Vertical bonding distances of PTCDA on Au(111) and Ag(111): Relation to the bonding type
2007; Elsevier BV; Volume: 601; Issue: 6 Linguagem: Inglês
10.1016/j.susc.2007.01.020
ISSN1879-2758
AutoresS.K.M. Henze, Oliver Bauer, T.-L. Lee, M. Sokołowski, F. Stefan Tautz,
Tópico(s)Organic Electronics and Photovoltaics
ResumoThe vertical bonding distance of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) above the Au(1 1 1) surface has been measured by the normal incidence X-ray standing wave (NIXSW) technique. The carbon skeleton of PTCDA has a vertical distance of D = (3.27 ± 0.02) Å to the Au(1 1 1) substrate. This distance corresponds very nearly to the sum of the van der Waals radii of carbon and gold, suggesting the adsorption to be a physisorptive one. In contrast, the PTCDA/Ag(1 1 1) interface which according to spectroscopic data follows the standard model of chemisorption very closely, shows a considerably smaller bonding distance of D = (2.86 ± 0.01) Å [A. Hauschild, K. Karki, B.C.C. Cowie, M. Rohlfing, F.S. Tautz, M. Sokolowski, Phys. Rev. Lett. 94 (2005) 036106, comment: Rurali et al., Phys. Lett. 95 (2005) 209205, reply: Phys. Rev. Lett. 95 (2005) 209206]. The different vertical adsorption heights of PTCDA on gold and silver are discussed in relation to the different bonding mechanisms on both noble metal surfaces.
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