molecule-substrate interactions and effects beyond a plane-wave final state description. |
2018 |
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2. | X. Yang, I. Krieger, D. Lüftner, S. Weiß, T. Heepenstrick, M. Hollerer, P. Hurdax, G. Koller, M. Sokolowski, P. Puschnig, M. G. Ramsey, F. S. Tautz, S. Soubatch On the decoupling of molecules at metal surfaces Journal Article In: Chem. Commun., vol. 54, pp. 9039-9042, 2018. Abstract | Links | BibTeX | Tags: DACH @article{Yang2018, We report a method to achieve physical and electronic decoupling of organic molecules from a metal surface. Oxygen adsorbed on the Cu(100) surface immobilizes the surface electrons in the Cu–O covalent bonds. This results in electronic surface hardening and prevents charge transfer from the metal into perylene-tetracarboxylic dianhydride molecules subsequently deposited on this surface. |
2017 |
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1. | P. Hurdax Charge transfer to organic molecules promoted by ultrathin insulating layers on metals Masters Thesis 2017. @mastersthesis{Hurdax2017, |
2019 |
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5. | Coexisting Charge States in a Unary Organic Monolayer Film on a Metal Journal Article In: J. Phys. Chem. Lett., vol. 10, pp. 6438-6445, 2019. |
4. | Identifying surface reaction intermediates with photoemission tomography Journal Article In: Nat. Commun., vol. 10, pp. 3189, 2019. |
3. | Can photoemission tomography be useful for small, strongly-interacting adsorbate systems? Journal Article In: New J. Phys., vol. 21, pp. 043003, 2019. |
2018 |
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2. | On the decoupling of molecules at metal surfaces Journal Article In: Chem. Commun., vol. 54, pp. 9039-9042, 2018. |
2017 |
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1. | Charge transfer to organic molecules promoted by ultrathin insulating layers on metals Masters Thesis 2017. |